Bo Xu

Bio: Bo Xu is an academic researcher. The author has contributed to research in topics: Cellulase & Keratinase. The author has an hindex of 3, co-authored 3 publications receiving 54 citations.

Isolation and characterization of a new keratinolytic bacterium that exhibits significant feather-degrading capability

Abstract: A novel bacterium, Bacillus licheniformis K-19, which produces a large amount of akeratinase that is extremely thermostable and has a broad resistance to pH, was isolated and characterized. The maximum amount of keratinase activity (about 224 Uml-1) was produced at 37°C when the bacterium was cultured for 72 h in broth containing feather meal with initial pH of 7.5. The keratinase activity was observed over a wide range of temperatures (30 - 90°C) and pH values (pH 6 - 10). It was optimal at 60°C and pH 7.5 - 8 respectively. These results suggest potential biotechnological applications of this bacterium that involve hydrolysis of keratin, including the improvement of the nutritional properties of feathers (and other keratins) used as supplementary feedstuffs. Key words: Bacillus licheniformis, chicken feather, keratin, keratinolytic protease.

Study of fecal bacterial diversity in Yunnan snub-nosed monkey (Rhinopithecus bieti) using phylogenetic analysis of cloned 16S rRNA gene sequences

Abstract: The bacterial diversity in fecal samples from Yunnan snub-nosed monkey ( Rhinopithecus bieti ) was investigated by constructed 16S rRNA gene clone library and restriction fragment length polymorphism analysis. As a result, a total of 156 representative clones for each profile, comprising nearly full length sequences (with a mean length of 1.5 kb) were sequenced and submitted to an on-line similarity search and neighbor-joining phylogenetic analysis. Using the criterion of 97%, these 16S rRNA gene sequences were binned in 129 OTUs. 11 sequences whose similarity is 97% were affiliated to the cultured bacteria and accounted for 7.05% of the total clones. For 23 sequences (14.74%), the similarity with the database was in the range of 89 - 97%. The remaining 122 sequences (78.21%) were uncultured and unidentified bacteria. Based on the phylogenetic analysis, the fecal bacteria of R. bieti distributed mainly in 6 bacteriophyta of Firmicutes, Proteobacteria, Bacteroidetes, Fibrobacteres, Spirochaetes and Actinobacteria , and belonged to 17 genera. Besides, there were a large number of uncultured and unidentified bacteria. These results illustrate the fecal bacteria diversity of R. bieti. Key Words : Rhinopithecus bieti, fecal bacterial diversity, 16S rRNA gene, phylogenetic analysis.

Transcriptome analysis of Termitomyces albuminosus reveals the biodegradation of lignocellulose

Abstract: OBJECTIVE To study whether Termitomyces albuminosus can degrade lignocelluloses and to understand the symbiotic relationship between termite mushroom and fungus-growing termite. METHODS cDNA library of T. albuminosus was sequenced by the Roche 454 GS FLX Titanium platform, and the diverse enzymes relevant to degradation of cellulose and lignin of symbiotic fungus T. albuminosus were analyzed. RESULTS Eighth sequencing run resulted in a total of 82386 reads (express sequence tags, EST). After removing the vector and primer sequences, the remained 54410 reads were assembled into 3301 contigs and 3193 singletons. Comparing sequence similarity with known proteins, these sequences, representing approximately 2681 unique genes, were successfully annotated using BLAST searches (E-value < or = 1e(-10)) against the Nr, SwissProt and CDD databases. The T. albuminosus transcripts included 33 enzymes putatively involved in cellulose and hemicelluloses biodegradation. 5 enzymes could hydrolyze cellulose and others had catalytic activities for degradation of hemicelluloses, starch and glycogen and chitin. Moreover, four genes encoding laccases and a single aryl-alcohol oxidase which could degrade lignin were also identified. These results revealed symbiosis fungus T. albuminosus had many laccases and possibly decomposed phenolic compounds from plant litter. CONCLUSIONS Data presented in this study indicated that T. albuminosus had the ability to degrade lignin, which made cellulose more easily degraded by the cellulase produced by fungus-growing termite.

The Fibrobacteres : an Important Phylum of Cellulose-Degrading Bacteria

Abstract: The phylum Fibrobacteres currently comprises one formal genus, Fibrobacter, and two cultured species, Fibrobacter succinogenes and Fibrobacter intestinalis, that are recognised as major bacterial degraders of lignocellulosic material in the herbivore gut. Historically, members of the genus Fibrobacter were thought to only occupy mammalian intestinal tracts. However, recent 16S rRNA gene-targeted molecular approaches have demonstrated that novel centres of variation within the genus Fibrobacter are present in landfill sites and freshwater lakes, and their relative abundance suggests a potential role for fibrobacters in cellulose degradation beyond the herbivore gut. Furthermore, a novel subphylum within the Fibrobacteres has been detected in the gut of wood-feeding termites, and proteomic analyses have confirmed their involvement in cellulose hydrolysis. The genome sequence of F. succinogenes rumen strain S85 has recently suggested that within this group of organisms a "third" way of attacking the most abundant form of organic carbon in the biosphere, cellulose, has evolved. This observation not only has evolutionary significance, but the superior efficiency of anaerobic cellulose hydrolysis by Fibrobacter spp., in comparison to other cellulolytic rumen bacteria that typically utilise membrane-bound enzyme complexes (cellulosomes), may be explained by this novel cellulase system. There are few bacterial phyla with potential functional importance for which there is such a paucity of phenotypic and functional data. In this review, we highlight current knowledge of the Fibrobacteres phylum, its taxonomy, phylogeny, ecology and potential as a source of novel glycosyl hydrolases of biotechnological importance.

Complementary symbiont contributions to plant decomposition in a fungus-farming termite

Abstract: Termites normally rely on gut symbionts to decompose organic matter but the Macrotermitinae domesticated Termitomyces fungi to produce their own food. This transition was accompanied by a shift in the composition of the gut microbiota, but the complementary roles of these bacteria in the symbiosis have remained enigmatic. We obtained high-quality annotated draft genomes of the termite Macrotermes natalensis, its Termitomyces symbiont, and gut metagenomes from workers, soldiers, and a queen. We show that members from 111 of the 128 known glycoside hydrolase families are represented in the symbiosis, that Termitomyces has the genomic capacity to handle complex carbohydrates, and that worker gut microbes primarily contribute enzymes for final digestion of oligosaccharides. This apparent division of labor is consistent with the Macrotermes gut microbes being most important during the second passage of comb material through the termite gut, after a first gut passage where the crude plant substrate is inoculated with Termitomyces asexual spores so that initial fungal growth and polysaccharide decomposition can proceed with high efficiency. Complex conversion of biomass in termite mounds thus appears to be mainly accomplished by complementary cooperation between a domesticated fungal monoculture and a specialized bacterial community. In sharp contrast, the gut microbiota of the queen had highly reduced plant decomposition potential, suggesting that mature reproductives digest fungal material provided by workers rather than plant substrate.

Diet Versus Phylogeny: a Comparison of Gut Microbiota in Captive Colobine Monkey Species

Abstract: Both diet and host phylogeny shape the gut microbial community, and separating out the effects of these variables can be challenging. In this study, high-throughput sequencing was used to evaluate the impact of diet and phylogeny on the gut microbiota of nine colobine monkey species (N = 64 individuals). Colobines are leaf-eating monkeys that fare poorly in captivity-often exhibiting gastrointestinal (GI) problems. This study included eight Asian colobines (Rhinopithecus brelichi, Rhinopithecus roxellana, Rhinopithecus bieti, Pygathrix nemaeus, Nasalis larvatus, Trachypithecus francoisi, Trachypithecus auratus, and Trachypithecus vetulus) and one African colobine (Colobus guereza). Monkeys were housed at five different captive institutes: Panxi Wildlife Rescue Center (Guizhou, China), Beijing Zoo, Beijing Zoo Breeding Center, Singapore Zoo, and Singapore Zoo Primate Conservation Breeding Center. Captive diets varied widely between institutions, but within an institution, all colobine monkey species were fed nearly identical or identical diets. In addition, four monkey species were present at multiple captive institutes. This allowed us to parse the effects of diet and phylogeny in these captive colobines. Gut microbial communities clustered weakly by host species and strongly by diet, and overall, colobine phylogenetic relationships were not reflected in gut microbiota analyses. Core microbiota analyses also identified several key taxa-including microbes within the Ruminococcaceae and Lachnospiraceae families-that were shared by over 90% of the monkeys in this study. Microbial species within these families include many butyrate producers that are important for GI health. These results highlight the importance of diet in captive colobines.

Bacillus safensis LAU 13: a new source of keratinase and its multi-functional biocatalytic applications

Abstract: A newly isolated bacterium identified as Bacillus safensis based on biochemical tests and 16S rRNA analysis and its mutant variant created by exposure to ultraviolet radiation at 254 nm were investigated for keratinolytic activity. The wild-type strain produced 35.4–50.4 U/mL keratinase over a period of 120 h, while the mutant one yielded 64.4–108.5 U/mL keratinase for the same period of 120 h. The optimal conditions for the enzyme activities were pH 7.5 and 40 °C. The mutant and wild-type strain keratinases retained 59% and 54% of their activity after 12 h pretreatment at 40 °C, and 64% and 60% of their activity after 12 h at pH 7.5, respectively. The keratinases showed high substrate specificity for feathers, but low specificity for human and bovine hairs. The enzymes were activated by Na+, Ca2+, Fe2+ and Mg2+. However, while Mn2+ activated the enzyme from the mutant strain, it inhibited that of the wild type. The mutant and wild-type strain completely degraded whole chicken feathers after 6 and 9 days ...

ARTICLE; AGRICULTURE AND ENVIRONMENTAL BIOTECHNOLOGY Bacillus safensis LAU 13: a new source of keratinase and its multi-functional biocatalytic applications

Abstract: A newly isolated bacterium identified as Bacillus safensis based on biochemical tests and 16S rRNA analysis and its mutant variant created by exposure to ultraviolet radiation at 254 nm were investigated for keratinolytic activity. The wild-type strain produced 35.450.4 U/mL keratinase over a period of 120 h, while the mutant one yielded 64.4108.5 U/mL keratinase for the same period of 120 h. The optimal conditions for the enzyme activities were pH 7.5 and 40 C. The mutant and wild-type strain keratinases retained 59% and 54% of their activity after 12 h pretreatment at 40 C, and 64% and 60% of their activity after 12 h at pH 7.5, respectively. The keratinases showed high substrate specificity for feathers, but low specificity for human and bovine hairs. The enzymes were activated by Na C ,C a 2C ,F e 2C and Mg 2C . However, while Mn 2C activated the enzyme from the mutant strain, it inhibited that of the wild type. The mutant and wild-type strain completely degraded whole chicken feathers after 6 and 9 days at 30 § 2 C, and also completely dehaired goat skin within 12 and 16 h, respectively, without damage to the skin. Similarly, remarkable destaining of blood-stained cloth occurred within 23 h. The obtained results showed an improvement in the properties of the mutant strain for use of the microorganism or its enzyme as biocatalysts.