Tag Archives: trichoderma

Brown rotting fungal genome published

ResearchBlogging.orgPostia placenta genome is now published in early edition of PNAS.   Brown rotting fungi are import part of the cellulose degrading ecology of the forest as well (hopefully) providing some enzymes that will help in the ligin to biofuels process. Brown rotters break down cellulose but cannot break down lignin or lignocellulose while white rotters (like the previously sequenced Phanerochaete chrysosporium) are able to break down the lignin.  This fungus was chosen for sequencing as it is another potentially helpful fungus in the war on sugars (turning them into fuels) including recently published Trichoderma reesei and 1st basidiomycete genome Phanerochaete (all incidentally with the Diego Martinez as first author – go Diego!). It is also helpful to contrast the white and brown rotters to understand how their enzyme capabilities have changed and how these different lifestyles evolved.  There had been some issues with the initial assembly of this genome which is basically twice as big as one would expect because the dikaryon genome was sequenced – this is where two nuclei with different genomes are present as the result of fusion between two parents of opposite mating types.  When genome sequenced is performed it is hard to assemble these into a single assembly since there are really two haplotypes present.  So these haplotypes have to be sorted out to obtain the gene ‘count’ for the organism for those who like simple numbers. This is a similar situation to the Candida albicans genome, although those haplotypes are much more similar.  The main problem is that one has to generate twice as much sequence to get the same coverage of each haplotype without playing some tricks to collapse them into a consensus and them afterwards separate the haplotypes back out.  At any rate, this sequenced provided a good summary of the gene content and thus metabolic and enzymatic capabilities to match up functional data collected from LC/MS and transcriptional profiling. 

There are several other rotting fungi that are nearly done at JGI (but the task of writing and coordinating the analyses for the papers are ongoing!) include Schizophyllum commune and Pleurotus ostreatus. There are also several more mycorrhizal and plant pathogenic basidiomycete fungi as well as some classic model systems that have finished genomes and are in the process of finalizing papers.  It is an exciting time that is just beginning as these genome and transcriptional data are integrated and compared for their different ecological, morphological, and metabolic capabilities.

The article is unfortunately not Open Access so I haven’t even read it from home yet, but pass along this news to you, dear reader. Will get a chance to read through more than the abstract to see what glistening gems have been extracted from this genomic endeavor.
D. Martinez, J. Challacombe, I. Morgenstern, D. Hibbett, M. Schmoll, C. P. Kubicek, P. Ferreira, F. J. Ruiz-Duenas, A. T. Martinez, P. Kersten, K. E. Hammel, A. V. Wymelenberg, J. Gaskell, E. Lindquist, G. Sabat, S. S. BonDurant, L. F. Larrondo, P. Canessa, R. Vicuna, J. Yadav, H. Doddapaneni, V. Subramanian, A. G. Pisabarro, J. L. Lavin, J. A. Oguiza, E. Master, B. Henrissat, P. M. Coutinho, P. Harris, J. K. Magnuson, S. E. Baker, K. Bruno, W. Kenealy, P. J. Hoegger, U. Kues, P. Ramaiya, S. Lucas, A. Salamov, H. Shapiro, H. Tu, C. L. Chee, M. Misra, G. Xie, S. Teter, D. Yaver, T. James, M. Mokrejs, M. Pospisek, I. V. Grigoriev, T. Brettin, D. Rokhsar, R. Berka, D. Cullen (2009). Genome, transcriptome, and secretome analysis of wood decay fungus Postia placenta supports unique mechanisms of lignocellulose conversion Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0809575106

Trichoderma reesei genome paper published

TrichodermaThe Trichoderma reesei genome paper was recently published in Nature Biotechnology from Diego Martinez at LANL with collaborators at JGI, LBNL, and others. This fungus was chosen for sequencing because it was found on canvas tents eating the cotton material suggesting it may be a good candidate for degrading cellulose plant material as part of cellulosic ethanol or other biofuels production.  The fungus also has starring roles in industrial processes like making stonewashed jeans due to its prodigious cellulase production.

The most surprising findings from the paper include the fact that there are so few members of some of the enzyme families even though this fungus is able to generate enzymes with so much cellulase activity. The authors found that there is not a significantly larger number of glucoside hydrolases which is a collection of carbohydrate degrading enzymes great for making simple sugars out of complex ones. In fact, several plant pathogens compared (Fusarium graminearum and Magnaporthe grisea) and the sake fermenting Aspergillus oryzae all have more members of this family than does.  T. reesei has almost the least (36) copies of a cellulose binding domain (CBM) of any of the filamentous ascomycete fungi.  They used the CAZyme database (carbohydrate active enzymes) database which has done a fantastic job building up profiles of different enzymes involved in carhohydrate degradation binding, and modifications.

Whether T. reesei is really the best cellulose degrading fungus is definitely an open question.  That it works well in the industrial culture that it has been utilized in is important, but there may be other species of fungi with improved cellulase activity and who may in fact have many more copies of cellulases.  So it will be good to add other fungi to the mix with quantitative information about degradation to try and glean what are the most important combination of enzymes and activities.

One technical note.  The comparison of copy number differences employed in the paper is a simple enough Chi-Squared, work that I’ve done with Matt Hahn and others include a gene family size comparison approach that also taked into account phylogenetic distances and assumes a birth-death process of gene family size change.  It would be great to apply the copy number differences through this or other approaches that just evaluate gene trees for these domains to see where the differences are significant and if they can be polarized to a particular branch of the tree.

So will this genome sequence lead to cheaper, better biofuel production? Certainly it provides an important toolkit to start systematically testing individual cellulase enzymes. It’s hard to say how fast this will make an impact, but the work of JBEI and a host of other research groups and biotech companies are going to be able to systematically test out the utility of these individual enzymes.

There is also evolutionary work by other groups on the evolution of these Hypocreales fungi trying to better define when biotrophic and heterotrophic transitions occurred to sample fungi with different lifestyles that might have different cellulase enyzmes that may not have been observed. Defining the relationships of these fungi and when and how many times transitions to lifestyles occurred to choose the most diverse fungi may be an important part of discovering novel enzymes.

Also see

Martinez, D., Berka, R.M., Henrissat, B., Saloheimo, M., Arvas, M., Baker, S.E., Chapman, J., Chertkov, O., Coutinho, P.M., Cullen, D., Danchin, E.G., Grigoriev, I.V., Harris, P., Jackson, M., Kubicek, C.P., Han, C.S., Ho, I., Larrondo, L.F., de Leon, A.L., Magnuson, J.K., Merino, S., Misra, M., Nelson, B., Putnam, N., Robbertse, B., Salamov, A.A., Schmoll, M., Terry, A., Thayer, N., Westerholm-Parvinen, A., Schoch, C.L., Yao, J., Barbote, R., Nelson, M.A., Detter, C., Bruce, D., Kuske, C.R., Xie, G., Richardson, P., Rokhsar, D.S., Lucas, S.M., Rubin, E.M., Dunn-Coleman, N., Ward, M., Brettin, T.S. (2008). Genome sequencing and analysis of the biomass-degrading fungus Trichoderma reesei (syn. Hypocrea jecorina). Nature Biotechnology DOI: 10.1038/nbt1403