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Cellulolytic bacteria from cattle rumen with ability to hydrolyze cellulose rich biomass were explored. The study selected Paenibacillus polymyxa ND24 from 847 isolates as the most potent strain, which can efficiently produce cellulase by utilizing sugarcane bagasse, rice straw, corn starch, CMC, and avicel as a sole carbon source. On annotation of P. polymyxa ND24 genome, 116 members of glycoside hydrolase (GH) family from CAZy clusters were identified and the presence of 10 potential cellulases was validated using protein folding information. Cellulase production was further demonstrated at lab-scale 5-L bioreactor exhibiting maximum endoglucanase activity up to 0.72 U/mL when cultivated in the medium containing bagasse (2% w / v ) after 72 h. The bagasse hydrolysate so produced was further utilized for efficient biogas production. The presence of diverse hydrolytic enzymes and formidable cellulase activity supports the use of P. polymyxa ND24 for cost-effective bioprocessing of cellulosic biomass.

Porang rhizosphere harbors a diverse range of bacteria, which play pivotal roles in driving essential soil processes that, in turn, regulate the overall functionality of terrestrial ecosystems. This study primarily focuses on the PGPR (Plant Growth-Promoting Rhizobacteria) properties of these strains, which possess cellulolytic, nitrogen-fixing, and phosphate-solubilizing abilities. The research was carried out by isolating bacteria from the porang rhizosphere. The isolated bacteria were then tested for their ability to hydrolyze cellulose, fix nitrogen and dissolve phosphate. Apart from that, a capability test was also carried out in producing IAA. Isolate UPc22 consistently exhibited higher cellulolytic activity, as evidenced by both cellulose hydrolyzing efficiency cellulase activity and IAA production. UPn24 demonstrated the most active nitrogen-fixing activity, with consistently higher mean values for both activity efficiency and nitrogenase activity quantification. UPp36 displayed notably high phosphate-solubilization efficiency values in plate assays. In enzymatic assays, isolate UPp36 exhibited the highest activity. Based on that assays, 15 potential isolates were selected for each group. For cellulolytic bacteria, the selected isolates were similar with Rhizobium cellulosilyticum strain H349, Paenibacillus pinihumi strain CM6, Stenotrophomonas maltophilia strain JCM 1988, Paenibacillus cellulositrophicus strain P-21, and Bacillus thuringiensis strain RG17-11. For nitrogen-fixing bacteria, the chosen isolates comprise Azotobacter vinelandii strain PWB, Delftia lacustris strain R-54356, Bacillus subtilis strain A14d3B, Pseudomonas stutzeri strain DSM 5190T, and Klebsiella quasipneumoniae strain KqPF26. For phosphate-solubilizing bacteria, the selected isolates was similar with Pseudomonas putida strain GPo1, Bacillus magterium strain WF6, Bacillus licheniformis strain 51.5, Klebsiella singaporensis strain 01A065, and Burkholderia cepacia strain PRS.

The aim of the study was to isolate and identify a highly efficient cellulolytic bacteria strain that can be used in acidic environments, and then investigate its cellulase production characteristics for the effective utilization of agricultural waste. For this purpose, we set a series of isolation and screening steps, 21 strains were isolated from soil, and an acidophilic strain labeled as B13-2 with high cellulase production was screened using the Gram’ iodine method and cellulase activity assay; it was identified as Raoultella terrigena. Lastly, the culture conditions such as incubation time, incubation temperature, pH, carbon sources, nitrogen sources, and inoculum size were optimized via single-factor experiments, and on this basis, the cellulase production of strain B13-2 was optimized using response surface methodology with cellulase activity as the optimization goal. The results of the response surface optimization showed that the optimum incubation time is 3.1 days, the optimum temperature is 29.9 °C, the optimum pH is 4.1, and the optimum inoculum size is 1.50%, the cellulase activity reached a maximum of 13.503 U/mL, which was about 140% higher than that before optimization. In particular, strain B13-2 had higher cellulase production when rice straws were used as the natural carbon source. Meanwhile, the SEM pictures demonstrated that the surface of the substrate rice straws in an acidic buffer with strain B13-2 was uneven, with larger holes than in the neutral buffer after incubation. It further proved that this strain has a stronger ability to degrade cellulose under acidic conditions. The B13-2 is a kind of acidophilic cellulolytic bacteria. Therefore, it has the potential to be developed into a silage additive agent and provides a high-quality strain resource for the high-value biotransformation of agricultural waste and lays a certain foundation for the sustainable development of agricultural cultivation.

The ecology of cellulolytic bacteria in bulk soil is still relatively unknown. There is still only a handful of papers on the abundance and diversity of this group of bacteria. Our study aimed to determine the impact of various crop management systems and farmyard manure (FYM) fertilization on the abundance of cellulolytic and potentially cellulolytic spore-forming bacteria (SCB). The study site was a nearly 100-year-old fertilization experiment, one of the oldest still active field trials in Europe. The highest contents of total carbon (TC) and total nitrogen (TN) were recorded in both five-year rotations. The abundances of SCB and potential SCB were evaluated using classical microbiological methods, the most probable number (MPN), and 16S rRNA Illumina MiSeq sequencing. The highest MPN of SCB was recorded in soil with arbitrary rotation without legumes (ARP) fertilized with FYM (382 colony-forming units (CFU) mL−1). As a result of the bioinformatic analysis, the highest values of the Shannon–Wiener index and the largest number of operational taxonomic units (OTUs) were found in ARP-FYM, while the lowest in ARP treatment without FYM fertilization. In all treatments, those dominant at the order level were: Brevibacillales (13.1–43.4%), Paenibacillales (5.3–36.9%), Bacillales (4.0–0.9%). Brevibacillaceae (13.1–43.4%), Paenibacillaceae (8.2–36.9%), and Clostridiaceae (5.4–11.9%) dominated at the family level in all tested samples. Aneurinibacillaceae and Hungateiclostridiaceae families increased their overall share in FYM fertilization treatments. The results of our research show that the impact of crop management types on SCB was negligible while the actual factor shaping SCB community was the use of FYM fertilization.

[...]supplementing RPB with PPE improved nitrogen metabolism of fattening lambs, however, it decreased population of rumen cellulolytic bacteria R flavefaciens. © 2019 Urmia University. Many studies indicated that tannins selectively inhibit the growth of microorganisms in the gastrointestinal tracts depending on the type of tannins.5,6,15 At high concentration level (i.e., more than 50.00 g kg-1 dietary DM), tannins have significant inhibitory effects on the fibrolytic bacterial in the rumen depended on the type of tannins, thus, it may decrease fiber digestibility.10 It has been suggested that phenolic monomers decrease cellulose and xylan digestion by inhibiting the attachment of ruminal cellulolytic bacteria such as F. succinogenesto to fiber particles.16 Reduction of cellulolytic bacteria population by dietary supplementation with tannins has been shown in vivo and in vitro. 17,18 Recently the dynamics of cellulolytic bacterial populations (i.e., F. succinogenes, R. albus and R. flavefaciens) in response to dietary changes have been studied using targeting 16S rRNA gene by realtime PCR in ruminants.17,19 Thus, the objective of this study was to investigate the effect of RPB treated with tannins extracted from PP (PPE) on changing total and cellulolytic bacteria population by real-time PCR technique and to determine the effect of this process on the rumen fermentation parameters on male Arabian lambs. [...]the produced heat processed broiler litter was ground to pass a 6 mm sieve. Discussion Reduction of total bacteria, R albus and F. succinogenes in the diets containing RPB treated with PPE might be due to binding tannins of PPE to substrate cell wall resulting in a reduction in the availability of binding sites on cell wall for rumen microbes.32 Moreover, previous report suggested that tannins may form strong complexes with substrates and reduce adhesion of microbes.33 Tannins also are known for their antimicrobial activity either on cellulolytic or proteolytic bacteria,34 as reduction of microbial attachment caused by tannin is supported by the reduction ruminal microbial population.32 Bae et al. indicated that addition of tannin in pure cultures in vitro resulted in the formation of tannin-protein complexes on the cell surface of F. succinogenes, suggesting interfere of tannin with the adhesion process.35 Therefore, based on Molan et al., it is likely that the reduction in microbial attachment is related to binding of tannin to bacterial cell surface.36 Similar to results obtained in the present study, tannins have reduced cellulolytic bacteria population in vivo 37 and in vitro by inhibiting microbial growth.18 Bento et al. observed reduction of microbial attachment when supplementing cellulose with mimosa tannin compared to cellulose alone.38 Filter paper digestion and endoglucanase activity of F. succinogenes, a predominant ruminal cellulolytic bacterial species, also were inhibited in a dose dependent manner by purified condensed tannins (CT).35 In the present study, both extracellular and cell-associated endoglucanase activities were completely inhibited by 400 gg CT per mL.

Returning crop residues is a possible practice for balancing soil carbon (C) loss. The turnover rate of organic C from crop residues to soil C is dependent on soil microbial community dynamics. However, the relationship between any temporal changes in the soil microbial community after crop straw inputs and the dynamics of straw-C distribution in the soil organic carbon (SOC) pool remains unclear. The present study investigated the allocation of straw-C into soil dissolved organic carbon (DOC), microbial biomass carbon (MBC), particulate organic carbon (POC) and mineral-associated organic carbon (MaOC) using stable isotope probing, as well as the temporal changes in the soil bacterial and fungal communities using high-throughput sequencing. After the first 180 days of straw decomposition, approximately 3.93% and 19.82% of straw-C was transformed into soil MaOC and POC, respectively, while 0.02% and 2.25% of straw-C was transformed into soil DOC and MBC, respectively. The temporal change of the soil microbial community was positively correlated with the dynamics of straw-C distribution to SOC (R > 0.5, P  < 0.05). The copiotrophic bacteria (e.g., Streptomyces , Massilia and Sphingobacterium ), cellulolytic bacteria and fungi (e.g., Dyella and Fusarium , Talaromyces) , acidophilic bacteria (e.g., Edaphobacter and unclassified Acidobacteriaceae ), denitrifying and N-fixing microbes (e.g., Burkholderia-Paraburkholderia , Paraphaeosphaeria and Bradyrhizobium) , and fungi unclassified Sordariomycetes were significantly correlated with straw-C distribution to specific SOC fractions ( P  < 0.05), which explained more than 90% of the variation of straw-C allocation into soils. Copiotrophic, certain cellulolytic and denitrifying microbes had positively correlated with DOC- and MaOC-derived from straw, and other cellulolytic fungi (e.g., Talaromyces ) and specific bacteria (e.g. Bradyrhizobium ) were positively correlated with POC-derived from straw. Our results highlight that the temporal change of soil microbial community structure well reflects the conversion and distribution process of straw-C to SOC fractions.

As major structural components of plant cell walls, cellulose and hemicellulose are degraded and fermented by anaerobic microbes in the rumen to produce volatile fatty acids, the main nutrient source for the host. Cellulose degradation is carried out primarily by specialist bacteria, with additional contributions from protists and fungi, via a variety of mechanisms. Hemicelluloses are hydrolyzed by cellulolytic bacteria and by generalist, non-cellulolytic microbes, largely via extracellular enzymes. Cellulose hydrolysis follows first-order kinetics and its rate is limited by available substrate surface area. Nevertheless, its rate is at least an order of magnitude more rapid than in anaerobic digesters, due to near-obligatory adherence of microbial cells to the cellulose surface, and a lack of downstream inhibitory effects; in the host animal, fiber degradation rate is also enhanced by the unique process of rumination. Cellulolytic and hemicellulolytic microbes exhibit intense competition and amensalism, but they also display mutualistic interactions with microbes at other trophic levels. Collectively, the fiber-degrading community of the rumen displays functional redundancy, partial niche overlap, and convergence of catabolic pathways that all contribute to stability of the ruminal fermentation. The superior hydrolytic and fermentative capabilities of ruminal fiber degraders make them promising candidates for several fermentation technologies.

Rice ( Oryza sativa L.) straw, an agricultural waste of high yield, is a sustainable source of fermentable sugars for biofuel and other chemicals. However, it shows recalcitrance to microbial catalysed depolymerization. We herein describe development of thermotolerant microbial consortium (RSV) from vermicompost with ability to degrade rice straw and analysis of its metagenome for bacterial diversity, and lignocellulolytic carbohydrate active enzymes (CAZymes) and their phylogenetic affiliations. RSV secretome exhibited cellulases and hemicellulases with higher activity at 60 °C. It catalysed depolymerization of chemical pretreated rice straw as revealed by scanning electron microscopy and saccharification yield of 460 mg g −1 rice straw. Microbial diversity of RSV was distinct from other compost habitats, with predominance of members of phyla Firmicutes, Proteobacteria and Bacteroidetes; and Pseudoclostridium , Thermoanaerobacterium , Chelatococcus and Algoriphagus being most abundant genera. RSV harboured 1389 CAZyme encoding ORFs of glycoside hydrolase, carbohydrate esterase, glycosyl transferase, carbohydrate binding module and auxiliary activity functions. Microorganisms of Firmicutes showed central role in lignocellulose deconstruction with importance in hemicellulose degradation; whereas representatives of Proteobacteria and Bacteroidetes contributed to cellulose and lignin degradation, respectively. RSV consortium could be a resource for mining thermotolerant cellulolytic bacteria or enzymes and studying their synergism in deconstruction of chemically pretreated rice straw.

The objective of this study was to investigate how the relationships between bacterial communities and organic C (SOC) in topsoil (0–5 cm) are affected by tillage practices [conventional intensive tillage (CT) or no-tillage (NT)] and straw-returning methods [crop straw returning (S) or removal (NS)] under a rice-wheat rotation in central China. Soil bacterial communities were determined by high-throughput sequencing technology. After two cycles of annual rice-wheat rotation, compared with CT treatments, NT treatments generally had significantly more bacterial genera and monounsaturated fatty acids/saturated fatty acids (MUFA/STFA), but a decreased gram-positive bacteria/gram-negative bacteria ratio (G + /G − ). S treatments had significantly more bacterial genera and MUFA/STFA, but had decreased G + /G − compared with NS treatments. Multivariate analysis revealed that Gemmatimonas , Rudaea , Spingomonas , Pseudomonas , Dyella , Burkholderia , Clostridium , Pseudolabrys , Arcicella and Bacillus were correlated with SOC, and cellulolytic bacteria ( Burkholderia, Pseudomonas, Clostridium, Rudaea and Bacillus ) and Gemmationas explained 55.3% and 12.4% of the variance in SOC, respectively. Structural equation modeling further indicated that tillage and residue managements affected SOC directly and indirectly through these cellulolytic bacteria and Gemmationas . Our results suggest that Burkholderia, Pseudomonas, Clostridium, Rudaea , Bacillus and Gemmationas help to regulate SOC sequestration in topsoil under tillage and residue systems.

Little is known about the bacterial diversity of landfills and how environmental factors impact the diversity. In this study, PCR-based 454 pyrosequencing was used to investigate the bacterial communities of ten landfill leachate samples from five landfill sites in China. A total of 137 K useable sequences from the V3-V6 regions of the 16S rRNA gene were retrieved from 205 K reads. These sequences revealed the presence of a large number of operational taxonomic units (OTUs) in the landfills (709–1599 OTUs per sample). The most predominant bacterial representatives in the landfills investigated, regardless of geographic area, included Gammaproteobacteria , Firmicutes , and Bacteroidetes . The phyla Fusobacteria and Tenericutes were also found for the first time to be predominant in the landfills. The phylum Fusobacteria predominated (51.5 and 48.8 %) in two semi-arid landfills, and the phylum Tenericutes dominated (30.6 %) at one humid, subtropical landfill. Further, a large number of Pseudomonas was detected in most samples, comprising the dominant group and accounting for 40.9 to 92.4 % of the total abundance. Principal component analysis (PCA) and cluster analysis based on OTU abundance showed that the abundant taxa separated the bacterial community. Canonical correlation analysis (CCA) suggested that precipitation and landfilling age significantly impact on the bacterial community structure. The bacterial community function (e.g., cellulolytic bacteria, sulfate-reducing bacteria (SRB), sulfate-oxidizing bacteria, and xenobiotic organic compound (XOC)-degrading bacteria) was also diverse, but the pattern is unclear.