| Author |
Nou NO, Covington JK, Lai D, Mayali X, Seymour CO, Johnston J, Jiao JY, Buessecker S, Mosier D, Muok AR, Torosian N, Cook AM, Briegel A, Woyke T, Eloe-Fadrosh E, Shapiro N, Bryan SG, Sleezer S, Dimapilis J, Gonzalez C, Gonzalez L, Noriega M, Hess M, Carlson RP, Liu L, Li MM, Lian ZH, Zhu S, Liu F, Sun X, Gao B, Mewalal R, Harmon-Smith M, Blaby IK, Cheng JF, Weber PK, Grigorean G, Li WJ, Dekas AE, Pett-Ridge J, Dodsworth JA, Palmer M, Hedlund BP.
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| Abstract |
Few aerobic hyperthermophilic microorganisms degrade polysaccharides. Here, we describe the genome-enabled enrichment and optical tweezer-based isolation of an aerobic polysaccharide-degrading hyperthermophile, Fervidibacter sacchari, previously ascribed to candidate phylum Fervidibacteria. F. sacchari uses polysaccharides and monosaccharides for growth at 65-87.5 °C and expresses 191 carbohydrate-active enzymes (CAZymes) according to RNA-Seq and proteomics, including 31 with unusual glycoside hydrolase domains (GH109, GH177, GH179). Fluorescence in-situ hybridization and nanoscale secondary ion mass spectrometry confirmed rapid assimilation of 13C-starch in spring sediments. Purified GHs were optimally active at 80-100 °C on ten different polysaccharides. Finally, we propose reassigning Fervidibacteria as a class within phylum Armatimonadota, along with 18 other species, and show that a high number and diversity of CAZymes is a hallmark of the phylum, in both aerobic and anaerobic lineages. Our study establishes Fervidibacteria as hyperthermophilic polysaccharide degraders in terrestrial geothermal springs and suggests a broad role for Armatimonadota in polysaccharide catabolism.
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