Isolation, screening and characterization of efficient cellulose-degrading fungal and bacterial strains and preparation of their consortium under in vitro studies.

In this investigation, cellulose-degrading fungi and bacteria were isolated from different partially decomposed cellulose-rich substrates, such as groundnut residues, rice straw, and rotten wood, following dilution plating techniques on carboxymethyl cellulose agar media and screening for potential cellulose degradation ability. The development of a clear halo zone surrounding the microbial colonies during the initial screening process using the Congo red test (20 isolates) suggested cellulose hydrolysis, and the highest cellulase production activity was implied by the isolates with the largest clear zone ratio (9 isolates). Using both macroscopic and microscopic examinations, as well as standard biochemical tests outlined in Bergey's Manual of Determinative Bacteriology, the genus-level identification of fungi and bacteria was accomplished. In order to molecularly identify the 4 isolated fungal and bacterial strains at the species level after being ultimately selected for cellulase production potential under in vitro studies, fungal and bacterial DNA was extracted and amplified by PCR using the universal primers ITS1 and ITS4 for fungi (ITS rRNA, 5.8S rRNA) and 8F and 1492R for bacterial isolates (16S rRNA). After sequencing, the PCR results were compared to other comparable sequences in GenBank (NCBI). Based on the available NCBI data, phylogenetic analysis of their ribosomal gene partial sequences revealed that DAJ2 (PP086700) shares 100% homology with Aspergillus foetidus, DTJ4 (PP086699) shares 99.74% similarity with Trichoderma atrobrunnium, DBJ6 (PP082584) shares 100% identity with Priestia megaterium, and DMB9 (PP082585) shares 99.88% homology with Micrococcus yunnanensis. The cellulolytic potential of Phanerochaete chrysosporium is well established. Therefore, it was considered a standard culture for comparison and was collected from the MTCC, Chandigarh, India. Overall, all 4 selected isolates and the check organism were mutually compatible or synergistic with each other, and their consortium is useful for the accelerated decomposition of organic constituents during rapid composting.

Cellulolytic potential of mangrove bacteria Bacillus haynesii DS7010 and the effect of anthropogenic and environmental stressors on bacterial survivability and cellulose metabolism.

Cellulose degrading bacterial diversity of Bhitarkanika mangrove ecosystem, India, was uncovered and the cellulose degradation mechanism in Bacillus haynesii DS7010 under the modifiers such as pH (pCO2), salinity and lead (Pb) was elucidated in the present study. The abundance of cellulose degrading heterotrophic bacteria was found to be higher in mangrove sediment than in water. The most potential strain, B. haynesii DS7010 showed the presence of endoglucanase, exoglucanase and ß-glucosidase with the maximum degradation recorded at 48 h of incubation, with 1% substrate concentration at 41 °C incubation temperature. Two glycoside hydrolase genes, celA and celB were confirmed in this bacterium. 3D structure prediction of the translated CelA and CelB proteins showed maximum similarities with glycoside hydrolase 48 (GH48) and glycoside hydrolase 5 (GH5) respectively. Native PAGE followed by zymogram assay unveiled the presence of eight isoforms of cellulase ranged from 78 kDa to 245 kDa. Among the stressors, most adverse effect was observed under Pb stress at 1400 ppm concentration, followed by pH at pH 4. This was indicated by prolonged lag phase growth, higher reactive oxygen species (ROS) production, lower enzyme activity and downregulation of celA and celB gene expressions. Salinity augmented bacterial metabolism up to 3% NaCl concentration. Mangrove leaf litter degradation by B. haynesii DS7010 indicated a substantial reduction in cellulolytic potential of the bacterium in response to the synergistic effect of the stressors. Microcosm set up with the stressors exhibited 0.97% decrease in total carbon (C%) and 0.02% increase in total nitrogen (N%) after 35 d of degradation while under natural conditions, the reduction in C and the increase in N were 4.05% and 0.2%, respectively. The findings of the study suggest the cellulose degradation mechanism of a mangrove bacterium and its resilience to the future consequences of environmental pollution and climate change.

The Isolation and Characterization of a Novel Psychrotolerant Cellulolytic Bacterium, Microbacterium sp. QXD-8T.

Cellulolytic microorganisms play a crucial role in agricultural waste disposal. Strain QXD-8T was isolated from soil in northern China. Similarity analyses of the 16S rRNA gene, as well as the 120 conserved genes in the whole-genome sequence, indicate that it represents a novel species within the genus Microbacterium. The Microbacterium sp. QXD-8T was able to grow on the CAM plate with sodium carboxymethyl cellulose as a carbon source at 15 °C, forming a transparent hydrolysis circle after Congo red staining, even though the optimal temperature for the growth and cellulose degradation of strain QXD-8T was 28 °C. In the liquid medium, it effectively degraded cellulose and produced reducing sugars. Functional annotation revealed the presence of encoding genes for the GH5, GH6, and GH10 enzyme families with endoglucanase activity, as well as the GH1, GH3, GH39, and GH116 enzyme families with ß-glucosidase activity. Additionally, two proteins in the GH6 family, one in the GH10, and two of nine proteins in the GH3 were predicted to contain a signal peptide and transmembrane region, suggesting their potential for extracellularly degrade cellulose. Based on the physiological features of the type strain QXD-8T, we propose the name Microbacterium psychrotolerans for this novel species. This study expands the diversity of psychrotolerant cellulolytic bacteria and provides a potential microbial resource for straw returning in high-latitude areas at low temperatures.

Enzymatic degradation of cellulose in soil: A review.

Cellulose degradation is a critical process in soil ecosystems, playing a vital role in nutrient cycling and organic matter decomposition. Enzymatic degradation of cellulosic biomass is the most sustainable and green method of producing liquid biofuel. It has gained intensive research interest with future perspective as the majority of terrestrial lignocellulose biomass has a great potential to be used as a source of bioenergy. However, the recalcitrant nature of lignocellulose limits its use as a source of energy. Noteworthy enough, enzymatic conversion of cellulose biomass could be a leading future technology. Fungal enzymes play a central role in cellulose degradation. Our understanding of fungal cellulases has substantially redirected in the past few years with the discovery of a new class of enzymes and Cellulosome. Efforts have been made from time to time to develop an economically viable method of cellulose degradation. This review provides insights into the current state of knowledge regarding cellulose degradation in soil and identifies areas where further research is needed.

Isolation and characterization of intestinal bacteria associated with cellulose degradation in grasshoppers (Orthoptera).

Insect gut bacteria play an essential role in the nutritional metabolism, growth, and development of insects. Grasshoppers (Orthoptera) are cellulose-rich plant-feeding pests. Although the biological potential of grasshopper gut microorganisms to assist cellulose decomposition is well established, microbial resources for efficient degradation of cellulose biomass are still scarce and need to be developed. In this study, we used selective media to isolate cellulose-degrading bacteria from the intestines of Atractomorpha sinensis, Trilophidia annulata, Sphingonotus mongolicus, and Calliptamus abbreviatus. Phylogenetic analysis based on the maximum likelihood method using 16S rDNA sequencing sequences to identify bacteria revealed the isolation of 11 strains belonging to 3 genera, including Klebsiella, Aeromonas, and Bacillus. The degradability of the isolates to cellulose was then determined by the DNS colorimetric method, and the results showed that Bacillus had the highest degradation rate. The elucidation of microbial cellulose degradation capacity in grasshoppers not only contributes to the understanding of multiple plant-insect-microbe interactions, but also provides a valuable microbial resource for solving the biomass conversion of cellulose species problem.

Gut microbial communities and their potential roles in cellulose digestion and thermal adaptation of earthworms.

Adaptations to temperature and food resources, which can be affected by gut microbiota, are two main adaptive strategies allowing soil fauna to survive in their habitats, especially for cold-blooded animals. Earthworms are often referred to as ecosystem engineers because they make up the biggest component of the animal biomass found in the soil. They are considered as an important indicator in the triangle of soil quality, health and functions. However, the roles of gut microbiota in the environmental adaptation of earthworms at a large scale remain obscure. We explored the gut bacterial communities and their functions in the environmental adaptation of two widespread earthworm species (Eisenia nordenskioldi Eisen and Drawida ghilarovi Gates) in Northeast China (1661 km). Based on our findings, the alpha diversity of gut bacterial communities decreased with the increase of latitude, and the gut bacterial community composition was shaped by both mean annual temperature (MAT) and cellulose. Actinobacteria, Proteobacteria, Firmicutes, and Planctomycetes, recognized as the predominant cellulose degraders, were keystone taxa driving gut bacterial interactions. Actinobacteria, Firmicutes, and Planctomycetes were influenced by MAT and cellulose, and had higher contributions to gut total cellulase activity. The optimal temperature for total cellulase in the gut of E. nordenskioldi (25-30 °C) was lower than that of D ghilarovi (40 °C). The gut microbiota-deleted earthworms had the lowest cellulose degradation rate (1.07 %). The cellulose was degraded faster by gut bacteria from the host they were derived, indicating the presence of home field advantage of cellulose decomposition. This study provides a foundation for understanding the biotic strategies adopted by earthworms when they enter a new habitat, with gut microbiota being central to food digestion and environmental adaptability.

The cell functions of phospholipase C-1, Ca2+/H+ exchanger-1, and secretory phospholipase A2 in tolerance to stress conditions and cellulose degradation in Neurospora crassa.

We investigated the cell functions of the Ca2+ signaling genes phospholipase C-1 (plc-1), Ca2+/H+ exchanger (cpe-1), and secretory phospholipase A2 (splA2) for stress responses and cellulose utilization in Neurospora crassa. The Δplc-1, Δcpe-1, and ΔsplA2 mutants displayed increased sensitivity to the alkaline pH and reduced survival during induced thermotolerance. The ΔsplA2 mutant also exhibited hypersensitivity to the DTT-induced endoplasmic reticulum (ER) stress, increased microcrystalline cellulose utilization, increased protein secretion, and glucose accumulation in the culture supernatants. Moreover, the ΔsplA2 mutant could not grow on microcrystalline cellulose during ER stress. Furthermore, plc-1, cpe-1, and splA2 synthetically regulate the acquisition of thermotolerance induced by heat shock, responses to alkaline pH and ER stress, and utilization of cellulose and other alternate carbon sources in N. crassa. In addition, expression of the alkaline pH regulator, pac-3, and heat shock proteins, hsp60, and hsp80 was reduced in the Δplc-1, Δcpe-1, and ΔsplA2 single and double mutants. The expression of the unfolded protein response (UPR) markers grp-78 and pdi-1 was also significantly reduced in the mutants showing growth defect during ER stress. The increased cellulolytic activities of the ΔsplA2 and Δcpe-1; ΔsplA2 mutants were due to increased cbh-1, cbh-2, and endo-2 expression in N. crassa. Therefore, plc-1, cpe-1, and splA2 are involved in stress responses and cellulose utilization in N. crassa.

Insights into the H2O2-Driven Lytic Polysaccharide Monooxygenase Activity on Efficient Cellulose Degradation in the White Rot Fungus Irpex lacteus.

In contrast to O2, H2O2 as the cosubstrate for lytic polysaccharide monooxygenases (LPMOs) exhibits great advantages in industrial settings for cellulose degradation. However, H2O2-driven LPMO reactions from natural microorganisms have not been fully explored and understood. Herein, secretome analysis unraveled the H2O2-driven LPMO reaction in the efficient lignocellulose-degrading fungus Irpex lacteus, including LPMOs with different oxidative regioselectivities and various H2O2-generating oxidases. Biochemical characterization of H2O2-driven LPMO catalysis showed orders of magnitude improvement in catalytic efficiency compared to that of O2-driven LPMO catalysis for cellulose degradation. Significantly, H2O2 tolerance of LPMO catalysis in I. lacteus was an order of magnitude higher than that in other filamentous fungi. In addition, natural reductants, gallic acid, in particular, presented in lignocellulosic biomass could sufficiently maintain LPMO catalytic reactions. Moreover, the H2O2-driven LPMO catalysis exhibited synergy with canonical endoglucanases for efficient cellulose degradation. Taken together, these findings demonstrate the great application potential of the H2O2-driven LPMO catalysis for upgrading cellulase cocktails to further improve cellulose degradation efficiency.

Marinagarivorans cellulosilyticus sp. nov., a cellulolytic bacterium isolated from the deep-sea off Noma-misaki, Japan.

Cells from strain GE09T, isolated from an artificially immersed nanofibrous cellulose plate in the deep sea, were Gram-stain-negative, motile, aerobic cells that could grow with cellulose as their only nutrient. Strain GE09T was placed among members of Cellvibrionaceae, in the Gammaproteobacteria, with Marinagarivorans algicola Z1T, a marine degrader of agar, as the closest relative (97.4 % similarity). The average nucleotide identity and digital DNA-DNA hybridization values between GE09T and M. algicola Z1T were 72.5 and 21.2 %, respectively. Strain GE09T degraded cellulose, xylan and pectin, but not starch, chitin and agar. The different carbohydrate-active enzymes encoded in the genomes of strain GE09T and M. algicola Z1T highlights their differences in terms of target energy sources and reflects their isolation environments. The major cellular fatty acids of strain GE09T were C18 : 1 ω7c, C16 : 0 and C16 : 1 ω7c. The polar lipid profile showed phosphatidylglycerol and phosphatidylethanolamine. The major respiratory quinone was Q-8. Based on these distinct taxonomic characteristics, strain GE09T represents a new species in the genus Marinagarivorans, for which we propose the name Marinagarivorans cellulosilyticus sp. nov. (type strain GE09T=DSM 113420T=JCM 35003T).

Target integration of an exogenous ß-glucosidase enhances cellulose degradation and ethanol production in Clostridium cellulolyticum.

The bacteria Clostridium cellulolyticum is a promising candidate for consolidated bioprocessing (CBP). However, genetic engineering is necessary to improve this organism's cellulose degradation and bioconversion efficiencies to meet standard industrial requirements. In this study, CRISPR-Cas9n was used to integrate an efficient ß-glucosidase into the genome of C. cellulolyticum, disrupting lactate dehydrogenase (ldh) expression and reducing lactate production. The engineered strain showed a 7.4-fold increase in ß-glucosidase activity, a 70% decrease in ldh expression, a 12% increase in cellulose degradation, and a 32% increase in ethanol production compared to wild type. Additionally, ldh was identified as a potential site for heterologous expression. These results demonstrate that simultaneous ß-glucosidase integration and lactate dehydrogenase disruption is an effective strategy for increasing cellulose to ethanol bioconversion rates in C. cellulolyticum.

Bacterial composition along the digestive tract of the Horned Screamer (Anhima cornuta), a tropical herbivorous bird.

Background: The Horned Screamer (Anhima cornuta) is an herbivorous bird that inhabits wetlands of the South American tropical region. We hypothesize that due to its herbivorous niche, its digestive tract compartments may have bacteria specialized in fermenting complex plant carbohydrates. To test this hypothesis, we compared the bacterial communities along the gastrointestinal tract (GIT) of a Horned Screamer captured in Venezuela. Methods: Samples were taken from tissues and content of the proventriculus and the small intestine (considered for this study as upper GIT), and the large intestine and cecum (lower GIT). The bacterial community was characterized by sequencing the V4 region of the 16S rRNA gene. Bioinformatic analysis was performed using QIIME, QIITA and Microbiome Analyst. The association between microbial taxonomy and function was analyzed using their Greengenes OTU IDs and a custom KEGG BRITE hierarchical tree and visualized with BURRITO. Results: The Screamer's gastrointestinal microbiota was composed by seven phyla being Firmicutes and Bacteroidetes the most predominant. The dominant taxa in the upper GIT were Helicobacter, Vibrio, Enterobacter, Acinetobacter and Staphylococcus. The dominant taxa in the lower GIT were Oribacterium, Blautia, Roseburia, Ruminococcus, Desulfovibrio, Intestinimonas, Marvinbryantia and Parabacteroides. Complete degradation of cellulose to the end-products acetate, propanoate, butanoate and acetoacetate was found in the upper and lower GIT without significant differences. Conclusion: Our study confirmed changes in bacterial community composition throughout the GIT of the Horned Screamer primarily associated with the production of metabolic end-products of carbohydrate digestion essential for the fermentation of the herbivorous diet.

Exploration of ß-glucosidase-producing microorganisms community structure and key communities driving cellulose degradation during composting of pure corn straw by multi-interaction analysis.

Poor management of crop residues leads to environmental pollution and composting is a sustainable practice for addressing the challenge. However, knowledge about composting with pure crop straw is still limited, which is a novel and feasible composting strategy. In this study, pure corn straw was in-situ composted for better management. Community structure of ß-glucosidase-producing microorganisms during composting was deciphered using high-throughput sequencing. Results showed that the compost was mature with organic matter content of 37.83% and pH value of 7.36 and pure corn straw could be composted successfully. Cooling phase was major period for cellulose degradation with the highest ß-glucosidase activity (476.25 µmol·p-Nitr/kg·dw·min) and microbial diversity (Shannon index, 3.63; Chao1 index, 500.81). Significant compositional succession was observed in the functional communities during composting with Streptomyces (14.32%), Trichoderma (13.85%) and Agromyces (11.68%) as dominant genera. ß-Glucosidase-producing bacteria and fungi worked synergistically as a network to degrade cellulose with Streptomyces (0.3045**) as the key community revealed by multi-interaction analysis. Organic matter (-0.415***) and temperature (-0.327***) were key environmental parameters regulating cellulose degradation via influencing ß-glucosidase-producing communities, and ß-glucosidase played a key role in mediating this process. The above results indicated that responses of ß-glucosidase-producing microorganisms to cellulose degradation were reflected at both network and individual levels and multi-interaction analysis could better explain the relationship between variables concerning composting cellulose degradation. The work is of significance for understanding cellulose degradation microbial communities and process during composting of pure corn straw.

Transcription factor FfMYB15 regulates the expression of cellulase gene FfCEL6B during mycelial growth of Flammulina filiformis.

BACKGROUND: Cellulose degradation can determine mycelial growth rate and affect yield during the growth of Flammulina filiformis. The degradation of cellulose requires the joint action of a variety of cellulases, and some cellulase-related genes have been detected in mushrooms. However, little is known about the transcriptional regulatory mechanisms of cellulose degradation. RESULTS: In this study, FfMYB15 that may regulate the expression of cellulase gene FfCEL6B in F. filiformis was identified. RNA interference (RNAi) showed that FfCEL6B positively regulated mycelial growth. Gene expression analyses indicated that the expression patterns of FfCEL6B and FfMYB15 in mycelia cultured on the 0.9% cellulose medium for different times were similar with a correlation coefficient of 0.953. Subcellular localization and transcriptional activity analyses implied that FfMYB15 was located in the nucleus and was a transcriptional activator. Electrophoretic mobility shift assay (EMSA) and dual-luciferase assays demonstrated that FfMYB15 could bind and activate FfCEL6B promoter by recognizing MYB cis-acting element. CONCLUSIONS: This study indicated that FfCEL6B played an active role in mycelial growth of F. filiformis and was regulated by FfMYB15.

Glycosyltransferase-Related Protein GtrA Is Essential for Localization of Type IX Secretion System Cargo Protein Cellulase Cel9A and Affects Cellulose Degradation in Cytophaga hutchinsonii.

The Gram-negative bacterium Cytophaga hutchinsonii digests cellulose through a novel cellulose degradation mechanism. It possesses the lately characterized type IX secretion system (T9SS). We recently discovered that N-glycosylation of the C-terminal domain (CTD) of a hypothetical T9SS substrate protein in the periplasmic space of C. hutchinsonii affects protein secretion and localization. In this study, green fluorescent protein (GFP)-CTDCel9A recombinant protein was found with increased molecular weight in the periplasm of C. hutchinsonii. Site-directed mutagenesis studies on the CTD of cellulase Cel9A demonstrated that asparagine residue 900 in the D-X-N-X-S motif is important for the processing of the recombinant protein. We found that the glycosyltransferase-related protein GtrA (CHU_0012) located in the cytoplasm of C. hutchinsonii is essential for outer membrane localization of the recombinant protein. The deletion of gtrA decreased the abundance of the outer membrane proteins and affected cellulose degradation by C. hutchinsonii. This study provided a link between the glycosylation system and cellulose degradation in C. hutchinsonii. IMPORTANCE N-Glycosylation systems are generally limited to some pathogenic bacteria in prokaryotes. The disruption of the N-glycosylation pathway is related to adherence, invasion, colonization, and other phenotypic characteristics. We recently found that the cellulolytic bacterium Cytophaga hutchinsonii also has an N-glycosylation system. The cellulose degradation mechanism of C. hutchinsonii is novel and mysterious; cellulases and other proteins on the cell surface are involved in utilizing cellulose. In this study, we identified an asparagine residue in the C-terminal domain of cellulase Cel9A that is necessary for the processing of the T9SS cargo protein. Moreover, the glycosyltransferase-related protein GtrA is essential for the localization of the GFP-CTDCel9A recombinant protein. Deletion of gtrA affected cellulose degradation and the abundance of outer membrane proteins. This study enriched the understanding of the N-glycosylation system in C. hutchinsonii and provided a link between N-glycosylation and cellulose degradation, which also expanded the role of the N-glycosylation system in bacteria.

Deciphering microbial syntrophic mechanisms for simultaneous removal of nitrate and Cr(VI) by Mn@Corn cob immobilized bioreactor: Performance, enhancement mechanisms and community assembly.

When bioremediation is applied to Cr(VI) and NO3--N contaminated groundwater, the lack of carbon sources and weak physiological activity dramatically affect the treatment efficacy. Hence, a bioreactor consisting of cellulose degradation-manganese (Mn) cycling bilayer carrier and two core strains was established. After 270 operating days, the experimental group (EG) achieved 96.34 and 95.37% of NO3--N and Cr(VI) removal efficiency, respectively. When the C/N ratio was reduced to 1.0, cellulose-degrading strain CDZ9 produced significantly hydrolyzed cellulose from the corn cob substrate. Meanwhile, the balance between microbial metabolic activity and carbon supply was manipulated by the dissimilatory Mn-reducing strain MFG10. Dissolved organic matter response in EG provided evidence for enhanced carbon utilization and electron transfer processes. The syntrophic relationship between EG core strains significantly enhanced bioreactor metabolism and bioactivity. It drove the coupling of different elemental cycles with contaminant removal including carbon metabolism, nitrogen metabolism, Mn cycle and Cr(VI) reduction.

Deciphering the efficient cellulose degradation by the thermophilic fungus Myceliophthora thermophila focused on the synergistic action of glycoside hydrolases and lytic polysaccharide monooxygenases.

The thermophilic fungus Myceliophthora thermophila as an efficient decomposer secretes various glycoside hydrolases and auxiliary oxidation enzymes to deconstruct cellulose. However, the core enzymes critical for efficient cellulose degradation and their interactions with other cellulolytic enzymes remain unclear. Herein, the transcriptomic analysis of M. thermophila grown on Avicel exhibited that cellulases from GH5_5, GH6 and GH7, and lytic polysaccharide monooxygenases (LPMOs) from AA9 contributed to cellulose degradation. Moreover, the peptide mass fingerprinting analysis of major extracellular proteins and corresponding gene-knockout strains studies revealed that MtCel7A and MtCel5A were the core cellulolytic enzymes. Furthermore, synergistic experiments found that hydrolytic efficiencies of MtCel7A and MtCel5A were both improved by mixture C1/C4 oxidizing MtLPMO9H, but inhibited by C1 oxidizing MtLPMO9E and C4 oxidizing MtLPMO9J respectively. These results demonstrated the potential application of C1/C4 oxidizing LPMOs for future designing novel cellulolytic enzyme cocktails on the efficient conversion of cellulose into biofuels and biochemicals.

Sorption of Cellulases in Biofilm Enhances Cellulose Degradation by Bacillus subtilis.

Biofilm commonly forms on the surfaces of cellulosic biomass but its roles in cellulose degradation remain largely unexplored. We used Bacillus subtilis to study possible mechanisms and the contributions of two major biofilm components, extracellular polysaccharides (EPS) and TasA protein, to submerged biofilm formation on cellulose and its degradation. We found that biofilm produced by B. subtilis is able to absorb exogenous cellulase added to the culture medium and also retain self-produced cellulase within the biofilm matrix. The bacteria that produced more biofilm degraded more cellulose compared to strains that produced less biofilm. Knockout strains that lacked both EPS and TasA formed a smaller amount of submerged biofilm on cellulose than the wild-type strain and also degraded less cellulose. Imaging of biofilm on cellulose suggests that bacteria, cellulose, and cellulases form cellulolytic biofilm complexes that facilitate synergistic cellulose degradation. This study brings additional insight into the important functions of biofilm in cellulose degradation and could potentiate the development of biofilm-based technology to enhance biomass degradation for biofuel production.

Chemical Characterization and Visualization of Progressive Brown Rot Decay of Wood by Near Infrared Imaging and Multivariate Analysis.

Brown rot fungi cause a type of wood decay characterized by carbohydrate degradation and lignin modification. The chemical and physical changes caused by brown rot are usually studied using bulk analytical methods, but these methods fail to consider local variations within the wood material. In this study we applied hyperspectral near infrared imaging to Scots pine sapwood samples exposed to the brown rot fungi Coniophora puteana and Rhodonia placenta to obtain position-resolved chemical information on the fungal degradative process. A stacked-sample decay test was used to create a succession of decay stages within the samples. The results showed that the key chemical changes associated with decay were the degradation of amorphous and crystalline carbohydrates and an increase in aromatic and carbonyl functionality in lignin. The position-resolved spectral data revealed that the fungi initiated degradation in earlywood, and that earlywood remained more extensively degraded than latewood even in advanced decay stages. Apart from differences in mass losses, the two fungi produced similar spectral changes in a similar spatial pattern. The results show that near infrared imaging is a useful tool for analyzing brown rot decayed wood and may be used to advance our understanding of fungal degradative processes.

Complete genome sequencing and investigation on the fiber-degrading potential of Bacillus amyloliquefaciens strain TL106 from the tibetan pig.

BACKGROUND: Cellulolytic microorganisms are considered a key player in the degradation of feed fiber. These microorganisms can be isolated from various resources, such as animal gut, plant surfaces, soil and oceans. A new strain of Bacillus amyloliquefaciens, TL106, was isolated from faeces of a healthy Tibetan pigs. This strain can produce cellulase and shows strong antimicrobial activity in mice. Thus, in this study, to better understand the strain of B. amyloliquefaciens TL106 on degradation of cellulose, the genome of the strain TL106 was completely sequenced and analyzed. In addition, we also explored the cellulose degradation ability of strain TL106 in vitro. RESULTS: TL106 was completely sequenced with the third generation high-throughput DNA sequencing. In vitro analysis with enzymatic hydrolysis identified the activity of cellulose degradation. TL106 consisted of one circular chromosome with 3,980,960 bp and one plasmid with 16,916 bp, the genome total length was 3.99 Mb and total of 4,130 genes were predicted. Several genes of cellulases and hemicellulase were blasted in Genbank, including ß-glucosidase, endoglucanase, ß-glucanase and xylanase genes. Additionally, the activities of amylase (20.25 U/mL), cellulase (20.86 U/mL), xylanase (39.71 U/mL) and ß-glucanase (36.13 U/mL) in the fermentation supernatant of strain TL106 were higher. In the study of degradation characteristics, we found that strain TL106 had a better degradation effect on crude fiber, neutral detergent fiber, acid detergent fiber, starch, arabinoxylan and ß-glucan of wheat and highland barley . CONCLUSIONS: The genome of B. amyloliquefaciens TL106 contained several genes of cellulases and hemicellulases, can produce carbohydrate-active enzymes, amylase, cellulase, xylanase and ß-glucanase. The supernatant of fermented had activities of strain TL106. It could degrade the fiber fraction and non-starch polysaccharides (arabinoxylans and ß-glucan) of wheat and highland barley. The present study demonstrated that the degradation activity of TL106 to crude fiber which can potentially be applied as a feed additive to potentiate the digestion of plant feed by monogastric animals.

Biological denitrification potential of cellulase-producing Cupriavidus sp. ZY7 and denitrifying Aquabacterium sp. XL4 at low carbon-to-nitrogen ratio: Performance and synergistic properties.

This study emphasizes on the cellulase production characteristics of strain ZY7 and its collaboration with nitrate-dependent ferrous oxidizing (NFO) strain XL4 to achieve efficient denitrification at low carbon-to-nitrogen (C/N) ratio. Results indicated that the denitrification efficiency increased from 65.47 to 97.99% at 24 h after co-culture at C/N of 1.0. Three-dimensional fluorescence excitation-emission matrix (3D-EEM) showed significant changes in the intensity of soluble microbial products (SMP), fulvic-like materials, and aromatic proteins after co-culture. Bio-precipitates were characterized by Scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR), and X-ray diffraction (XRD), which showed that cellulose structure was disrupted and the metabolites were potential carbon source for denitrification. In addition, cellulase activity suggested that the hydrolysis of ß-1,4-glycosidic bonds and oligosaccharides may be the rate-limiting steps in cellulose degradation. This work promoted the understanding of denitrification characteristics of co-culture and expanded the application of cellulose degrading bacteria in sewage treatment.