Rhodothermus marinus: physiology and molecular biology

Björnsdóttir, Snædís H.; Blöndal, Thórarinn; Hreggviðsson, Guðmundur Ó.; Eggertsson, Guðmundur; Pétursdóttir, Sólveig K.; Hjörleifsdóttir, Sigríður; Thorbjarnardóttir, Sigrídur H.; Kristjánsson, Jakob K.

doi:10.1007/s00792-005-0466-z

Cited by 56 publications

(45 citation statements)

References 92 publications

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“…Perturbation of the enriched communities by inoculation into cultures with low biomass (1% switchgrass) and amendment with CMC did not significantly alter the community composition of the enrichments, although the glycoside hydrolase activities measured in the supernatant were higher. This observation indicates that biomass loading is a critical component of enrichment cultiva- (2,31,35). Additionally, compost and swine waste-derived microbial communities enriched on microcrystalline cellulose at elevated temperatures under aerobic conditions also contain thermophilic paenibacilli, suggesting that these microbes are critical components of biomass deconstruction under thermophilic aerobic conditions (22,26).…”

Section: Discussionmentioning

confidence: 93%

Glycoside Hydrolase Activities of Thermophilic Bacterial Consortia Adapted to Switchgrass

Gladden

Allgaier

Miller

et al. 2011

Appl Environ Microbiol

113

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Industrial-scale biofuel production requires robust enzymatic cocktails to produce fermentable sugars from lignocellulosic biomass. Thermophilic bacterial consortia are a potential source of cellulases and hemicellulases adapted to harsher reaction conditions than commercial fungal enzymes. Compost-derived microbial consortia were adapted to switchgrass at 60°C to develop thermophilic biomass-degrading consortia for detailed studies. Microbial community analysis using small-subunit rRNA gene amplicon pyrosequencing and short-read metagenomic sequencing demonstrated that thermophilic adaptation to switchgrass resulted in low-diversity bacterial consortia with a high abundance of bacteria related to thermophilic paenibacilli, Rhodothermus marinus, and Thermus thermophilus. At lower abundance, thermophilic Chloroflexi and an uncultivated lineage of the Gemmatimonadetes phylum were observed. Supernatants isolated from these consortia had high levels of xylanase and endoglucanase activities. Compared to commercial enzyme preparations, the endoglucanase enzymes had a higher thermotolerance and were more stable in the presence of 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), an ionic liquid used for biomass pretreatment. The supernatants were used to saccharify [C2mim][OAc]-pretreated switchgrass at elevated temperatures (up to 80°C), demonstrating that these consortia are an excellent source of enzymes for the development of enzymatic cocktails tailored to more extreme reaction conditions.

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Section: Discussionmentioning

confidence: 93%

Glycoside Hydrolase Activities of Thermophilic Bacterial Consortia Adapted to Switchgrass

Gladden

Allgaier

Miller

et al. 2011

Appl Environ Microbiol

113

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“…In previous enrichments from compost with switchgrass and cellulose as the sole carbon source, R. marinus was observed as the dominant Bacteriodetes population (6, 7). R. marinus is a thermophilic Bacteriodetes species that produces high levels of cellulases and hemicellulases when grown on biomass substrates and may occupy a functional niche in the adapted cultures similar to that of strain NYFB (32).…”

Section: Discussionmentioning

confidence: 99%

Substrate-Specific Development of Thermophilic Bacterial Consortia by Using Chemically Pretreated Switchgrass

Eichorst

Joshua

Sathitsuksanoh

et al. 2014

Appl Environ Microbiol

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e Microbial communities that deconstruct plant biomass have broad relevance in biofuel production and global carbon cycling. Biomass pretreatments reduce plant biomass recalcitrance for increased efficiency of enzymatic hydrolysis. We exploited these chemical pretreatments to study how thermophilic bacterial consortia adapt to deconstruct switchgrass (SG) biomass of various compositions. Microbial communities were adapted to untreated, ammonium fiber expansion (AFEX)-pretreated, and ionicliquid (IL)-pretreated SG under aerobic, thermophilic conditions using green waste compost as the inoculum to study biomass deconstruction by microbial consortia. After microbial cultivation, gravimetric analysis of the residual biomass demonstrated that both AFEX and IL pretreatment enhanced the deconstruction of the SG biomass approximately 2-fold. Two-dimensional nuclear magnetic resonance (2D-NMR) experiments and acetyl bromide-reactive-lignin analysis indicated that polysaccharide hydrolysis was the dominant process occurring during microbial biomass deconstruction, and lignin remaining in the residual biomass was largely unmodified. Small-subunit (SSU) rRNA gene amplicon libraries revealed that although the dominant taxa across these chemical pretreatments were consistently represented by members of the Firmicutes, the Bacteroidetes, and Deinococcus-Thermus, the abundance of selected operational taxonomic units (OTUs) varied, suggesting adaptations to the different substrates. Combining the observations of differences in the community structure and the chemical and physical structure of the biomass, we hypothesize specific roles for individual community members in biomass deconstruction.

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“…The affinity of these enzymes for more neutral pH may reflect their origin; for example, R. marinus grows optimally at pH 7.0 [21].…”

Section: Discussionmentioning

confidence: 99%

Microbial Community Structures Differentiated in a Single- Chamber Air-Cathode Microbial Fuel Cell Fueled with Rice Straw Hydrolysate

Serrano‐Ruiz¹

2015

New Microbial Technologies for Advanced Biofuels

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Background: The development of advanced biofuels from lignocellulosic biomass will require the use of both efficient pretreatment methods and new biomass-deconstructing enzyme cocktails to generate sugars from lignocellulosic substrates. Certain ionic liquids (ILs) have emerged as a promising class of compounds for biomass pretreatment and have been demonstrated to reduce the recalcitrance of biomass for enzymatic hydrolysis. However, current commercial cellulase cocktails are strongly inhibited by most of the ILs that are effective biomass pretreatment solvents. Fortunately, recent research has shown that IL-tolerant cocktails can be formulated and are functional on lignocellulosic biomass. This study sought to expand the list of known IL-tolerant cellulases to further enable IL-tolerant cocktail development by developing a combined in vitro/in vivo screening pipeline for metagenome-derived genes. Results: Thirty-seven predicted cellulases derived from a thermophilic switchgrass-adapted microbial community were screened in this study. Eighteen of the twenty-one enzymes that expressed well in E. coli were active in the presence of the IL 1-ethyl-3-methylimidazolium acetate ([C 2 mim][OAc]) concentrations of at least 10% (v/v), with several retaining activity in the presence of 40% (v/v), which is currently the highest reported tolerance to [C 2 mim][OAc] for any cellulase. In addition, the optimum temperatures of the enzymes ranged from 45 to 95°C and the pH optimum ranged from 5.5 to 7.5, indicating these enzymes can be used to construct cellulase cocktails that function under a broad range of temperature, pH and IL concentrations.

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Rhodothermus marinus: physiology and molecular biology

Cited by 56 publications

References 92 publications

Glycoside Hydrolase Activities of Thermophilic Bacterial Consortia Adapted to Switchgrass

Glycoside Hydrolase Activities of Thermophilic Bacterial Consortia Adapted to Switchgrass

Substrate-Specific Development of Thermophilic Bacterial Consortia by Using Chemically Pretreated Switchgrass

Microbial Community Structures Differentiated in a Single- Chamber Air-Cathode Microbial Fuel Cell Fueled with Rice Straw Hydrolysate

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