Microbial Interactions: Symbiosis, Mutualism & Parasitism | BIOL 8470 Ch 27

[00:00:00][Music] welcome back we are starting the chapter 27 and we will talk about the microbial interaction in this chapter so the first we are looking at the many types of microbial interactions and we are going to see compare contrast these different types of interactions so the first thing that what we are going to talk about is the symbiosis and this is an association of two or more different species of organisms now many times we are going to see that these could be beneficial for both one may be affected the other may be not affected sometimes one will cause harm to the other one and all sorts of relationship not only there are two that many times we will see that there are more than two even four or five different components or organisms are involved in this process so here are just couple of terms that we are going to discuss is ectosymbiont are the organism located on the surface of another usually a larger organism and this you can just think about that some bacteria that are living on our skin like a staphylococcus aureus or staphylococcus epidermidis these are very common there are several different types that live on our skin we can think about that these are our ectosymbion on the other hand the end endosymbiont is the organism located within another organism and mainly the important thing that i want you to understand here most of the time the endosymbionts are within the cell of another organism that's the important word within the cell it is just not inside the animal inside one of the cells that is the most important part so what is the relationship of the symbiont symbian is any organism that has a specific relationship with another that can be characterized as a mutualism cooperation commensalism but there are other emensalism predation also parasitism and etc so here we are looking at some of these different types of relationship and we are starting with mutualism so mutualism is a type of symbiosis in which the both partners actually gain from the association and they are metabolically dependent on each other so this relationship is obligatory both of them a needs b b needs a and both of them benefit from each other this is mutualism the second one is the cooperation where you have the a is positive but not obligatory interaction between the two organism and just the difference is that a is benefited from b b is benefited from a just similar to mutualism but the difference is that mutualism is an obligatory relationship you have to have that for the existence of both the different organisms they will be benefited in the with the help of the other but this is not obligatory the next one is the commensalism where the a helps b and b is benefited but b does not do any positive or negative impact on a so this relationship is just one-way traffic the other the b the second organism doesn't do any harm nor it benefits the a organism on the other hand the emensalism is a relationship which the product of one organism has a negative effect on the other organism the organism itself doesn't really harm directly the b it is a scenario where the product of the a will harm the b organism then we have other type of relationship like a predation this is a relationship which one organism captures and feeds on the other this is very straightforward then we have parasitism parasitism is a type of relationship where one organism captures and feeds on the another one and in this relationship the one of the host is which is the host which hosts the parasite is always harmed so this is always a harmful relationship with the host and the parasite is always benefited then we have this competition and this competition is an interaction between the two organisms attempting to use the same resource which is nutrient or space and one may out-compete the other or both of them can reduce their amount or amount of population while sharing that resource so it could be both uh there in one relationship it can out compete the other ones so the other has to find some other food source for an example on the other hand the same food source is being shared between the a organism and the b organism but both of them will grow in a reduced number so these are the main different kinds of symbiosis that we are going to examine in this chapter so first take a look at the mutualism we're going to talk about these first so here we are looking at the mutualism where some reciprocal benefit of both the partners and this relationship with some degree of obligation it's a mutualistic and the hosts are dependent on each other and often the partners cannot live separately that means that they are obligatory so what are the different types of mutualism there are many many examples of that and even we are not talking about even the human and microbial relationship it is very very complex let's take up some of the examples that we have studied in the laboratory and very well characterized so sometimes this endosymbiotic microbes provide the needed vitamin and the amino acid in general to many of these insects so we are talking about these two different insects and we're going to give these examples so one is the acid and this a book narrow effeticola interaction we will come back to that in the next slide but here we want to talk about this interesting relationship which is an insect and ulbacia relationship so the ulbacia full name is woolbakia pipentis it's a recapsule bacteria so what is a rickettsia a rickettsia is a very interesting group of bacteria they're almost like viruses and they cannot live by themselves freely like other bacteria what it means that they need a living cell or tissue to live in or living cell in a tissue just not tissue space living cell to live so they come they're completely obligatory and are endosymbined as they live inside the cell so they infect a large variety this particular wolbachia species infect a large a variety more than two million insect species they live in the cytoplasm of infected females and very interestingly they can modify fertilization event in the host this is widely studied in a particular wasp called nesonia vitripenas this is a particular wasp that is infected with this ulbacchia if an infected male sperm try to fertilize an egg of an uninfected female wolbachia modifies the chromosome distribution as if the eggs were never fertilized so they will fail to grow but on the other hand if an infected male sperm fertilizes an infected egg both of them male female both are infected with ulbachia the development is normal with normal sex distribution so in other insects ulbacchia simply kill all the male offsprings and the females develop just by cloning themselves a process you know very well we call this as a parthenogenesis so this limits the genetic diversity but this ensures that ulbacchia transmission is 100 percent among these and this is a great success for this ulbacia now another interesting thing is that that scientist now trying to see that the wolbachia actually also stop the virus from being spread by the viral vectors and once that study has been done now the scientists are trying to do something with the eddis egyptian mosquito these egyptian mosquito you know that it's a very well biological vector for say zika dengue west nile chikungunya virus many of these viruses are spread by this mosquito it is egyptian so the scientists are trying to infect these 80s egyptian mosquito in the laboratory artificially because the egyptian is not infected by ulbaqia normally so it's a trans infection it's an artificial infection and the scientists have observed that in fact it is true that if the these mosquitoes are infected with the ulbacia they will not be able to transmit the viruses so ulbacia blocks the viral transmission so the scientists are working on this that maybe at some point of time that they will be releasing these infected adhd mosquito with the ulbachia and they can naturally mate with the wild types and then can reduce the amount of this mosquito which will be capable of carrying these viruses so this is basically a biological vector control that can be done with the ulbachia so let's talk about the next interaction so here what we are looking at that the mutualistic association is very common between the microbes of the insect partly because the insect often consumes the plant sap or animal fluids lacking essential vitamins and amino acids and these are provided by the bacteria symbians in exchange for a safe habitat so the first one we are looking at is a mature aphid a mature acid contains these boku nera effeticola bacteria within the specialized cell called bacteriocytes the genome of these bacteria are very very small very interestingly and we'll come back to that but let us discuss that what exactly what they do so these aphids feed on the plant sap unfortunately the plant saps do not contain any of the nitrogenous material that's the reason that they need a nitrogenous compound to synthesize their proteins so these uh book nero effeticola produ fix the nitrogen and produce the nitrogenous compound to these on the other hand the be a fide cola is a safe haven for the food as well as shelter in these aphids and it is interesting that the genome of these bacteria they are very small about 0.65 megabase and this acid and the buchner effeticolar relationship can be traced back to almost like 150 million years so these aphids and these book neurofedicola co-evolved over the period of time and what has been shown that why their genome is so small because they offer the very extreme genetic stability where there is no duplication of the genome no translocation inversion or horizontal transfer so why this is it is because as this relationship is extremely stable this buccaneer effeticola never tried to venture outside these aphids to look for anything if they have tried to look for some other habitats then there is need for some more genes which are needed for the survival of that bacteria as these bacteria never try to venture out to find something else they need very little amount of gene for their survival because their environment never changed over the period of time a classic example of a co-evolution on the other hand there is also a classic relationship in between a protozoa termite as well as many different type of bacterial termite relationship so the termite provides a food for the protozoan protozoan digests the cellulose and wood particles provide nutrients to the termite and in this process there are several different types of microbes involved so the main thing that is important is that the termite feed on the wood which contains the cellulose and the hemi cellulose and these are like 15 20 000 glucose chains and it is extremely difficult for the termite to break them down hermite do themselves produce the cellulose enzyme to digest the cellulose but that is not enough to break down these cellulose so what they do that they do have this digestion problem and that's enough this is one another thing is that from the wood source they do not get sufficient amount of nitrogen that is required there for their protein synthesis or the nucleic acid synthesis so for this they have a very complex symbiotic system in termites so what you are seeing that right here this is a picture of the trichonymphus species this is a multi-flagellated protozoan and this protozoa here in purple lives in the termite gut and along with that there are several different type of bacteria which are also outside the trichonympha in the termite gut and there is also a type of microbe inside which is known as elusive microbial that live inside that protozoa so within the termite gut the bacteria convert the nitrogen to the ammonia which is taken up and converted to glutamine by the trichome species along with that they also digest the cellulose the protist relies on this elusive microbial to convert this glutamine to other amino acids which are released with other cofactors that the protists cannot synthesize both the protists and the trichonympha and elusi microbian species also ferment glucose to acetate hydrogen and carbon dioxide these products are exported by the protist and made available to the termite which also relies on a free swimming gut bacteria to boost the acetate level through the reductive acetyl-coa pathway and these are called the acetogens in addition the termite also harbors this methanogenic bacteria that will take up this carbon dioxide that is being produced and the hydrogen and convert them to methane which will be excreted out and it does not even stop there there is also another bacteria which are spirochetes they also live on the outside of this triconium for protozoa what they do that these have the motility and this motility keeps this trichonimpha inside the gut because remember that that the gut is motile so the digestive material is constantly being expelled through the gut that gut motility may expel these tricho nympha but these spirochetes these are the undulating movement screw-like movement that will keep the trichonim inside the gut without being expelled these are also very interesting that how many different bacteria as well as a protozoa and the termite are in a symbiotic relationship so the next example that we are looking at mutualistic relationship is the zooxanthellae these are the marine invertebrates they harbor these are zooxanthellae and these are dinoflagellate and these they provide this organic carbon to the host and essentially this there's a species called symbiodinium this is a dinoflagellate which provide almost 95 percent of the carbon they fix because these are pigmented and the coral has a pigment that protects the algae from the uv radiation and also the coral provide that nitrogenous compound phosphates and carbon dioxide to these endosymbionts because they feed on other heightened animals as such nitrogenous material provided to the zooxanthellae by these corals on the other hand what happens is a very interesting thing coral bleaching is the loss of either the photosynthetic pigments from the zooxanthellae or complete expulsion of these dinoflagellates which are the zooxanthellae so why this happens this is caused by the temperature increase and even a two degree celsius rise in the sea temperature can cause the corals to bleach out and this has been seen in many parts of the work and this is a concern coral bleaching will pose a danger to these ecosystems so let's take a look at uh these that how this works so here what we are looking at that this is a typical rose coral and this is green in color due to the abundant zooxanthin within the tissue and the corals provide this extensive habitat for a bacterial growth as well as the zooxanthellae growth and here what we are seeing that this is the bleaching of the coral see that this part is bleached out and that's what we are seeing so let's take a look at the cross section of a coral and what they have so outside they do have a layer which is a mucous layer and this mucous layer contains different types of bacteria one type of population the bacteria in this mucous layer fix the nitrogen because they also do this chitin degradation so right here with the mouth living part of the coral this is called the gastrodermal cavity and these corals along with the water get their food and this could be many different types of tiny small crustaceans and they do have an exoskeleton which is made up of chitin and these bacteria can digest that chitin and provide the nitrogen and here you can see that the zooxanthellae is lining the gastrodermal cavity so as they are inside the gastrodermal cavity the advantage is that they are protected from the ultraviolet and if using the nitrogen as well as carbon dioxide which is provided by the coral they thrive and fix the carbon dioxide into the sugars which is utilized by the coral then there is another a second group of bacteria which lives in the gastrodermal cavity as well shown as these dots and the exact function for them is not very well known there is also another group which lives below this calicoblastic layer and what is a calicoblastic epithelial cells these are the epithelial cells which secrete and builds the exoskeleton or the tough exoskeleton of the coral that we are familiar with inside this exoskeleton or the coral skeleton there are another third group of bacteria live in there it is thought that these are actually very important for the nutrient recycling so you can see that three different bacterial population as well as zooxanthellae all live in harmony in a symbiotic relationship which is a mutualism another type of mutualism is a sulfide based mutualism and we are going to look at a tube warm example which along with the bacteria which exists thousands of meters below the ocean surface so we are going to see that these tube worms do have a relationship with this chemolithotropic bacterial endosymbionts which lives inside the cells of these tube worms and they are within a specialized organ called trophosome so these bacteria live within their trophosome and they help carbon dioxide fixation with the electrons provided by the hydrogen sulfide so we are going to take a look at that before that what we are looking at that in this figure summarizes the chemical reaction between the seawater and the rocks that occur varied range of temperature on the seafloor the carbon and energy that support a diverse collection of microbial communities in specific niches within the vent system so these are the hydrothermal vents through which these hot gases do pass out into the ocean floor very deep ocean floor the water don't boil at that temperature because of the pressure the temperature could be very high so let's take a look at what are these different niches the first thing that what we are looking at is a very cold seawater say from here these are away from the vent cold sea water two degrees celsius at that time so they do contain oxygen sulfates and the carbon dioxide and these seeps through the seafloor crack and this is one of the community lives in there then there is another zone right here which is shown as the mesophilic zone and this is moderate temperature about 15 degrees celsius to about 45 degrees celsius this is high to about low oxygen and microbes obtain energy by aerobic chemical reaction using hydrogen sulfide methane and hydrogen in the fluids or metal sulphides in the rocks these are some of the examples then we are going into a zone which we call as a thermophilic zone high temperature about 50 to 75 degrees celsius in the thermophilic zone and low to almost no oxygen and the thermophilic microbes obtain their energy from anaerobic chemical reactions using hydrogen sulfates iron organic carbon these are some of them some of the nutrients that is available to them then what we have is a hyper thermophilic zone very high temperature which is 80 degree to 125 degrees celsius and in the hyper thermophilic zone this brown area there is no oxygen but there is still life in there hyperthermophilic microbes obtain energy from the end products of high temperature chemical reactions and below that which is the life does not exist and the temperature here is about 130 to 140 degrees celsius and hydrogen methane carbon dioxide and perhaps organic carbon created by the geothermal process by the microbes percolate upward via the cracks of the ocean crust from this area so this is basically an overall biogeochemical cycle and the vent and related geological activity what happens in different tiers which is basically the cold and then mesophilic zone then thermophilic and hyperthermophilic zone in the vent system now we are going to look at an example of this so here you are seeing a community of tube worms which is the riftia species so these are found in a galapagos rift and they are in a depth of almost 2 500 meters depth and they are near some hydrothermal vents so here is a schematic of the worm which could be a meter long three feet long more than three feet long so they have these large gill plumes which could be about 20 centimeter and then they do have this particular area which is known as this vestimentum the vestimentum contains the brain and it contains the animal's heart and the top end is the respiratory gill plume and inside the trunk the worm is a trophosome and this trophosome consists of a primarily these endosymbiotic bacteria inside the associated cells and the blood vessels so the posterior end is known as the opisthosome which anchors these tube worms through the substrate so on the other hand here we are looking at that what are the different types of reactions that is going on in these two worms so what we are looking at that just from the surrounding sea water using the gill plumes you have oxygen carbon dioxide and hydrogen sulfide is taken in to this area and the hydrogen sulfide can combine with the hemoglobin of this worm and as well as carbon dioxide and oxygen can also combine to some extent and this is provided to the bacteria in the trophosome so once the bacteria gets this sulfide with the help of an oxygen it produces the sulfur oxidation produce this atp and nadph these are the energy molecules by the help of the atp nadph these bacteria fix carbon dioxide with the kelvin benson cycle so these reduced carbon compounds which are utilized by this worm and this is their main carbon source so these products are little bit percolates into the worm and these are used in the animal tissues so on the other hand these endosymbionts are having a safe harbor inside the gut of this animal this is a very interesting type of endosymbiotic relationship and mutualism at the very depth of the ocean where it is completely dark there is no light in there and still this mutualism exists very successful organism 2500 feet below the ocean the roman ecosystem is very common among the romanians animal that have a stomach that is divided into four compartments and they chew a cut why they have developed this process because this is basically eat first digest later kind of evolution why they develop that sometimes when they were grazing many times that due to the predation their eating will be interrupted so they will just run away and then digest later part this is the reason how this relationship evolved so if we just looking at the rumen is the upper part of the stomach and this contains a large diverse population of micro so after the animal ingest the material which is very rich in cellulose they go into the rumen and they are liquefied they are mixed with the saliva and then the animal when he finds time basically chew the cut so the cereal from here is rejurgitated into the mouth they chew it again mixes with saliva and it goes down into the reuben once again and when they're liquefied enough with the action of the other bacteria they also go through this reticulum the second part and from the reticulum they will move into the omasam which is a third part of their digestive tract from the omasum the material is going to move into the abomasum this is the true stomach and from there they will move through the small intestine and we're going to take a look in detail that what kind of a relationship happens here so let's first take a look an overview of that process before we go into the detail so the ruminant microbial community have a mutualistic relationship of course and their specific interaction within the microbial community happens and in cows the carbon dioxide hydrogen and acetate are used by the methanogenic archaea to generate the methane but before that there are lots of different things happen and we're going to talk about that so on the other hand the very end the methanogen synthesized some of these vitamins needed for their animal host and also we're going to see that why they are very important for particular reactions because they efficiently remove that hydrogen that is being produced by some of the previous reactions if they don't some of the reaction will not work so let's take a look at that so the first thing what happens that when the animal chews the material it breaks down the cellulose so one group of bacteria they break down the cellulose and they just break this beta 1-4 linkages and they release the glucose so this glucose is then converted into the acetate then propionate and biturate and biturate propunid acetate these are the organic acids and they also produce these fatty acids and these are the true carbon source for the animal and some of the ruminants when they just produce the fatty acid that's pretty much the end of their rumination they do not go undergo any further processing but in the cows or the cattles the processing is farther even once they produce the fatty acid and the organic acid so what is seen in those that there will be another group of bacteria which we called as an acetogens they are going to oxidize this and they are going to produce this carbon dioxide and hydrogen now this process is also observed in somewhere else which are in the flooded soil where these acidogens live in there as well so why we are trying to bring that example because both of these are kind of a similar relationship there is a process which we called a centrophy that is observed in the ruminants like a cattle that is also observed into this flooded soil where these acidogens produce this carbon dioxide and hydrogen and acetate by the oxidizing ethanol organic acid or other fermentation product now the main problem is that these reactions are thermodynamically not favorable because what happens that from when you try to produce this carbon dioxide hydrogen and acetate from these these reactions have a positive delta g value so as there is a positive delta g value the reaction forward reaction will not it is not favorable you cannot just drive that reaction but somehow this reactions are done the enzymology is very complicated and not well understood as well but it can be done due to some of these methanogenic bacteria like a methanol spirulum which lives along with what they do that immediately when this carbon dioxide and hydrogen is produced they convert this to the methane that due to that this hydrogen level is kept at very low levels when they keep that hydrogen at this very low level the previous reactions which is the oxidation of the organic compounds these reactions can be driven and the overall reaction happens because the carbon dioxide and hydrogen to methane this is a negative delta g value for that reaction exists and that reaction will go always towards the forward direction but that reaction is needed to drive the previous reaction which is the oxidation of the organic compounds only possible due to a low h2 level that is produced in that reaction and that is helped by this methanogens so there is an interesting example that one propunent oxidizing bacteria it's known as palatomeculum thermopropinicum and this uses a flagella not for the motility but what they do that they use a flagellar protein which is known as fid and this serves to basically as a transcription factor for the methanogenic or methanogenesis related transcription of genes in a methanobacter thermoautotrophic is this is a methanogenic bacteria so you can see that there are lots of these reactions that happen the acetogens do need to oxidize these organic compounds the methanogens to live or drive these reactions so this is a very nice symbiotic relationship mutualism that exists not only inside the ruminants like cattle cattle like ruminants but also outside in this flooded soil that we have talked about the next type of symbiosis that we are going to talk about is a cooperation and in this benefits both the organism in a relationship but it is not obligatory and this differs from the mutualism in this way so here we are going to look at the interaction of a nematode which is known as the steiner carbocapsi so this tiny carpocapsi is a relationship with a bacteria which is known as the xenorepdus pneumatophilia so this is the nematode right here and this is a juvenile and inside that you have this green bacteria that is shown in this figure which is the xenorap dust hematophilia now here inside the gut this bacteria lives inside the nematode gut and not expelled because this juvenile is not eating so this now this nematode infects usually some of the caterpillars of the butterfly family in their developmental stage and as the nematode feeds what happens that this xenorap does pneumatophilia is released and they produce toxins that will kill the host but here is the interesting relationship this bacteria produces an antimicrobial compound that prevent other microorganisms from consuming the insect catara so this is a safe haven for the growth of the nematode as well as the bacteria now what you are seeing that the nematode matures and the xenorap does nematophilia releases some of the maturing compounds which help the maturation of the nematodes as well as once they are matured they will mate and they will have all these juveniles once these juveniles come out all these xenoraptors nematophilia will again infect them and live in their gut this is a very interesting cooperative relationship where the bacteria helps a safe haven for the nematode to reproduce and the bacteria finds a safe haven inside the gut of a nematode so after that we are looking at a process which is the commensalism here the one organism benefits and the other is neither harmed nor health so in the commensal thus patient proximity of two partners permit the commensal to feed on the substance captured or ingested by the host or the host commensal often obtains shelter by living either or in the host and also can involve modification of the environment by one organism making more suited for another organism so let's take a look at how we look at the commensalism so the microbial success during the spoilage of milk see here the fermenting bacteria promote the growth of acid tolerant species there are two ways that when these fermenting bacteria do fermentation they are going to produce an environment which is rich in organic acid and these organic acid will allow the growth of acid tolerant species this also is to some extent true that how these fermenting species help in producing say buttermilk or yogurt production so in the yogurt production these fermenting bacteria promote these acid tolerant species which are beneficial bacteria here it is not as also the formation of a biofilm the initial colonizer helps other micro organism to attach that so for example we talked about this biofilament is in a tooth plaque so the initial organism produce that slimy layer on top of the coated tooth with the protein and then other organisms come in and they attach to that and this is also another way that the commensalism work on the other hand the emensalism is a negative impact of one organism or another based on release of a specific product we are going to see some example of antibiotic production by the fungi and how the bacteria can be killed so a classic example of that we are going to take a look at the diagram in the next slide there are some ants which are known as these etyne ants these italian ants this cultivate a garden of fungi belonging to the janus leucoprenus and this is dependent upon an actinobacteria in the genus pseudonycardia that produce inhibitory compounds that prevents the growth of this escoff species this is a predatory fungus for the leukoprenus this will destroy that fungal garden so this is a nice way that the ants do carry this pseudonycardia on their body so that they cannot destroy this leukopenia species so let's take a look at this relationship so this ateen ants cultivate their own nourishment a garden of fungi belonging to this genus leukoprenus and their ability to accomplish this advanced task depends upon this actinobacteria right here actinobacteria in the genus of pseudonycardia this bacteria produce a inhibitory compound right here which stops the growth of this escoff species which is detrimental for this leukoprenus this is a parasite for this fungal garden so uh the ant developed a morphology to carry these actinomycetes the pseudonycardia on their legs and the body on the other hand along with this relationship one two three and four there is a fifth member which is also involved in here this is a actinomycetes east type of fungus which is known as the phyalophora so this phelophora is a predatory fungus which feeds on these pseudonocardia so what is the advantage of that so this allows this prediction prevents the cheaters so what we mean by that when the ant carries these actinomycetes these actinomycetes could be many different ones and the production of these antimicrobial controls which they will produce here as well antimicrobial controls is energetically very demanding so many of these bacteria will not produce these antimicrobial all the time whereas some of their neighbors will so this phala for a species only will feed onto the pseudonycardia which are not producing this antimicrobial because if they are producing the antimicrobial they will not be able to because this is a fungus as well of actinomycetes so if the pseudonocardia is producing antimicrobials this will not be able to feed on those here think about that that in this complex of the pseudocardia you have a mix of population some of these bacteria are producing the antimicrobial agents some of the bacteria are just not producing the anti antimicrobial agents it is just the choice of the bacteria to be energetically conserving the energy versus producing that so this yellow forest species will only be able to eat the microbes or the pseudonycardia which is not producing the antimicrobial agents because that will kill the phialophora as well so the only ones which are producing this antimicrobial are going to thrive here so that means that cheaters means the ones which are not producing the antimicrobial are eliminated from this population a very interesting relationship so after that we are looking at another these are very straightforward the predation so among the microbes involves the predator species that attacks usually kills its prey and at the microbiological level this is also present this vampire caucus has an apibiotic mode of attacking the prey and there are two different types so for example this adaptobacter penetrates the prey and directly consume on the cytoplasmic content whereas this dillo vibrio penetrates the cell wall grows outside the plasma membrane this is essentially in the area which is the periplasmic space then there is a mixococcus this use the gliding motility to creep overtake their prey and release degradative enzymes and these benefits include the increased rate of nutrient cycling but these are predation is also very common at the bacterial level so here are some of the examples that we just saw in the previous slide so here what it shows right right here is a vampyrococcus right here it heads to the outer membrane and the secret this degradative enzymes that will result in lysis and release of the phrase cytoplasmic content in here we are seeing adaptobacter which can penetrate the cell and once they're inside the cell they will consume the cytoplasmic content as well so here in this picture you are seeing the mixococcus xanthus and e coli colony initially you have these two drops and then gradually what happens that this mixococcus moves over and they consume the e coli and this colony becomes clear and you can see that they swarm over the prey and this bacteria has a characteristic by which they moves in waves so the parasitism is one organism the parasite gains whereas the other is harmed which is the host and always some coexistence between the host and the parasite happens and the successful parasites have evolved to coexist in equilibrium with their host because if the balance is upset the host or parasite may die so this is a very interesting relationship so here we are looking at an example of parasitism and in this here you are looking at a photograph of a flattened leaf-shaped genus umbilical area and this is a common folios lichen whereas here you are looking at a thin slice of this under a compound microscope and this is the green algae occur at the thin upper layer and these are the fungal hyphae that make up the rest of the lichen so what is the type of relationship so before going to the control parasitism let's take a look at that what are the partners and what are the definitions so in here the mycobind is a fungal partner which provides water minerals sheltered environment and form substratum for growth of the lichens whereas the phycobind or the algae or the cyanobacterial partner do have the pigments photosynthetic pigments which provides the organic carbon and the oxygen so if you think about this relationship these looks more like a mutualistic relationship compared to a parasitism and why this is a parasitism the reason that we call this as a controlled parasitism because if we independently grow these phycobind which is a algae or the cyanobacteria so without this mycobind this phycobind which is the algae or the cyanobacteria will grow much faster so what happens that in a mutualistic relationship the growth of this microbiome and the and the phi combined both should be dependent on each other so that was the mutualistic relationship so this is not mutualistic why this is not a cooperation so in the cooperation what will happen that if suppose this algae or cyanobacteria is growing and in the absence of the absence of the fungus or the phycobian this algae or the cyanobacteria will grow slower but that's not the case what happens if you do not have the phycobind this will grow faster so basically the microbiome is the parasite of the phycobind so a relationship which looks like more of a mutualistic relationship is actually a control parasitism in the lycan so what is the outcome of this long-term parasitic relationship what happens the parasite loses this unused genomic information because they do survive only inside their host cell and a classic relationship is the acid endosymbine the book neurofedicola we saw that there are many human pathogens also which is mycobacterium lipory causes leprosy mycoplasma genitalia then you have this encephalitis kunikeli and these are some of the human pathogens which do have a very reduced amount of genome due to their parasitic nature the last one that we are looking at is a competition occur when two organisms try to occur use the same resource and there are two possible outcomes of the competition as we talked before that one organism may dominate and this competitive exclusion principle where two organisms share their resource both survive at a lower population level but in one case one organism may dominate and may completely exclude the other one or eliminate the other one where both can live in harmony to a level where they both survive but at a lower population level so these are some of the overview of the relationship that the microbes do have along with other microbes as well as the eukaryotes as well these are the microbial relationships and they rarely lived alone they evolved the specific ways with other organisms which includes the microbes plants and animals as well so that will be the end of this chapter