Cellulose- and Xylan-Degrading Thermophilic Anaerobic Bacteria from Biocompost

Abstract

Nine thermophilic cellulolytic clostridial isolates and four other noncellulolytic bacterial isolates were isolated from self-heated biocompost via preliminary enrichment culture on microcrystalline cellulose. All cellulolytic isolates grew vigorously on cellulose, with the formation of either ethanol and acetate or acetate and formate as principal fermentation products as well as lactate and glycerol as minor products. In addition, two out of nine cellulolytic strains were able to utilize xylan and pretreated wood with roughly the same efficiency as for cellulose. The major products of xylan fermentation were acetate and formate, with minor contributions of lactate and ethanol. Phylogenetic analyses of 16S rRNA and glycosyl hydrolase family 48 (GH48) gene sequences revealed that two xylan-utilizing isolates were related to a Clostridium clariflavum strain and represent a distinct novel branch within the GH48 family. Both isolates possessed high cellulase and xylanase activity induced independently by either cellulose or xylan. Enzymatic activity decayed after growth cessation, with more-rapid disappearance of cellulase activity than of xylanase activity. A mixture of xylan and cellulose was utilized simultaneously, with a significant synergistic effect observed as a reduction of lag phase in cellulose degradation.

Simultaneous saccharification and fermentation of hemicellulose to butanol by a non-sporulating Clostridium species

“…S-2). This phenotype is different from several previously described xylanfermenting thermophiles such as C. thermolacticum (Le Ruyet et al, 1985) and C. clariflavum (Sizova et al, 2011).…”

“…has a great potential for value-added products production from cellulose (Sizova et al, 2011;Yang et al, 2015), while most of the reported studies using hemicellulose compounds of lignocellulosic biomass as a fermentation substrate have been focused on ethanol or hydrogen production rather than on butanol (Tolonen et al, 2011). However, few wild-type strains are known to produce butanol from cellulose or xylan via simultaneous saccharification and fermentation, leaving a need for development of one-step strategies for biobutanol production from lignocellulosic materials.…”

“…Another unique feature that distinguishes strain MF28 from other butanol-producing strains is that it produces only butanol without any by-products such as acetone and ethanol, from the fermentation of xylan. Compared with other known xylan-to-acids isolates (Le Ruyet et al, 1985;Sizova et al, 2011), strain MF28 shows great flexibility in utilizing various carbon substrates derived from lignocelulosic biomass (Table S2). In addition to xylan, xylooligosaccharides (XOS) and xylose, strain MF28 was also found to utilize mannose, galactose and arabinose (all derived from lignocelluloses) to produce butanol, and hence has high economical potential for biomass-based butanol production.…”

Biomethanization of Coal to Obtain Clean Coal Energy: A Review

“…Thermomonospora sp. Cerrena globosum and Aspergillus phoenicus) and bacteria (Bacillus, Bacteroides ovatus, Clostridium clariflavum) are capable of degrading xylans (Sunna and Antranikian, 1997;Abdel-Sater, 2001;Sizova et al, 2011 ). The hemicelluloses are degraded to CO 2 , H 2 O, cell biomass and various small carbohydrate molecules like monomers and dimers.…”

New Approaches for Isolation of Previously Uncultivated Oral Bacteria

“…This is because there are indications that some of the uncultivated species may be involved in a variety of systemic diseases (4,20,44) and likely play an important role in the function of the oral microbial community. We have shown that some previously uncultivable microorganisms can be isolated by mimicking natural growth conditions, using in vivo incubation devices (25,30,34) or via enrichments (17,46,47), and also developed a method for single-cell long-term incubations (S. Buerger et al, submitted for publication). The main objective of this study was to apply these different approaches to the cultivation of oral microorganisms, assess their relative merits, and isolate new species from the list of presently uncultivated taxa.…”