scholarly journals Cellulose- and Xylan-Degrading Thermophilic Anaerobic Bacteria from Biocompost

2011 ◽  
Vol 77 (7) ◽  
pp. 2282-2291 ◽  
Author(s):  
M. V. Sizova ◽  
J. A. Izquierdo ◽  
N. S. Panikov ◽  
L. R. Lynd
Keyword(s):  
Enrichment Culture ◽  
Cellulose Degradation ◽  
Phylogenetic Analyses ◽  
Glycosyl Hydrolase ◽  
Anaerobic Bacteria ◽  
Xylanase Activity ◽  
Cellulase Activity ◽  
Lag Phase ◽  
Fermentation Products ◽  
Clostridium Clariflavum

ABSTRACTNine 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 aClostridium clariflavumstrain 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.

scholarly journals Colonocyte metabolism shapes the gut microbiota

Science ◽  
2018 ◽  
Vol 362 (6418) ◽  
pp. eaat9076 ◽  
Author(s):  
Yael Litvak ◽  
Mariana X. Byndloss ◽  
Andreas J. Bäumler
Keyword(s):  
Gut Microbiota ◽  
Anaerobic Bacteria ◽  
Enteric Pathogens ◽  
Metabolic Reprogramming ◽  
Human Diseases ◽  
Fermentation Products ◽  
Colonic Microbiota ◽  
Obligate Anaerobic ◽  
Control Switch ◽  
Facultative Anaerobic Bacteria

An imbalance in the colonic microbiota might underlie many human diseases, but the mechanisms that maintain homeostasis remain elusive. Recent insights suggest that colonocyte metabolism functions as a control switch, mediating a shift between homeostatic and dysbiotic communities. During homeostasis, colonocyte metabolism is directed toward oxidative phosphorylation, resulting in high epithelial oxygen consumption. The consequent epithelial hypoxia helps to maintain a microbial community dominated by obligate anaerobic bacteria, which provide benefit by converting fiber into fermentation products absorbed by the host. Conditions that alter the metabolism of the colonic epithelium increase epithelial oxygenation, thereby driving an expansion of facultative anaerobic bacteria, a hallmark of dysbiosis in the colon. Enteric pathogens subvert colonocyte metabolism to escape niche protection conferred by the gut microbiota. The reverse strategy, a metabolic reprogramming to restore colonocyte hypoxia, represents a promising new therapeutic approach for rebalancing the colonic microbiota in a broad spectrum of human diseases.

scholarly journals Zeolite addition to improve biohydrogen production from dark fermentation of C5/C6-sugars and Sargassum sp. biomass

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. M. Silva ◽  
A. A. Abreu ◽  
A. F. Salvador ◽  
M. M. Alves ◽  
I. C. Neves ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Anaerobic Bacteria ◽  
Dark Fermentation ◽  
Inorganic Materials ◽  
Biohydrogen Production ◽  
High Rate ◽  
Continuous Reactor ◽  
Organic Loading Rate ◽  
Fermentation Products ◽  
Zeolite Type

AbstractThermophilic biohydrogen production by dark fermentation from a mixture (1:1) of C5 (arabinose) and C6 (glucose) sugars, present in lignocellulosic hydrolysates, and from Sargassum sp. biomass, is studied in this work in batch assays and also in a continuous reactor experiment. Pursuing the interest of studying interactions between inorganic materials (adsorbents, conductive and others) and anaerobic bacteria, the biological processes were amended with variable amounts of a zeolite type-13X in the range of zeolite/inoculum (in VS) ratios (Z/I) of 0.065–0.26 g g−1. In the batch assays, the presence of the zeolite was beneficial to increase the hydrogen titer by 15–21% with C5 and C6-sugars as compared to the control, and an increase of 27% was observed in the batch fermentation of Sargassum sp. Hydrogen yields also increased by 10–26% with sugars in the presence of the zeolite. The rate of hydrogen production increased linearly with the Z/I ratios in the experiments with C5 and C6-sugars. In the batch assay with Sargassum sp., there was an optimum value of Z/I of 0.13 g g−1 where the H2 production rate observed was the highest, although all values were in a narrow range between 3.21 and 4.19 mmol L−1 day−1. The positive effect of the zeolite was also observed in a continuous high-rate reactor fed with C5 and C6-sugars. The increase of the organic loading rate (OLR) from 8.8 to 17.6 kg m−3 day−1 of COD led to lower hydrogen production rates but, upon zeolite addition (0.26 g g−1 VS inoculum), the hydrogen production increased significantly from 143 to 413 mL L−1 day−1. Interestingly, the presence of zeolite in the continuous operation had a remarkable impact in the microbial community and in the profile of fermentation products. The effect of zeolite could be related to several properties, including the porous structure and the associated surface area available for bacterial adhesion, potential release of trace elements, ion-exchanger capacity or ability to adsorb different compounds (i.e. protons). The observations opens novel perspectives and will stimulate further research not only in biohydrogen production, but broadly in the field of interactions between bacteria and inorganic materials.

scholarly journals Synergistic Effect of Different Plant Cell Wall–Degrading Enzymes Is Important for Virulence of Fusarium graminearum

2017 ◽  
Vol 30 (11) ◽  
pp. 886-895 ◽  
Author(s):  
Maria Chiara Paccanaro ◽  
Luca Sella ◽  
Carla Castiglioni ◽  
Francesca Giacomello ◽  
Ana Lilia Martínez-Rocha ◽  
...  
Keyword(s):  
Cell Wall ◽  
Fusarium Graminearum ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Xylanase Activity ◽  
Cellulase Activity ◽  
Wild Type ◽  
Cell Wall Degrading Enzymes ◽  
Xylanase Production ◽  
Significant Difference

Endo-polygalacturonases (PGs) and xylanases have been shown to play an important role during pathogenesis of some fungal pathogens of dicot plants, while their role in monocot pathogens is less defined. Pg1 and xyr1 genes of the wheat pathogen Fusarium graminearum encode the main PG and the major regulator of xylanase production, respectively. Single- and double-disrupted mutants for these genes were obtained to assess their contribution to fungal infection. Compared with wild-type strain, the ∆pg mutant showed a nearly abolished PG activity, slight reduced virulence on soybean seedlings, but no significant difference in disease symptoms on wheat spikes; the ∆xyr mutant was strongly reduced in xylanase activity and moderately reduced in cellulase activity but was as virulent as wild type on both soybean and wheat plants. Consequently, the ΔpgΔxyr double mutant was impaired in xylanase, PG, and cellulase activities but, differently from single mutants, was significantly reduced in virulence on both plants. These findings demonstrate that the concurrent presence of PG, xylanase, and cellulase activities is necessary for full virulence. The observation that the uronides released from wheat cell wall after a F. graminearum PG treatment were largely increased by the fungal xylanases suggests that these enzymes act synergistically in deconstructing the plant cell wall.

scholarly journals Multi-Omics Study of Keystone Species in a Cystic Fibrosis Microbiome

2021 ◽  
Vol 22 (21) ◽  
pp. 12050
Author(s):  
Cynthia B. Silveira ◽  
Ana G. Cobián-Güemes ◽  
Carla Uranga ◽  
Jonathon L. Baker ◽  
Anna Edlund ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Lung Function ◽  
Sequence Data ◽  
Anaerobic Bacteria ◽  
Keystone Species ◽  
Clinical Diagnostics ◽  
Epifluorescence Microscopy ◽  
Fermentation Products ◽  
Degrading Bacteria

Ecological networking and in vitro studies predict that anaerobic, mucus-degrading bacteria are keystone species in cystic fibrosis (CF) microbiomes. The metabolic byproducts from these bacteria facilitate the colonization and growth of CF pathogens like Pseudomonas aeruginosa. Here, a multi-omics study informed the control of putative anaerobic keystone species during a transition in antibiotic therapy of a CF patient. A quantitative metagenomics approach combining sequence data with epifluorescence microscopy showed that during periods of rapid lung function loss, the patient’s lung microbiome was dominated by the anaerobic, mucus-degrading bacteria belonging to Streptococcus, Veillonella, and Prevotella genera. Untargeted metabolomics and community cultures identified high rates of fermentation in these sputa, with the accumulation of lactic acid, citric acid, and acetic acid. P. aeruginosa utilized these fermentation products for growth, as indicated by quantitative transcriptomics data. Transcription levels of P. aeruginosa genes for the utilization of fermentation products were proportional to the abundance of anaerobic bacteria. Clindamycin therapy targeting Gram-positive anaerobes rapidly suppressed anaerobic bacteria and the accumulation of fermentation products. Clindamycin also lowered the abundance and transcription of P. aeruginosa, even though this patient’s strain was resistant to this antibiotic. The treatment stabilized the patient’s lung function and improved respiratory health for two months, lengthening by a factor of four the between-hospitalization time for this patient. Killing anaerobes indirectly limited the growth of P. aeruginosa by disrupting the cross-feeding of fermentation products. This case study supports the hypothesis that facultative anaerobes operated as keystone species in this CF microbiome. Personalized multi-omics may become a viable approach for routine clinical diagnostics in the future, providing critical information to inform treatment decisions.

scholarly journals Phenylacetic and Phenylpropionic Acids Do Not Affect Xylan Degradation by Ruminococcus albus

2003 ◽  
Vol 69 (11) ◽  
pp. 6954-6958 ◽  
Author(s):  
Carine Reveneau ◽  
Sarah E. Adams ◽  
M. A. Cotta ◽  
M. Morrison
Keyword(s):  
Growth Medium ◽  
Cellulose Degradation ◽  
Xylanase Activity ◽  
Ruminococcus Albus ◽  
Carbohydrate Source ◽  
Ruminal Fluid ◽  
Xylan Degradation ◽  
Multiple Strains

ABSTRACT Since the addition of either ruminal fluid or a combination of phenylacetic and phenylpropionic acids (PAA/PPA) has previously been shown to dramatically improve cellulose degradation and growth of Ruminococcus albus, it was of interest to determine the effects of these additives on xylan-grown cultures. Although cell-bound xylanase activity increased when either PAA/PPA or ruminal fluid was added to the growth medium, total xylanase did not change, and neither of these supplements affected the growth or xylan-degrading capacity of R. albus 8. Similarly, neither PAA/PPA nor ruminal fluid affected xylan degradation by multiple strains of R. albus when xylan prepared from oat spelts was used as a carbohydrate source. These results show that the xylanolytic potential of R. albus is not conditional on the availability of PAA/PPA or other components of ruminal fluid.

scholarly journals Heterotrimeric G-Protein Signaling Is Required for Cellulose Degradation in Neurospora crassa

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
Author(s):  
Logan A. Collier ◽  
Arit Ghosh ◽  
Katherine A. Borkovich
Keyword(s):  
G Protein ◽  
Cellulose Degradation ◽  
Cellulase Activity ◽  
Cellulase Production ◽  
Camp Signaling ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
Wild Type ◽  
Posttranscriptional Control ◽  
Heterotrimeric G Protein Signaling

ABSTRACT The filamentous fungus Neurospora crassa decomposes lignocellulosic biomass to generate soluble sugars as carbon sources. In this study, we investigated a role for heterotrimeric G-protein signaling in cellulose degradation. Loss of the Gα subunit genes gna-1 and gna-3, the Gβ subunit genes gnb-1 and cpc-2, the Gγ gene gng-1, or the gene for downstream effector adenylyl cyclase (cr-1) resulted in loss of detectable cellulase activity. This defect was also observed in strains expressing a constitutively active version of gna-3 (gna-3Q208L). We found that GNA-1 levels are greatly reduced in Δgna-3, Δgnb-1, and Δgng-1 strains, likely contributing to cellulase defects in these genetic backgrounds. The observation that gna-3Q208L Δgnb-1 strains exhibit cellulase activity, despite greatly reduced levels of GNA-1 protein, is consistent with positive control of cellulase production by GNA-3 that is manifested in the absence of gnb-1. Expression patterns for five cellulase genes showed that Δgna-1, Δgnb-1, and Δgna-3 mutants produce less cellulase mRNA than the wild type, consistent with transcriptional regulation. Δcpc-2 mutants had wild-type levels of cellulase transcripts, suggesting posttranscriptional control. In contrast, results for Δcr-1 mutants support both transcriptional and posttranscriptional control of cellulase activity by cAMP signaling. Cellulase activity defects in Δgna-3 mutants were fully remediated by cAMP supplementation, consistent with GNA-3 operating upstream of cAMP signaling. In contrast, cAMP addition only partially corrected cellulase activity defects in Δgna-1 and Δgnb-1 mutants, suggesting participation of GNA-1 and GNB-1 in additional cAMP-independent pathways that control cellulase activity. IMPORTANCE Filamentous fungi are critical for the recycling of plant litter in the biosphere by degrading lignocellulosic biomass into simpler compounds for metabolism. Both saprophytic and pathogenic fungi utilize plant cell wall-degrading enzymes to liberate carbon for metabolism. Several studies have demonstrated a role for cellulase enzymes during infection of economically relevant crops by fungal pathogens. Especially in developing countries, severe plant disease means loss of entire crops, sometimes leading to starvation. In this study, we demonstrate that G-protein signaling is a key component of cellulase production. Therefore, understanding the role of G-protein signaling in the regulation of the unique metabolism of cellulose by these organisms can inform innovations in strain engineering of industrially relevant species for biofuel production and in combatting food shortages caused by plant pathogens.

scholarly journals Promotion of Biogasification Efficiency by Pretreatment and Bioaugmentation of Corn Straw with Microbial Consortium

2019 ◽  
Vol 118 ◽  
pp. 01032
Author(s):  
Qili Zhu ◽  
Yanwei Wang ◽  
Furong Tan ◽  
Bo Wu ◽  
Lichun Dai ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Surface Structure ◽  
Degradation Rate ◽  
Microbial Consortium ◽  
Biogas Production ◽  
Cellulose Degradation ◽  
Cellulase Activity ◽  
Corn Straw ◽  
Structure Characteristics ◽  
Anaerobic Microbial Consortium

To better understand the comparative effects between pretreatment and bioaugmentation methods on the promotion of corn straw biogasification efficiency, we analysed the cellulase activity, cellulose degradation rate, surface structure characteristics, and biogas production of corn straw that had been pretreated with aerobic microbial consortium (AMC). In addition, we also studied the effect of bioaugmentation using anaerobic microbial consortium (ANMC) on corn straw biogasification efficiency. The results from our study demonstrated that the cumulative methane generated from AMC and ANMC were 233.09 mL·g-1 VS and 242.56 mL·g-1 VS, which was increased compared to the control by 6.89% and 11.23%, respectively. We also observed that ANMC could also function to dramatically promote methane content during the anaerobic digestion of corn straw. This study demonstrated that AMC and ANMC were both able to promote the biogasification efficiency of corn straw, however, ANMC was found to perform better compared to AMC.

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