16S rRNA gene sequencing and machine learning reveal correlation between drug abuse and human host gut microbiota.

Over the past few years, there has been increasing evidence highlighting the strong connection between gut microbiota and overall well-being of the host. This has led to a renewed emphasis on studying and addressing substance use disorder from the perspective of brain-gut axis. Previous studies have suggested that alcohol, food, and cigarette addictions are strongly linked to gut microbiota and faecal microbiota transplantation or the use of probiotics achieved significant efficacy. Unfortunately, little is known about the relationship between drug abuse and gut microbiota. This paper aims to reveal the potential correlation between gut microbiota and drug abuse and to develop an accurate identification model for drug-related faeces samples by machine learning. Faecal samples were collected from 476 participants from three regions in China (Shanghai, Yunnan, and Shandong). Their gut microbiota information was obtained using 16S rRNA gene sequencing, and a substance use disorder identification model was developed by machine learning. Analysis revealed a lower diversity and a more homogeneous gut microbiota community structure among participants with substance use disorder. Bacteroides, Prevotella_9, Faecalibacterium, and Blautia were identified as important biomarkers associated with substance use disorder. The function prediction analysis revealed that the citrate and reductive citrate cycles were significantly upregulated in the substance use disorder group, while the shikimate pathway was downregulated. In addition, the machine learning model could distinguish faecal samples between substance users and nonsubstance users with an AUC = 0.9, indicating its potential use in predicting and screening individuals with substance use disorder within the community in the future.

Sphingomonas sp. Hbc-6 alters physiological metabolism and recruits beneficial rhizosphere bacteria to improve plant growth and drought tolerance.

Drought poses a serious threat to plant growth. Plant growth-promoting bacteria (PGPB) have great potential to improve plant nutrition, yield, and drought tolerance. Sphingomonas is an important microbiota genus that is extensively distributed in the plant or rhizosphere. However, the knowledge of its plant growth-promoting function in dry regions is extremely limited. In this study, we investigated the effects of PGPB Sphingomonas sp. Hbc-6 on maize under normal conditions and drought stress. We found that Hbc-6 increased the biomass of maize under normal conditions and drought stress. For instance, the root fresh weight and shoot dry weight of inoculated maize increased by 39.1% and 34.8% respectively compared with non-inoculated plant, while they increased by 61.3% and 96.3% respectively under drought conditions. Hbc-6 also promoted seed germination, maintained stomatal morphology and increased chlorophyll content so as to enhance photosynthesis of plants. Hbc-6 increased antioxidant enzyme (catalase, superoxide, peroxidase) activities and osmoregulation substances (proline, soluble sugar) and up-regulated the level of beneficial metabolites (resveratrol, etc.). Moreover, Hbc-6 reshaped the maize rhizosphere bacterial community, increased its richness and diversity, and made the rhizosphere bacterial community more complex to resist stress; Hbc-6 could also recruit more potentially rhizosphere beneficial bacteria which might promote plant growth together with Hbc-6 both under normal and drought stress. In short, Hbc-6 increased maize biomass and drought tolerance through the above ways. Our findings lay a foundation for exploring the complex mechanisms of interactions between Sphingomonas and plants, and it is important that Sphingomonas sp. Hbc-6 can be used as a potential biofertilizer in agricultural production, which will assist finding new solutions for improving the growth and yield of crops in arid areas.

Sphingomonas psychrotolerans sp. nov., isolated from root surface of Leontopodium leontopodioides in the Tianshan Mountains, Xinjiang, China.

A novel rod-shaped, Gram-stain-negative, aerobic bacterial strain, designated Cra20T, was isolated from the root surface of Leontopodium leontopodioides collected in the Tianshan Mountains, Xinjiang, PR China. Phylogenetic analysis based on 16S rRNA gene sequences, indicated that strain Cra20T was affiliated with the genus Sphingomonas, and was most closely related to Sphingomonas gei ZFGT-11T (99.0 %), Sphingomonas naasensis KIS18-15T (97.8%) and Sphingomonas kyeonggiensis THG-DT81T (97.2 %). The average nucleotide identity values between strain Cra20T, S. gei ZFGT-11T, S. naasensis KIS18-15T and S. kyeonggiensis THG-DT81T were 86.2, 84.2 and 78.2 %, respectively. The genomic DNA G+C content of strain Cra20T was 65.6 mol% (whole genome sequence), and Q-10 was the predominant ubiquinone. The major cellular fatty acids of strain Cra20T were summed feature 8 (comprising C18 : 1 ω6c and/or C18 : 1 ω7c, 67.3 %) and C14 : 0 2-OH (6.4 %). On the basis of genotypic, phenotypic and biochemical data, strain Cra20T is considered to represent a novel species of the genus Sphingomonas, for which the name Sphingomonas psychrotolerans sp. nov. is proposed. The type strain is Cra20T (=CGMCC 1.15510T=NBRC 112697T).

Culture-dependent and culture-independent characterization of bacterial community diversity in different types of sandy lands: the case of Minqin County, China.

BACKGROUND: Minqin is suffering from a serious desertification, whereas the knowledge about its bacterial community is limited. Herein, based on Nitraria tangutorum and Haloxylon ammodendron from Minqin, the bacterial community diversities in fixed sandy land, semi-fixed sandy land and shifting sandy land were investigated by combining with culture-dependent and culture-independent methods. RESULTS: Minqin stressed with high salinity and poor nutrition is an oligotrophic environment. Bacterial community in Minqin was shaped primarily by the presence of host plants, whereas the type of plant and sandy land had no marked effect on those, which displayed a better survival in the rhizospheres of N. tangutorum and H. ammodendron. The dominant groups at phyla level were Actinobacteria, Firmicutes, Proteobacteria, Bacteroidetes, Planctomycetes, Chloroflexi, Acidobacteria and Candidate_division_TM7. The abundance of Firmicutes with ability of desiccation-tolerance was significantly higher in harsh environment, whereas Bacteroidetes were mainly distributed in areas with high nutrient content. The abundances of Proteobacteria and Bacteroidetes were relatively high in the rhizospheres of N. tangutorum and H. ammodendron, which had more plant-growth promoting rhizobacteria. A large number of Actinobacteria were detected, of which the most abundant genus was Streptomyces. The physicochemical factors related to the diversity and distribution of the bacterial community were comprehensively analyzed, such as pH, electrical conductivity, soil organic matter, C/N and sand, and the results indicated that Minqin was more suitable for the growth of N. tangutorum, which should be one of most important sand-fixing plants in Minqin. CONCLUSIONS: The bacterial community diversities in different types of sandy lands of Minqin were comprehensively and systematically investigated by culture-dependent and culture-independent approaches, which has a great significance in maintaining/restoring biological diversity.

Complete genome sequence of Sphingomonas sp. Cra20, a drought resistant and plant growth promoting rhizobacteria.

Sphingomonas sp. Cra20 is a rhizobacteria isolated from the root surface of Leontopodium leontopodioides in the Tianshan Mountains of China and was found to influence root system architecture. We analyzed its ability for plant-growth promotion and the molecular mechanism involved by combining the physiological and genome information. The results indicated that the bacterium enhanced the drought resistance of Arabidopsis thaliana and promoted growth mainly through the strain-released volatile organic compounds. The genome consisted of one circular chromosome and one circular plasmid, containing a series of genes related to the plant-growth promotion. Furthermore, multiple copies of cold-associated genes, general stress response genes, oxidative stress genes and DNA repair mechanisms supported its survivability in extreme environments. In addition, the strain had the ability to degrade xylene and 2, 4-D via a variety of monooxygenases and dioxygenases. This provides further information and will promote the application of Cra20 as a biofertilizer in agriculture.

Effect of aridity and dune type on rhizosphere soil bacterial communities of Caragana microphylla in desert regions of northern China.

Understanding the response of soil properties and bacterial communities in rhizosphere soil to aridity and dune types is fundamental to desertification control. This study investigated soil properties and bacterial communities of both rhizosphere and bulk soils of Caragana microphylla from four sites with different aridity indices, and one site with three different types of dunes. All sites were located in the desert regions of northern China. The results indicated that compared with the bulk soil, the soil nutrient content of rhizosphere, especially the content of total phosphorus, was generally significantly improved in different desertification environments. The bacterial richness and diversity were also higher than those of bulk soil, especially in arid regions and fixed dunes. Firmicutes, Actinobacteria, Proteobacteria, and Acidobacteria were the most dominant phyla in all samples. The regression analyses showed that at different sites, soil total organic C, total N, Na+, and total P played key roles in determining the bacterial community structure while total organic carbon, electronic conductivity, pH and total phosphorus were the dominant factors at the different dunes. The results further revealed that the dominant phyla strongly affected by environmental factors at different sites were Acidobacteria, Gemmatimonadetes, and Actinobacteria among which, Acidobacteria and Gemmatimonadetes were negatively correlated with Na+ content. At different types of dunes, Actinobacteria, Planctomycetes, and Gemmatimonadetes were particularly affected by environmental factors. The increased abundance of Actinobacteria in the rhizosphere soil was mainly caused by the decreased soil pH.

BYPASS1-LIKE, A DUF793 Family Protein, Participates in Freezing Tolerance via the CBF Pathway in Arabidopsis.

The C-REPEAT BINDING FACTOR signaling pathway is strictly modulated by numerous factors and is essential in the cold response of plants. Here, we show that the DUF793 family gene BYPASS1-LIKE modulates freezing tolerance through the CBFs in Arabidopsis. The expression of B1L was rapidly induced under cold treatment. Comparing to wild type, B1L knockout mutants were more sensitive to freezing treatment, whereas B1L-overexpressing lines were more tolerant. The expression of CBFs and CBF target genes was significantly decreased in b1l mutant. Using yeast two-hybrid screening system, 14-3-3λ was identified as one of proteins interacting with B1L. The interaction was confirmed with bimolecular fluorescence complementation assay and co-immunoprecipitation assay. Biochemical assays revealed that b1l mutation promoted the degradation of CBF3 compared to wild type, whereas 14-3-3κλ mutant and b1l 14-3-3κλ mutant suppressed the degradation of CBF3. Consistently, 14-3-3κλ and b1l 14-3-3κλ mutants showed enhanced freezing tolerance compared to wild type. These results indicate that B1L enhances the freezing tolerance of plants, at least partly through stabilizing CBF. Our findings improve our understanding of the regulation of CBF in response to cold stress.

Sphingomonas sp. Cra20 Increases Plant Growth Rate and Alters Rhizosphere Microbial Community Structure of Arabidopsis thaliana Under Drought Stress.

The rhizosphere is colonized by a mass of microbes, including bacteria capable of promoting plant growth that carry out complex interactions. Here, by using a sterile experimental system, we demonstrate that Sphingomonas sp. Cra20 promotes the growth of Arabidopsis thaliana by driving developmental plasticity in the roots, thus stimulating the growth of lateral roots and root hairs. By investigating the growth dynamics of A. thaliana in soil with different water-content, we demonstrate that Cra20 increases the growth rate of plants, but does not change the time of reproductive transition under well-water condition. The results further show that the application of Cra20 changes the rhizosphere indigenous bacterial community, which may be due to the change in root structure. Our findings provide new insights into the complex mechanisms of plant and bacterial interactions. The ability to promote the growth of plants under water-deficit can contribute to the development of sustainable agriculture.

Lysobacter psychrotolerans sp. nov., isolated from soil in the Tianshan Mountains, Xinjiang, China.

A novel aerobic bacterial strain, designated ZS60T, with long, rod-shaped, Gram-staining-negative, aerobic cells was isolated from the soil in the Tianshan Mountains, Xinjiang, China. Phylogenetic analysis based on its 16S rRNA gene sequence indicated that strain ZS60T was affiliated with the genus Lysobacter, and was most closely related to Lysobacter daejeonensis GH1-9T (96.9 %), Lysobacter caeni BUT-8T (96.8 %) and Lysobacter ruishenii CTN-1T (96.7 %). The average nucleotide identity values between strain ZS60T, L. daejeonensis GH1-9T and L. ruishenii CTN-1T were 78.14 and 78.39 %, respectively. The DNA-DNA relatedness between strain ZS60T, L. daejeonensis GH1-9T and L. caeni BUT-8T were 44.8 and 39.1 %, respectively. The genomic DNA G+C content of the strain ZS60T was 67.7 mol% (draft genome sequence), and Q-8 was the predominant ubiquinone. The major cellular fatty acids of strain ZS60T were iso-C15 : 0 (23.4 %), iso-C17 : 0 (17.2 %) and iso-C17 : 1 ω9c (12.6 %). On the basis of genotypic, phenotypic and biochemical data, strain ZS60T is considered to represent a novel species of the genus Lysobacter, for which the name Lysobacterpsychrotolerans sp. nov. is proposed. The type strain is ZS60T (=CGMCC 1.15509T=NBRC 112614T).

[Effect of Manual Acupuncture Stimulation of Single Acupoint or Acupoints Combination on Intestinal Movement in Slow Transit Constipation Mice].

OBJECTIVE: To observe the effect of acupuncture stimulation of different acupoints or acupoint groups on intestinal locomotor in slow transit constipation (STC) mice, so as to provide experimental evidence for demonstrating the synergic function of acupoint combination. METHODS: A total of 190 Kunming mice were randomized into 19 groups:normal control, model, uni-"Quchi" (LI 11), uni-"Shangjuxu" (ST 37), uni-"Tianshu"(ST 25), and uni-"Dachangshu"(BL 25) groups, for analyzing the effect of single acupoint; normal control, model, uni-ST 25+uni-BL 25, uni-LI 11+uni-ST 37, bi-ST 25, bi-BL 25, bi-LI 11, and bi-ST 37 groups, for comparing the effect between single acupoint and two acupoints combination; normal control, model, bi-ST 25+bi-BL 25, bi-LI 11+bi-ST 37, and uni-LI 11+uni-ST 37+uni-ST 25 +uni-BL 25 groups, for comparing the effect between four acupoints and two acupoints combinations (10 mice/group). The STC model was established by intragastric administration of compound diphenoxylate suspension (1 mg/100 g), once daily for 2 days. Manual acupuncture needle stimulation (200 twirling times/min for 1 min) was applied to the abovementioned unilateral or bilateral acupoints twice daily for 7 times. The first defecation time, the defecation grain number in 12 h and the intestinal propulsion rate were determined using activated carbon gavage. RESULTS: Compared with the normal group, the first defecation time was significantly increased in the STC model group (P<0.01), while the 12 h defecation grain number and the intestinal propulsion rate were considerably decreased in the model group (P<0.01). After manual acupuncture intervention, the first defecation time was notably shortened in the uni-LI 11, uni-ST 37, uni-ST 25, uni-BL 25, bi-ST 25, bi-BL 25, bi-LI 11, bi-ST 37, uni-ST 25+uni-BL 25, uni-LI 11+uni-ST 37, bi-ST 25+bi-BL 25, bi-LI 11+bi-ST 37 and the uni-ST 25+uni-BL 25+uni-LI 11+uni-ST 37 groups compared with the model group (P<0.05), while both the 12 h defecation grain number and intestinal propulsion rate were considerably increased in the abovementioned 13 acupuncture groups (P<0.05, P<0.01). The effects of uni-ST 25+uni-BL 25 and uni-LI 11+uni-ST 37 were significantly superior to those of bi-ST 25, bi-BL 25, bi-LI 11 and bi-ST 37 groups, and those of the uni-ST 25+uni-BL 25+uni-LI 11+uni-ST 37 group were markedly superior to those of bi-ST 25+bi-BL 25 and bi-LI 11+bi-ST 37 groups in shortening the first defecation time and in increasing the 12 h defecation grain number and intestinal propulsion rate (P<0.05). CONCLUSIONS: Acupuncture stimulation of LI 11, ST 37, ST 25 and BL 25 can improve constipation in STC mice, and the effect of two acupoints combination is significantly superior to that of the corresponding bilateral single acupoint, and that of the 4 unilateral single acupoint combination is obviously superior to that of two bilateral acupoints combination, suggesting a synergistic action of acupuncture stimulation.

Epilithonimonas psychrotolerans sp. nov., isolated from alpine permafrost.

A bacterial strain, designated TSBY 57T, was isolated during a study on the phylogenetic diversity of culturable bacteria from alpine permafrost in Tianshan Mountains, China, and was classified by means of a polyphasic taxonomic approach. The novel strain was found to belong to the genus Epilithonimonas and was distinguished from recognized species of this genus. Strain TSBY 57T grew aerobically, at 0-30 °C, with 0-1.5% (w/v) NaCl and at pH 6-8.Cells were Gram-stain-negative, non-motile, non-spore-forming rods. Compared with the reference strains, the novel strain was psychrotolerant. The predominant fatty acids were summed feature 3 (consisting of C16:1ω7c and/or C16:1ω6c), anteiso-C15:0 and iso-C15:0.The sole respiratory quinone was MK-6.Phosphatidylethanolamine was predominant in the polar lipid profile of strain TSBY 57T. These chemotaxonomic traits were in good agreement with the characteristics of the genus Epilithonimonas. On the basis of 16S rRNA gene sequence similarity, strain TSBY 57T was a member of the genus Epilithonimonas and was closely related to Epilithonimonas tenax DSM 16811T (99.0%), Epilithonimonas ginsengisoli DCY78T (98.6%) and Epilithonimonas lactis H1T (98.5%). However, DNA-DNA reassociation values between strain TSBY 57T and E. tenax DSM 16811T, E. ginsengisoli DCY78T and E. lactis H1T were 39.5 ± 2.6, 37.7 ± 1.0 and 37.3 ± 1.1%, respectively. The G+C content of the DNA was 34.4 ± 0.2  mol%. Based on data from this polyphasic taxonomic study, strain TSBY 57T represents a novel species of the genus Epilithonimonas, for which the name Epilithonimonas psychrotolerans sp. nov. is proposed. The type strain is TSBY 57T ( = NRRL B-51307T=CCTCC AB 207182T).

Using the properties of soil to speed up the start-up process, enhance process stability, and improve the methane content and yield of solid-state anaerobic digestion of alkaline-pretreated poplar processing residues.

BACKGROUND: Solid-state anaerobic digestion (SS-AD) was initially adopted for the treatment of municipal solid waste. Recently, SS-AD has been increasingly applied to treat lignocellulosic biomass, such as agricultural and forestry residues. However, studies on the SS-AD process are few. In this study, the process performance and methane yield from SS-AD of alkaline-pretreated poplar processing residues (PPRs) were investigated using the properties of soil, such as buffering capacity and nutritional requirements. RESULTS: The results showed that the lignocellulosic structures of the poplar sample were effectively changed by NaOH pretreatment, as indicated by scanning electron microscopy and Fourier transform infrared spectra analysis. The start-up was markedly hastened, and the process stability was enhanced. After NaOH pretreatment, the maximum methane yield (96.1 L/kg volatile solids (VS)) was obtained under a poplar processing residues-to-soil sample (P-to-S) ratio of 2.5:1, which was 29.9% and 36.1% higher than that of PPRs (74.0 L/kg VS) and that of experiments without NaOH pretreatment (70.6 L/kg VS), respectively. During steady state, the increase in the methane content of the experiment with a P-to-S ratio of 2.5:1 was 4.4 to 50.9% higher than that of the PPRs. Degradation of total solids and volatile solids ranged from 19.3 to 33.0% and from 34.9 to 45.9%, respectively. The maximum reductions of cellulose and hemicellulose were 52.6% and 42.9%, respectively, which were in accordance with the maximal methane yield. T 80 for the maximum methane yield for the experiments with NaOH pretreatment was 11.1% shorter than that for the PPRs. CONCLUSIONS: Pretreatment with NaOH and addition of soil led to a significant improvement in the process performance and the methane yield of SS-AD of PPRs. The changes in lignocellulosic structures induced by NaOH pretreatment led to an increase in methane yield. For the purpose of practical applications, SS-AD with soil addition is a convenient, economical, and practical technique.

[Exterior-interior correlation of "heart" and body surface based on researches of classic literature and modern animal experiments].

Exterior-interior relationship of meridians and zangfu organs is an important component of the theory of acupuncturology in Chinese medicine. According to the descriptions in classic works of Chinese medicine and findings of modern experimental researches, in the present paper, the authors analyzed the close association between the "Heart" and "Small Intestine", exterior-interior correlation between the Heart Meridian and Small Intestine Meridian, and between the "Heart" and body surface (acupoints), limbs, five sensory organs, etc. In addition, the authors also summarized the underlying mechanisms of the above-mentioned exterior-interior relationship of the "Heart" and put forward some proposals for the future researches.

Anaerobic digestion of poplar processing residues for methane production after alkaline treatment.

Poplar processing residues were used for methane production by anaerobic digestion after alkaline treatment and methane production was measured. The highest methane production of 271.9 L/kg volatile solid (VS) was obtained at conditions of 35 g/L and 5.0% NaOH, which was 113.8% higher than non-alkaline treated samples, and 28.9% higher than that of corn straw, which is the conventional anaerobic digestion material in China. The maximal enhancement of 275.5% obtained at conditions of 50 g/L and 7.0% NaOH. Degradation of cellulose, hemicellulose and lignin after treatment increased by 4.0-9.0%, 3.3-6.2%, and 11.1-20.5%, respectively, with NaOH dose ranged from 3.0% to 7.0%. Scanning electron microscopy (SEM), FTIR spectra and Crystallinity measurements showed that the lignocellulosic structures were disrupted by NaOH. The results indicate poplar processing residues might be an efficient substrate for methane production after alkaline treatment.

Paracoccus tibetensis sp. nov., isolated from Qinghai-Tibet Plateau permafrost.

Strain Tibet-S9a3(T) was isolated from Qinghai-Tibet Plateau permafrost, China. The isolate was a Gram-negative, non-motile, non-spore-forming short rod. The 16S rRNA gene sequence indicated that strain Tibet-S9a3(T) was a member of the genus Paracoccus and was closely related to Paracoccus aestuarii B7(T) (98.2 % 16S rRNA gene sequence similarity), 'P. beibuensis' JLT1284 (97.9 %), P. homiensis DD-R11(T) (97.4 %), P. zeaxanthinifaciens ATCC 21588(T) (97.4 %) and other type strains of the genus (93.7-96.7 %). The G+C content of the genomic DNA was 69.1 mol% and the major isoprenoid quinone was ubiquinone-10. The major fatty acids were C18 : 1ω7c (87.6 %), C18 : 0 (4.3 %) and C10 : 0 3-OH (2.0 %). DNA-DNA relatedness between strain Tibet-S9a3(T) and P. aestuarii B7(T) was 37.9 %. On the basis of phenotypic and genotypic characteristics, it is suggested that strain Tibet-S9a3(T) represents a novel species of the genus Paracoccus, for which the name Paracoccus tibetensis sp. nov. is proposed. The type strain is Tibet-S9a3(T) ( = CGMCC 1.8925(T)  = NBRC 105667(T)).

Cloning, expression and characterization of trehalose-6-phosphate phosphatase from a psychrotrophic bacterium, Arthrobacter strain A3.

A trehalose-6-phosphate phosphatase (TPP) gene, otsB, from a psychrotrophic bacterium, Arthrobacter strain A3, was identified. The product of this otsB gene is 266 amino acids in length with a calculated molecular weight of 27,873 Da. The protein was expressed in Escherichia coli and purified to apparent homogeneity. The purified recombinant TPP catalyzed the dephosphorylation of trehalose-6-phosphate to form trehalose and showed a broad optimum pH range from 5.0 to 7.5. This enzyme also showed an absolute requirement for Mg(2+) or Co(2+) for catalytic activity. The recombinant TPP had a maximum activity at 30 °C and maintained activity over a temperature range of 4-30 °C. TPP was generally heat-labile, losing 70 % of its activity when subjected to heat treatment at 50 °C for 6 min. Kinetic analysis of the Arthrobacter strain A3 TPP showed ~tenfold lower K (m) values when compared with values derived from other bacterial TPP enzymes. The highest k (cat)/K (m) value was 37.5 mM(-1) s(-1) (repeated three times), which is much higher than values published for mesophilic E. coli TPP, indicating that the Arthrobacter strain A3 TPP possessed excellent catalytic activity at low temperatures. Accordingly, these characteristics suggest that the TPP from the Arthrobacter strain A3 is a new cold-adapted enzyme. In addition, this is the first report characterizing the enzymatic properties of a TPP from a psychrotrophic organism.

Chryseobacterium xinjiangense sp. nov., isolated from alpine permafrost.

Strain TSBY 67(T) was isolated during a study on the phylogenetic diversity of culturable bacteria from alpine permafrost in Tianshan Mountains, China. On the basis of 16S rRNA gene sequence analysis, strain TSBY 67(T) was closely related to members of the genus Chryseobacterium and exhibited 96.8 % 16S rRNA gene sequence similarity to Chryseobacterium aquaticum 10-46(T) and Chryseobacterium soldanellicola PSD 1-4(T). Strain TSBY 67(T) grew aerobically, at 4-37 °C, with 0-2 % NaCl and at pH 6-8. Cells were Gram-staining negative, non-motile and non-spore-forming rods. The dominant cellular fatty acids were iso-C(15 : 0) (26.9 %), iso-C(17 : 0) 3-OH (16.1 %) and iso-C(17 : 1)ω9c (15.4 %). The G+C content of the DNA was 33.5 mol%. Strain TSBY 67(T) was distinguishable from its closest phylogenetic neighbours by a combination of phenotypic characteristics. Therefore, strain TSBY 67(T) represents a novel species of the genus Chryseobacterium, for which the name Chryseobacterium xinjiangense sp. nov. is proposed. The type strain is TSBY 67(T) ( = NRRL B-51308(T) = CCTCC AB 207183(T)).

Optimization of electroporation conditions for Arthrobacter with plasmid PART2.

A prerequisite for genetic studies of Arthrobacter is a high efficiency transformation system that allows for DNA transfer, transposon mutagenesis, and expression of specific genes. In this study, we develop a detailed electroporation method through a systematic examination of the factors involved in the entire electroporation process. Key features of this procedure, including the addition of penicillin to cells during the early log phase of growth and the presence of 0.5M sorbitol in the electroporation and recovery media, produced the greatest increases in transformation efficiency and consistency of results. The transformation rate also varied depending on the electrical parameters, DNA concentration, and recovery time period. Using optimum conditions, we generally achieved an efficiency of 6.8 × 10(7) transformants per microgram of PART2 for Arthrobacter sp. A3. This protocol was also successfully applied to other Arthrobacter species. Therefore, we conclude that the proposed method is rapid, simple and convenient, which allows a transformation trial to be accomplished in minutes.

Effect of inoculation with the endophyte Clavibacter sp. strain Enf12 on chilling tolerance in Chorispora bungeana.

Endophytic bacteria have been shown to increase resistance against biotic stress and tolerance to abiotic stress in many plants. The objective of this study was to evaluate the effect of an endophytic bacterium, Clavibacter sp. strain Enf12, in regenerated plantlets of Chorispora bungeana subjected to chilling stress (0°C). Aerial biomass and physiological markers for chilling stress, such as electrolyte leakage, lipid peroxidation, reactive oxygen species (ROS) accumulation, proline content and activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), guaiacol peroxidase (EC 1.11.1.7) and ascorbate peroxidase (EC 1.11.1.11), were assessed. We demonstrated that Clavibacter sp. strain Enf12 was capable of colonizing internal tissues of regenerated plantlets of C. bungeana and maintained stable population densities under both normal (20°C) and chilling (0°C) conditions. Inoculation enhanced plantlet growth under both conditions and significantly attenuated the chilling-induced electrolyte leakage, lipid peroxidation and ROS accumulation. The endophyte significantly increased the activities of antioxidant enzymes and proline content in C. bungeana plantlets under chilling stress. These findings suggest that Clavibacter sp. strain Enf12 inoculation stimulates the growth of C. bungeana plantlets and improves their tolerance to chilling stress through enhancing the antioxidant defense system.

The catalytic efficiency of trehalose-6-phosphate synthase is effected by the N-loop at low temperatures.

The enzyme OtsA (trehalose-6-phosphate synthase) is ubiquitous in both prokaryotic and eukaryotic organisms, where it plays a critical role in stress resistance and glucose metabolism. Here, we cloned the otsA gene from Arthrobacter sp. Cjts, and expressed and then purified the recombinant proteins. Enzyme activity analysis indicated that the high catalytic efficiency of OtsA from Arthrobacter sp. Cjts resulted from the high affinity of the enzyme for uridine 5'-diphosphoglucose (UDP-Glc) at low temperatures. We also confirmed that the N-loop sequence of OtsA has a large effect on its affinity for UDP-Glc. Sequence analysis indicated that the flexibility of the N-loop may be directly related to the catalytic efficiency of OtsA at low temperatures.