Characteristics of Extended-Spectrum ß-Lactamase-Producing Escherichia coli Derived from Food and Humans in Northern Xinjiang, China.

This study aimed to investigate the drug resistance, molecular characteristics, and genetic relationship of extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli isolated from food and human stool samples in northern Xinjiang. From 2015 to 2016, a total of 431 samples (meats and vegetables) were collected from retail markets and supermarkets located in the regions of Urumqi, Shihezi, and Kuitun in Xinjiang, China, and 20 human stool samples from the Shihezi Hospital. The PCR method was used to detect E. coli, and the presence of ESBL-producing E. coli was confirmed using the K-B disk diffusion confirmatory method. The susceptibility to ESBL-producing E. coli was tested by the microdilution broth method, and the minimum inhibitory concentration was determined. PCR was used to detect the resistance and virulence genes of ESBL-producing E. coli, and phylogenetics, plasmid replicon typing, screening of three integrons, and multilocus sequence typing (MLST) were performed. The results showed that 127 E. coli strains (15 human stool and 112 food samples) were isolated. Out of the 127 E. coli strains, 38 strains (6 human stool and 32 food 34 samples) of ESBL-producing E. coli were identified through screening. These 38 strains showed resistance to cefotaxime (94.74%) and cefepime (94.74%), and were sensitive to meropenem (0.00%). The most detected resistance genes were blaTEM (47.37%), and the most detected virulence genes were fimH (97.73%), ompA (97.73%), hlyE (97.73%), and crl (97.37%). The isolates belonged to phylogroups B1 (42.11%), C (23.68%), and A (21.05%). Among the plasmid replicon subtypes, IncFIB was the main type (42.11%). The integrons detected were of the first type (47.37%) and the third type (26.32%). The 38 E. coli strains had 19 different sequence-type (ST) strains. These 38 strains of ESBL-producing E. coli were analyzed using MLST and STs are varied.

Complete Genome Sequence Analysis of Acidithiobacillus ferrivorans XJFY6S-08 Reveals Environmental Adaptation to Alpine Acid Mine Drainage.

The present work reported the complete genome sequence analysis of Acidithiobacillus ferrivorans strain XJFY6S-08 isolated from acid mine drainage in Fuyun copper mine in Xinjiang, China, revealing the potential for extreme environmental adaptation. The strain XJFY6S-08 possesses 3,161,380 bp in length and 56.55% GC content. Genomic analysis revealed that this strain harbors metal-tolerant genes coding for the mer operon, arsRBC operon and a variety of metal assimilation and efflux proteins. Genes coding for K+/H+ transporting ATPase and the Na+/H+ antiporter gene nhaA for pH adaptation were identified. The presence of genes associated with various DNA repair enzymes and the synthesis of mycosporine-like amino acids precursor support the UVR resistance mechanisms. The genes related to membrane modifications (ppiBCD, slyD, surA, cfa and fabF) and resistance-nodulation-division (RND) family can play a crucial role in organic solvents tolerance. The strain XJFY6S-08 resists low-temperature conditions by a set of mechanisms such as changes of RNA metabolism, transmembrane transport, compatible solutes and transport, biofilm and EPS formation, chemotaxis and motility and ROS scavenging. These findings can provide important information for further studying the comparative genome and environmental adaptation mechanism of A. ferrivorans.

Evaluation of indigenous lactic acid bacteria of raw mare milk from pastoral areas in Xinjiang, China, for potential use in probiotic fermented dairy products.

In the present study 114 lactic acid bacteria strains, isolated from raw mare milks from pastoral areas for ethnic minorities in northwest China, were screened for probiotic traits, and their characteristics were compared with those of Lactobacillus rhamnosus GG, a commercial strain. Among the 114 strains identified, the most common species was Pediococcus pentosaceus (n = 52), followed by Leuconostoc lactis (n = 35), Lactobacillus helveticus (n = 7), Lactobacillus plantarum (n = 6), Lactobacillus kefiri (n = 5), Lactobacillus curvatus (n = 4), Lactobacillus paracasei (n = 3), and Lactococcus garvieae (n = 3). Based on acid and bile salt tolerance, 15 strains were further selected. All selected strains were subjected to a series of in vitro tests to assess their technological properties, including cell surface hydrophobicity (13.6-56.2%), autoaggregation ability (9.26-38.30%), coaggregation ability, and heat and lysozyme survival rates (84.74-94.01% and 80.52-99.37%, respectively). In vitro antagonism showed that Lb. plantarum (M5-19, M8-60, M8-59) exhibited the most strong inhibitory activity against 7 tested pathogens. Moreover, antibiotic resistance and hemolytic activity were investigated for safety assessment. No strain exhibited hemolytic activity, and most of the strains were sensitive to a series of 14 antibiotics of clinical importance. Ultimately, the principal component analysis of all data obtained above showed that 2 Lb. plantarum strains (M8-59, M8-60) and Lb. paracasei M1-36 exhibited the best potential for their inclusion as adjunct functional cultures in local fermented dairy products.

Genotyping and plant-derived glycan utilization analysis of Bifidobacterium strains from mother-infant pairs.

BACKGROUND: Bifidobacteria are important probiotics; some of the beneficial effects of bifidobacteria are achieved by the hydrolysis of glycans in the human gut. However, because the diet of breastfed infants typically lacks plant-derived glycans, in the gut environment of mothers and their breastfed infants, the mother will intake a variety of plant-derived glycans, such as from onions and bananas, through her diet. Under this assumption, we are interested in whether the same species of bifidobacteria isolated from mother-infant pairs present a distinction in their hydrolysis of plant-derived carbohydrates. RESULTS: Among the 36 Bifidobacterium strains, bifidobacterial carbohydrate utilization showed two trends related to the intestinal environment where the bacteria lived. Compared with infant-type bifidobacterial strains, adult-type bifidobacterial strains preferred to use plant-derived glycans. Of these strains, 10 isolates, 2 Bifidobacterium pseudocatenulatum (B. pseudocatenulatum), 2 Bifidobacterium pseudolongum (B. pseudolongum), 2 Bifidobacterium bifidum (B. bifidum), 2 Bifidobacterium breve (B. breve), and 2 Bifidobacterium longum (B. longum), were shared between the mother-infant pairs. Moreover, the repetitive sequence-based polymerase chain reaction (rep-PCR) results illustrated that B. pseudolongum and B. bifidum showed genotypic similarities of 95.3 and 98.2%, respectively. Combined with the carbohydrate fermentation study, these results indicated that the adult-type strains have a stronger ability to use plant-derived glycans than infant-type strains. Our work suggests that bifidobacterial carbohydrate metabolism differences resulted in the selective adaptation to the distinct intestinal environment of an adult or breastfed infant. CONCLUSIONS: The present study revealed that the different gut environments can lead to the differences in the polysaccharide utilization in the same strains of bifidobacterial strains, suggesting a further goal of investigating the exact expression of certain enzymes in response to specific carbon sources.

Antimicrobial activities and in vitro properties of cold-adapted Lactobacillus strains isolated from the intestinal tract of cold water fishes of high latitude water areas in Xinjiang, China.

BACKGROUND: There are still a large variety of microorganisms among aquatic animals, especially probiotic lactic acid bacteria in cold water fishes at high latitudes have not been fully developed. Hence, the present study aims to evaluate the probiotic potential of cold-adapted Lactobacillus strains isolated from the intestinal tract of cold water fishes (Xinjiang) and select candidates to be used as new food preservative agents and/or probiotic additives in feeding of aquaculture. RESULTS: A total of 43 Lactobacillus spp. were isolated from 16 kinds of intestinal tract of cold-water fishes. They were characterized by phenotypic methods, identified using Rep-PCR and 16S rRNA gene sequencing as four species: Lactobacillus sakei (22 isolates), Lactobacillus plantarum (16 isolates), Lactobacillus casei (4 isolates) and Lactobacillus paracasei (1 isolate). The in vitro tests included survival in low pH and bile, antimicrobial activity (against Escherichia coli, Salmonella enterica subsp. enterica serovar Typhimurium, Salmonella enterica subsp. enterica, Listeria monocytogenes, and Listeria innocua), resistance to 15 antibiotics and hemolytic tests. Among all 43 lactobacilli isolates, the 22 isolates showed a wide range of antimicrobial activity against 6 different pathogenic strains. There were twenty isolates growing at optimal temperature ranging 16~20 °C, which were initially considered to be cold-adapted strains. Two (2) Lb. sakei strains and 2 Lb. plantarum strains demonstrated the highest survivability after 4 h of exposure at pH 2.0. Most of the tested strains cannot be cultured after exposed into 0.5% bile solution for 4 h, while 2 Lb. plantarum strains (E-HLM-3, CQ-CGC-2) and 1 Lb. sakei strain M-DGM-2 survived even at 2% bile concentration. In addition, the safety assessment showed that 22 strains without any detectable hemolytic activity and resistant to glycopeptides (vancomycin, teicoplanin), levofloxacin, aztreonam, amikacin and oxacillin, while all the studied lactobacilli showed sensitivity to or semi-tolerant to other antibiotics. CONCLUSIONS: Based on all the experiments, 3 strains, including E-HLM-3, CQ-CGC-2, and M-DGM-2 might be a candidate of choice for using in the food preservative agents and/or probiotic additives in feeding of aquaculture.

Habitat-specificity and diversity of culturable cold-adapted yeasts of a cold-based glacier in the Tianshan Mountains, northwestern China.

Asian cold-based glacier yeasts with respect to their abundance, distribution, and taxonomy, in contrast to other continental cryosphere areas, have been little investigated. The present study reports the diversity and phylogeny of culturable cold-adapted yeasts in six cold habitats of the Glacier No.1 in the Tianshan Mountains (northwestern China). Of the total 591 yeast isolates, 401 were identified as basidiomycetous yeasts represented by 41 species of 15 genera, while 190 ascomycetous yeast isolates were assigned to the 8 species of 7 genera. The most prevalent species was Candida akabanensis with a 19.8% frequency of occurrence, followed by Vishniacozyma victoriae (16.4%) and Diutina rugosa (9.98%), of which V. victoriae was the only yeast species common to all six glacial habitats. Variability on the component and abundance of yeast taxa among glacial habitats primarily displayed in four dominant yeast genera, namely Candida, Vishniacozyma, Filobasidium, and Naganishia. However, network analysis illustrated that most of 32 rare yeast populations were habitat-specific, implying that the low-abundance yeast population was more easily influenced by the local habitat conditions (species sorting). Based on indicator species analyses, the subglacial habitat was characterized by psychrotolerant and/or psychrophilic yeast taxa.

Oligosaccharides as co-encapsulating agents: effect on oral Lactobacillus fermentum survival in a simulated gastrointestinal tract.

OBJECTIVES: Four kinds of oligosaccharides were used as co-encapsulating agents to test the effect of extrusion-based microencapsulation on protection of Lactobacillus fermentum L7 against exposure to simulated gastric and intestinal juices as well as long-term refrigeration storage at 4 °C. RESULTS: The combination of alginate with galacto-oligosaccharides, isomalto-oligosaccharides, fructo-oligosaccharides, and xylo-oligosaccharides, or alginate alone exhibited good properties of the beads. The diameters of the cell beads co-encapsulated with oligosaccharides and encapsulated with alginate alone were similar, in the range of 2.34-2.51 mm. However, the encapsulation yield of L. fermentum cells co-encapsulated with oligosaccharides, which was in the range of 79.52-89.75%, was significantly higher than that of cells encapsulated with alginate alone. The capsules were stable in gastric conditions and can disintegrated when exposed to intestinal conditions. Additionally, the viability of microencapsulated cells after exposure to the simulated gastric and intestinal juices as well as long-term refrigeration storage was better than that of free cells, and the viability of cells co-encapsulated with oligosaccharides was better than that of cells encapsulated with alginate alone. Furthermore, fructo-oligosaccharides used as co-encapsulating agent showed the best performance. CONCLUSIONS: Microencapsulating L. fermentum with oligosaccharides protected cells well at a low temperature and offered effective gastrointestinal delivery of probiotics, and thus has the potential to maintain bacterial survival in probiotic products and will provide the research basis for design of effective probiotic-prebiotic combinations to maximize host benefit.

[Phylogenetic and genetic heterogeneity of 23 Acidithiobacillus strains isolated from different geographical locations].

Objective: To study the phylogenetic and genetic heterogeneity of 23 Acidithiobacillus strains from various geographical locations, as well as the relationship between the DNA fingerprinting classification and geographical origin of Acidithiobacillus. Methods: Partial 16S-23S rRNA gene intergenic spacer (ITS) was used to construct corresponding phylogenetic trees based on the sequence homology. rus gene amplification and rep-PCR assay with two different primers (BOXAIR and ERIC) were performed to analyze genetic heterogeneity of Acidithiobacillus strains from diverse environment. Results: Acidithiobacillus revealed a great genetic heterogeneity. The whole isolates were classified into five groups by ITS sequence analysis. This result was similar with that obtained by rep-PCR. Acidithiobacillus ferrooxidans strains were always divided into two groups of phylogenetic and BOXAIR fingerprinting cluster analysis. However, these were clustered one group in the ERIC dendrogram. Genotypic analysis of the rus gene suggested that different iron oxidation pathways have been evolved in these closely related bacteria. Taken together, the iron oxidation pathway of Acidithiobacillus and phylogenetic groups have no obvious correlation. ITS gene has been proven very useful in distinguishing closely related species or subspecies of Acidithiobacillus, to BOXAIR-PCR, which has been recommended as reliable tool for genetic heterogeneity analysis of Acidithiobacillus.

[Phylogenetic and diversity analysis of Acidithiobacillus spp. based on 16S rRNA and RubisCO genes homologues].

Objective: The purpose of the study was to reveal geographic region-related Acidithiobacillus spp. distribution and allopatric speciation. Phylogenetic and diversity analysis was done to expand our knowledge on microbial phylogeography, diversity-maintaining mechanisms and molecular biogeography. Methods: We amplified 16S rRNA gene and RubisCO genes to construct corresponding phylogenetic trees based on the sequence homology and analyzed genetic diversity of Acidithiobacillus spp.. Results: Thirty-five strains were isolated from three different regions in China (Yunnan, Hubei, Xinjiang). The whole isolates were classified into five groups. Four strains were identified as A. ferrivorans, six as A. ferridurans, YNTR4-15 Leptspirillum ferrooxidans and HBDY3-31 as Leptospirillum ferrodiazotrophum. The remaining strains were identified as A. ferrooxidans. Analysis of cbbL and cbbM genes sequences of representative 26 strains indicated that cbbL gene of 19 were two copies (cbbL1 and cbbL2) and 7 possessed only cbbL1. cbbM gene was single copy. In nucleotide-based trees, cbbL1 gene sequences of strains were separated into three sequence types, and the cbbL2 was similar to cbbL1 with three types. Codon bias of RubisCO genes was not obvious in Acidithiobacillus spp.. Conclusion: Strains isolated from three different regions in China indicated a great genetic diversity in Acidithiobacillus spp. and their 16S rRNA/RubisCO genes sequence was of significant difference. Phylogenetic tree based on 16S rRNA genes and RubisCO genes was different in Acidithiobacillus spp..

Application of monoclonal antibody against granulocytes of scallop Chlamys farreri on granulocytes occurrence at different developmental stages and antigenic cross-reactivity of granulocytes in five other bivalve species.

A monoclonal antibody (MAb) 6H7 raised specifically against granulocytes of scallop (Chlamys farreri) was employed to observe granulocyte occurrence successively in blastulae, gastrulae, trochophore larvae, D-shape larvae, umbo-veliger larvae and creeping larvae of C. farreri by immunohistochemistry assay contrasted with H&E stain using semi-thin sections. Moreover, the reactivity of the MAb with granulocytes of C. farreri, Bay scallop Argopecten irradians, Japanese scallop Patinopecten yessoensis, Blue mussel Mytilus edulis, Pacific oyster Crassostrea gigas and Manila clam Ruditapes philippinarum, was detected by immunofluorescence assay (IFA) with differential interference contrast and fluorescent microscopy and flow cytometric immunofluorescence assay (FCIFA). The results showed that positive signals were first observed at D-shape larval stage, about 28 h post fertilization, after that, umbo-veliger larvae exhibited the positive cells with a diameter of 3-5 µm distributed in velum, digestive gland and esophagus. Then in creeping larvae, the number of positive cells increased with average diameter of 5-7 µm, and widely distributed in foot, digestive gland, gills and adductor muscles. No positive signal was found in blastulae, gastrulae and trochophore larvae. The results of IFA and FCIFA showed MAb 6H7 reacted to granulocytes of C. farreri, A. irradians, P. yessoensis and C. gigas, and the positive percentage reactivity were 53 ± 2.5%, 15 ± 2.5%, 12 ± 2.1% and 19 ± 2.1%, respectively, however, no cross-reaction was detected in hemocytes of R. philippinarum and M. edulis.

[Community structure and phylogenetic analysis of cyanobacteria in cryoconite from surface of the Glacier No. 1 in the Tianshan Mountains].

OBJECTIVE: The purpose of this study is to characterize the community composition and phylogenetic analysis of cyanobacteria from supraglacial cryoconite of the Glacier No. 1 in the Tianshan Mountains, China. METHODS: We amplified 16S rRNA genes from the extracted cryoconite DNA by PCR with 2 pairs of cyanobacteria-specific primers. Amplificon was used to construct 16S rRNA genes clone library. The estimation of species richness, diversity indices, and rarefaction curve of the 16S rRNA genes library were determined based on representative phylotypes (OTUs). RESULTS: Analysis of 16S rRNA gene sequences allowed grouping of 101 clones into 12 phylotypes (OTUs) using a cut-off of 97% identity. The phylogenetic analysis revealed that most of sequences affiliated to the order Oscillatoriales and Chroococcales except that three were unclassified. The clone library was dominated by representatives of the order Oscillatoriales (81% of the total clones), and the most abundant organisms within this order were in the genus Phormidium (68 clones) including clones grouping into four phylotypes. The only clone of Chroococcales was closely related to the genus Chamaesiphon with 97% similarity. In addition, comparison of soil chemical properties between different habitats indicated that supraglacial cryoconite supported significantly higher the content of available phosphorus and potassium, nitrate nitrogen and organic matter compared with the forefield of the Glacier No. 1. CONCLUSION: The diversity index of cyanobacteria were relatively high in supraglacial cryoconite of the Glacier No. 1 in the Tianshan Mountains. The community structure was dominated by members of the genus Phormidium. This study may enrich our knowledge on biogeochemical processes and ecological distribution of cyanobacterial populations in glacial ecosystem.

The Biotransformation and Influence on the Functional Activities of Metabolites during the Fermentation of Elaeagnus moorcroftii Wall.ex Schlecht. Juice by Bifidobacterium animalis subsp. lactis HN-3.

Elaeagnus moorcroftii Wall.ex Schlecht. (EWS) has extensive nutrients and functional active ingredients, which makes it an excellent potential substrate for fermentation. The improvement in the antioxidant activity of Elaeagnus moorcroftii Wall.ex Schlecht. juice (EWSJ) fermented by Bifidobacterium animalis subsp. lactis HN-3 (B.an3) could be attributed to the metabolism and biotransformation of plant-based products by the bacterial strain. To reveal the underlying mechanism, non-targeted metabolomics was applied in this study. After fermentation, the structure of downregulated carbohydrates, amino acids, fatty acids, and flavonoids was changed by Bifidobacterium biotransformation (included four reductions, three hydrolyses, four isomerizations, three deglycosidations, and five other reactions). The structure of these converted upregulated products has a higher antioxidant ability to reduce free radicals than their precursors, such as the flavonoids in the form of hydrolyzed conjugates, amino acids with multiple sulfhydryls or hydroxys, carbohydrates with reactive oxygen on benzene rings and fatty acids with unsaturated bonds, short chains, and glycosides. These findings shed light on the mechanism of the metabolism and biotransformation of EWSJ by B.an3, facilitate the study of the interaction between probiotics and fermented plant-based products, and provide a theoretical basis for the development of Bifidobacterium-fermented plant products with stronger functional activities.

Genetic specialization of key bifidobacterial phylotypes in multiple mother-infant dyad cohorts from geographically isolated populations.

Little has been known about symbiotic relationships and host specificity for symbionts in the human gut microbiome so far. Bifidobacteria are a paragon of the symbiotic bacteria biota in the human gut. In this study, we characterized the population genetic structure of three bifidobacteria species from 58 healthy mother-infant pairs of three ethnic groups in China, geographically isolated, by Rep-PCR, multi-locus sequence analysis (MLSA), and in vitro carbohydrate utilization. One hundred strains tested were incorporated into 50 sequence types (STs), of which 29 STs, 17 STs, and 4 STs belong to B. longum subsp. longum, B. breve, and B. animalis subsp. lactis, respectively. The conspecific strains from the same mother-child pair were genetically very similar, supporting the vertical transmission of Bifidobacterium phylotypes from mother to offspring. In particular, results based on allele profiles and phylogeny showed that B. longum subsp. longum and B. breve exhibited considerable intraspecies genetic heterogeneity across three ethnic groups, and strains were clustered into ethnicity-specific lineages. Yet almost all strains of B. animalis subsp. lactis were incorporated into the same phylogenetic clade, regardless of ethnic origin. Our findings support the hypothesis of co-evolution between human gut symbionts and their respective populations, which is closely linked to the lifestyle of specific bacterial lineages. Hence, the natural and evolutionary history of Bifidobacterium species would be an additional consideration when selecting bifidobacterial strains for industrial and therapeutic applications.

Whole-genome resequencing and transcriptional profiling association analysis revealed the intraspecies difference response to oligosaccharides utilization in Bifidobacterium animalis subsp. lactis.

Introduction: As prebiotics, oligosaccharides are frequently combined with Bifidobacterium to develop synbiotic products. However, a highly diverse gene repertoire of Bifidobacterium is involved in sugar catabolism, and even phylogenetically close species may differ in their sugar utilization capabilities. To further explore the mechanism underlying the differences in Bifidobacterium animalis subsp. lactis oligosaccharide metabolism. Methods: This study screened strains with differential oligosaccharide metabolism. Subsequently, these strains were subjected to genome-wide resequencing and RT-qPCR. Results: The resequencing results indicated that the subspecies of B. animalis subsp. lactis had a high genome similarity. The RT-qPCR results revealed that glycosidase genes exhibited consistency in the phenotype of metabolism at the transcriptional level; the better the growth of the strains on the oligosaccharides, the higher was the expression of glycosidase genes related to the oligosaccharides. Our results suggested that the differences in the gene transcription levels led to intraspecies differences in the ability of the strains to metabolize oligosaccharides even when they belonged to the same subspecies. Discussion: Future studies with more sample size could generalizable the conclusion to all B. animalis subsp. lactis strains, thus would lay the theoretical foundation for the utilization of the B. animalis subsp. lactis strain as probiotics and the development of synbiotic products.

[Isolate and genetic heterogeneity of psychrotrophic lactic acid bacteria from the intestinal tract of cold-water fishes from the Eerqisi river, Xinjiang].

OBJECTIVE: The purpose of this study was to select cold-adapted lactic acid bacteria (LAB) from the intestinal tract of cold-water fishes from the Eerqisi river Alatai, Xinjiang. METHODS: By using culture medium MRS and Elliker, isolation of lactic acid bacteria (LAB) from 9 intestinal canal of cold-water fishes was carried out. Taxonomic identity and genetic diversity of strains isolated were determined by partial 16S rRNA gene sequences and rep-PCR with three different kinds of primers named BOX, (GTG)5, ERIC. RESULTS: A total of 78 psychrotrophic isolates were obtained. Among them, 24 isolates had characteristics of LAB and showed the optimal growth temperature ranging from 15 to 24 degrees C. The phylogenesis result showed that 24 strains belonged to 6 Genuses, Carnobacterium (3 strains), Lactococcus (9 strains), Enterococcus (7 strains), Brochothrix (1 strain), Weissella (2 strains), Streptococcus (2 strains), rep-PCR clustering analysis showed that Lactococcus and Enterococcus strains were from different Species. Lactococcus were belonged to 4 species while Enterococcus assigned to 2 species. CONCLUSION: The phylogenetic diversity of cold-adapted LAB from the intestinal tract of cold-water fishes from the Eerqisi river in the Alatai Xinjiang was relatively abundant.

[Phylogenetic and physiological diversity of cold-adapted bacteria producing protease from sediments of the bottom layer of the glacier no. 1 in the Tianshan mountains].

OBJECTIVE: We characterized proteolytic bacteria isolates from sediments of the bottom layer of the Glacier No. 1 in the Tianshan Mountains, China. Physiological test and phylogenetic analysis were undertaken to expand our knowledge on diversity and ecological distribution of psycrotrophic and psycrophlic bacteria populations. METHODS: Using the screening media containing skim milk, we screened cold-adapted strains producing protease. Taxonomic identity and genetic variability of strains isolated was determined by partial 16S rRNA gene sequences and repetitive-element PCR fingerprint. RESULTS: Of the total 125 cold-adapted bacterial isolates, high levels of protease activity were observed from 27 isolates at optimal growth temperatures ranging from 15 to 24 degrees C in plate assay. Among 27 protease-producing strains, only 6 isolates were psychrophilic. The 16S rRNA gene phylogenetic analysis revealed that protease-producing isolates belonged to 5 phyum, namely alpha, beta and gamma of Proteobacteria, Actinobacteria and Cytophaga-Flexibacter-Bacteroides. They are affiliated to the genera Pseudomonas, Polaromonas, Brevundimonas, Rholococces, Cryobacterium, Kocuria, Arthrobacter, Chryseobacterium and Flavobacterium. The populations of the predominant cultivated protease-producing bacteria are the Pseudomonas spp. (40.7%). CONCLUSION: The results enriched our knowledge on the phylogenetic and physiological diversity of cold-adapted strains producing protease in cold environments.

Chemical Structure and Microscopic Morphology Changes of Dyed Wood Holocellulose Exposed to UV Irradiation.

Dyed wood is prone to photoaging when exposed to UV irradiation which decreases its decorative effect and service life. Holocellulose, as the main component of dyed wood, has a photodegradation behavior which is still unclear. To investigate the effect of UV irradiation on chemical structure and microscopic morphology changes of dyed wood holocellulose, Maple birch (Betulacostata Trautv) dyed wood and holocellulose were exposed to UV accelerated aging treatment; the photoresponsivity includes crystallization, chemical structure, thermal stability, and microstructure were studied. Results showed that UV radiation has no significant effect on the lattice structure of dyed wood fibers. The wood crystal zone diffraction 2θ and layer spacing was basically unchanged. With the UV radiation time extension, the relative crystallinity of dyed wood and holocellulose showed a trend of increasing first and then decreasing, but the overall change was not significant. The relative crystallinity change range of the dyed wood was not more than 3%, and the dyed holocellulose was not more than 5%. UV radiation caused the molecular chain chemical bond in the non-crystalline region of dyed holocellulose to break, the fiber underwent photooxidation degradation, and the surface photoetching feature was prominent. Wood fiber morphology was damaged and destroyed, finally leading to the degradation and corrosion of the dyed wood. Studying the photodegradation of holocellulose is helpful to understand the photochromic mechanism of dyed wood, and, further, to improve its weather resistance.

Genetic-Phenotype Analysis of Bifidobacterium bifidum and Its Glycoside Hydrolase Gene Distribution at Different Age Groups.

Human gut microbiota interfere with host development and aging. Bifidobacterium is a microbial genus found in the human digestive tract that has probiotic activities such as improving constipation and enhancing immunity. The species and numbers present change with age, but there has been limited research on probiotic gut microbiota at specific ages. This study analyzed the distribution of 610 bifidobacteria in subjects in several age groups (0-17, 18-65, and 66-108 y) using 486 fecal samples and determined the distribution of glycoside hydrolases based on genetic analysis of strains representing 85% of the Bifidobacterium species abundance in each age group. 6'-Sialyllactose is a major component of acidic breast milk oligosaccharides, which can promote human neurogenesis and bifidobacteria growth. Using genotypic and phenotypic association analysis, we investigated the utilization of 6'-sialyllactose by six B. bifidum strains isolated from subjects 0-17 and 18-65 y. A comparative genomic analysis of the six B. bifidum strains revealed differences in genomic features across age groups. Finally, the safety of these strains was evaluated by antibiotic gene and drug resistance phenotype analysis. Our results reveal that the distribution of glycoside hydrolase genes in B. bifidum varies with age, thus affecting the phenotypic results. This provides important insights for the design and application of probiotic products for different ages.

Prebiotic activity of chitooligosaccharides and their ability to alleviate necrotizing enterocolitis in newborn rats.

Chitooligosaccharides (COS) have many bioactive functions and favorable prospects in the fields of biomedicine and functional foods. In this study, COS was found to significantly improve the survival rate of neonatal necrotizing enterocolitis (NEC) model rats, alter the composition of the intestinal microbiota, inhibit the expression of inflammatory cytokines, and alleviate intestinal pathological injury. In addition, COS also increased the abundance of Akkermansia, Bacteroides, and Clostridium sensu stricto 1 in the intestines of normal rats (the normal rat model is more universal). The in vitro fermentation results found that COS was degraded by the human gut microbiota to promote the abundance of Clostridium sensu stricto 1 and produced numerous short-chain fatty acids (SCFAs). In vitro metabolomic analysis revealed that COS catabolism was associated with significant increases in 3-hydroxybutyrate acid and γ-aminobutyric acid. This study provides evidence for the potential of COS as a prebiotic in food products and to ameliorate NEC development in neonatal rats.

Shwachman Diamond Syndrome with Arrhythmia as the First Manifestation a Case Report and Literature Review.

Objective: Analyze the different clinical manifestations and genetic characteristics of Shwachman diamond syndrome (SDS). Methods: The clinical data of a case of neonatal onset Shwachman diamond syndrome with arrhythmia as the first manifestation were retrospectively analyzed, and the relevant literature was reviewed to summarize the clinical manifestations, genetic characteristics and treatment of Shwachman diamond syndrome. Results: The patient, female, age 1 month 24 days, with ventricular arrhythmia as the first manifestation, accompanied by growth retardation, liver damage, and persistent decrease in peripheral blood neutrophil count (< 1.5 × 109/l), no pancreatic exocrine gland dysfunction at the initial stage of the disease. Gene detection showed that the SBDS gene chr7:66,459,197, c.258+2T > C homozygous variation. Conclusion: Although the classic manifestations of Shwachman diamond syndrome are pancreatic exocrine insufficiency, pancreatic adiposis and unexplained neutropenia, its clinical manifestations are complex and diverse, involving multiple systems. For suspected children, early genetic examination is helpful for subsequent diagnosis and treatment.