Transcript

Speaker 1:        Spectrum's. Next. 

Speaker 2:        N. N. N. N. 

Speaker 3:        [inaudible].

Speaker 1:        Welcome to spectrum the science and technology show on k a l x, [00:00:30 ] Berkeley, a biweekly 30 minute program, bringing you interviews, featuring bay area scientists and technologists as well as a calendar of local events and news. 

Speaker 4:        Good afternoon. I'm Rick Karnofsky. Brad swift and I are the hosts of today's show. Today we're talking with doctors, Tonya Wilkie and Chris Rink of the Department of Energy Joint Genome Institute in Walnut Creek. They recently published an article entitled insights into the Phylogeny and coding potential [00:01:00 ] of microbial dark matter in which they have to characterized through relationships between 201 different genomes and identified some unique genomic features. Tonya and Chris, welcome to spectrum. 

Speaker 5:        Thanks for having us. Thank you. 

Speaker 4:        So Tanya, what is microbial dark matter? 

Speaker 5:        We like to take life as we know it and put it in an evolutionary tree in a tree of life. And what this assists us is to figure out the evolutionary histories of organisms and the relationships between [00:01:30 ] related groups of organisms. So what does this mean? It's to say we take microbial diversity as we know it on this planet and we place it in this tree of life. What you will find is that there will be some major branches in this tree, about 30 of them, and we call these major branches Fila that are made up of organisms that you can cultivate. So we can grow them on plates in the laboratory, we can grow them in Allen Meyer, flask and liquid media. We can study that for CLG. We can figure out what substrates they metabolize, [00:02:00 ] we can figure out how they behave under different conditions. 

Speaker 5:        Many of them we can even genetically modify. So we really know a lot about these organisms and we can really figure out, you know, how do they function, what are the genetic underpinnings that make them function the way they do in the laboratory and also in the environment where they come from. So now coming back to this tree of life, if you keep looking at this tree of life, uh, we will find at least another 30 off these major branches that we refer to as [00:02:30 ] Canada. Dot. Sila and these branches have no cultivators, representatives, so all the organisms that make up these branches, we have not yet been able to cultivate in the laboratory. We call these kind of dot, Fila or microbial dark matter. And the term dark matter. All biological dark matter has been coined by the Steve Craig Laboratory at Stanford University when they published the first genomes after a candidate, phylum TM seven. We know that dark matter is in most if not all [00:03:00 ] ecosystems. So we find it in most ecosystems, but to get at their complete genetic makeup. That's the key challenge. 

Speaker 4:        Yeah. And if you, if you want to push it through the extreme, there are studies out there estimating the number of bacteria species they are and how many we can cultivate. And the result is all there. The estimation of the studies we can cultivate about, you know, one or 2% of all the microbial species out there. So basically nine to 9% is still out there and we haven't even looked at it. So this really, this major on culture microbes and majority is [00:03:30 ] still waiting out there to be explored. So that sort of carries on the analogy to cosmological dark matter in which there's much more of it than what we actually see and understand. Right. 

Speaker 5:        So how common and how prevalent are, are these dark matter organisms? Yeah, that's a really good question. So in some environments they are what we would consider the rabbi biosphere. So they are actually at fairly low abundance, but our methods are sensitive enough to still pick them up. [00:04:00 ] In other environments. We had some sediment samples where some of these candidate file, our, actually what we would consider quite abandoned, it's a few percent, let's say 2% of opiate candidate phylum that to us, even 2% is quite abandoned. Again, you have to consider the whole community. And if one member is a 2%, that's, that's a pretty dominant community members. So I'd arise from environment, environment 

Speaker 4:        and Chris, where were samples collected from? So altogether we sampled nine sampling sites all over the globe [00:04:30 ] and we tried to be as inclusive as possible. So we had marine samples, freshwater samples, sediment samples, um, some samples from habitats with very high temperatures and also a sample from a bioreactor. And there were a few samples among them that for which we had really great hopes. And among them were um, samples from the hot vans from the bottom of Pacific Ocean. The samples we got were from the East Pacific virus sampling side, and that's about 2,500 meters below the store phase. And [00:05:00 ] the sample there, you really need a submersible that's a small submarine and you can launch from a research vessel. In our case, those samples were taken by Elvin from the woods hole oceanographic institution and now you have a lot of full Canik activity and also the seawater seeps into the earth crust goes pretty deep and gets heated up. 

Speaker 4:        And when it comes back out as a hydrothermal event, it has up to [inaudible] hundred 50 to 400 degrees Celsius. And it is enriched in chemicals such as a sulfur or iron. [00:05:30 ] It makes us immediately with the surrounding seawater, which is only about a two degrees Celsius. So it's a very, it's a very challenging environment because you have this gradient from two degrees to like 400 degrees within a few centimeters and you have those chemicals that uh, the organisms, the micro organisms could use blast. There is no sunlight. So we thought that's a very interesting habitat to look for. Microbial, dark matter. There were several samples. That's a to us. One of them is the Homestake [00:06:00 ] mine in South Dakota and that's an old gold mine that is not used anymore since 2002 but are there still scientific experiments going on there? It's a very deep mine, about 8,000 feet deep and we could all sample from about 300 feet. 

Speaker 4:        And we were surprised about this Ikea diversity we found in those samples. There were a few Akia that were not close to any, I don't know another key out there for some of them. We even had to propose new archaeal Fila. Stepping back a bit, Chris, [00:06:30 ] can you tell us more about Ikea and perhaps the three domains of life? The three domains were really established by Culver's with his landmark paper in 1977 and what he proposed was a new group of Derek here. So then he had all together three domains. You had the bacteria and archaea and the eukaryotes, the eukaryote state. There are different one big differences to have the nucleus, right? They have to DNA in the nucleus and it also includes all the higher taxa. But then you have also their key and the bacteria. [00:07:00 ] And those are two groups that only single cell organisms, but they are very distant related to each other, the cell envelope, all. And also the cell duplication machinery of the archaea is closer to the eukaryotes than it is to the bacteria. 

Speaker 5:        Yeah, and it's interesting, I mean Ikea, I guess we haven't sequenced some that much yet, but Ikea are very important too, but people are not aware of them. They know about bacteria, but Ikea and maybe because there aren't any RKO pathogen [00:07:30 ] and we'd like to think about bacteria with regards to human health, it's very important. That's why most of what we sequence are actually pathogens, human pathogens. So we sequence, I don't know how many strains of your senior pastors and other pathogenic bacteria, but archaea are equally important, at least in the environment. But because we rarely find them associated with humans, we don't really think about archaea much. Our people aren't really aware of Ikea. 

Speaker 4:        Talk about their importance, 

Speaker 5:        the importance [00:08:00 ] in the environment. So Ikea are, for example, found in extreme environments. We find them in Hydro Soma environments. We find them in hot springs. Uh, we, they have, they have biotechnological importance and not a lot of, quite useful in enzymes that are being used in biotechnology are derived from Ikea in part because we find them in these extreme environments and hot environments and they have the machinery to deal with this temperature. So they have enzymes that function [00:08:30 ] properly at high temperature and extreme conditions, really extreme on the commerce extreme or fields. And that makes them very attractive bio technologically because some of these enzymes that we would like to use should be still more tolerant or should have these features that are sort of more extreme. Um, so we can explain it them for a biotech technological applications. [inaudible] 

Speaker 6:        [inaudible] [00:09:00 ] you are listening to spectrum on k l x Berkeley. I'm Rick [inaudible] and I'm talking with Kanya vulgate and Chris, her and Kate about using single cell genomics. You're expand our knowledge that the tree of life, 

Speaker 5:        [00:09:30 ] so again, we called up a range of different collaborators and they were all willing t