Kaistella yananensis sp. nov., a Novel Indoleacetic Acid-Producing Bacterium Isolated from the Root Nodules of Sophora davidii (Franch.) Skeels.

A novel endophytic bacterium, designated strain BT6-1-3T, was isolated from the root nodules of a leguminous shrub named Sophora davidii (Franch.) Skeels, found growing wild in Yan'an, Shaanxi Province, China. Cells were Gram-staining-negative, non-motile, catalase-positive, oxidase-positive, and did not produce H2S. Strain BT6-1-3T grew at 15-40 °C (optimum 30 °C), at pH 6.0-10.0 (optimum pH 9.0), and with 0-1% (w/v) NaCl (optimum 0.5%). The quinone system was menaquinone 6. The major fatty acids present in BT6-1-3T were iso-C11:0, iso-C15:0, and C16:0. The G+C content of genomic DNA was 39.4 mol% by whole genome sequencing. According to the analysis of 16S rRNA gene sequence, the closest relative was Kaistella montana WG4 (nucleotide identity was 97.6%). The genome of strain BT6-1-3T was sequenced, and the genome similarity was calculated using average nucleotide identity and genome-to-genome distance analysis with the genomes of other strains of Kaistella. Both strongly supported that the strain BT6-1-3T belonged to the genus Kaistella as a representative of a new species. Based on phylogenetic analysis, chemotaxonomic data, and physiological and biochemical characteristics, strain BT6-1-3T represents a new species of the genus Kaistella and is named as Kaistella yananensis sp. nov. Type strain is BT6-1-3T (= NBRC 115452T = CGMCC 1.60032T).

Xanthomonas chitinilytica sp. nov., a novel chitinolytic bacterium isolated from a microbial fermentation bed material.

A Gram-stain-negative bacterium, H13-6T, was isolated from a microbial fermentation bed material collected from a pig farm located in Yan'an, Shaanxi, China. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain H13-6T was affiliated with the genus Xanthomonas and showed highest similarity to strain Xanthomonas maliensis M97T (98.38%), Xanthomonas prunicola CFBP 8353T (98.26%) and Xanthomonas oryzae ATCC 35933T (98.11%). The pairwise ortho Average Nucleotide Identity values and the digital DNA-DNA hybridization values between strain H13-6T and the other Xanthomonas species were all below their respective cut-offs. Two genes encoding for chitinase were found and the strain showed a strong chitin-degrading activity. The major fatty acids were Iso-C15:0 (55.9%), Antesio-C15:0 (7.4%) and Iso-C11:0 (5.5%) and the major polar lipids were diphosphatidylglycerol, phosphatidyglycerol and phosphatidylethanolamine. Based on the phenotypic properties and phylogenetic distinctiveness, Xanthomonas chitinilytica was proposed as a novel species of the genus Xanthomonas, with strain H13-6T (= CGMCC 1.61317T = NBRC 115641T) as type strain.

Nodule-associated diazotrophic community succession is driven by developmental phases combined with microhabitat of Sophora davidii.

Nodule-associated nitrogen-fixing microorganisms (diazotrophs) residing in legume root nodules, and they have the potential to enhance legume survival. However, the succession characteristics and mechanisms of leguminous diazotrophic communities remain largely unexplored. We performed a high-throughput nifH amplicon sequencing with samples of root nodules and soil in the three developmental phases (young nodules, active nodules and senescent nodules) of the Sophora davidii (Franch.) Skeels root nodules, aiming to investigate the dynamics of nodule-endophytic diazotrophs during three developmental phases of root nodules. The results demonstrated the presence of diverse diazotrophic bacteria and successional community shifting dominated by Mesorhizobium and Bradyrhizobium inside the nodule according to the nodule development. The relative abundance decreased for Mesorhizobium, while decreased first and then increased for Bradyrhizobium in nodule development from young to active to senescent. Additionally, strains M. amorphae BT-30 and B. diazoefficiens B-26 were isolated and selected to test the interaction between them in co-cultured conditions. Under co-culture conditions: B. diazoefficiens B-26 significantly inhibited the growth of M. amorphae BT-30. Intriguingly, growth of B. diazoefficiens B-26 was significantly promoted by co'culture with M. amorphae BT-30 and could utilize some carbon and nitrogen sources that M. amorphae BT-30 could not. Additionally, the composition of microbial community varied in root nodules, in rhizosphere and in bulk soil. Collectively, our study highlights that developmental phases of nodules and the host microhabitat were the key driving factors for the succession of nodule-associated diazotrophic community.

Microbial community succession during crude oil-degrading bacterial enrichment cultivation and construction of a degrading consortium.

Microbial community succession during the enrichment of crude-oil-degrading bacteria was analyzed using Illumina high-throughput sequencing to guide bacterial isolation and construction of a bacterial consortium. Community change occurred in 6 days; the most abundant phylum changed from Proteobacteria to Actinobacteria; the most abundant genera were Dietzia and unspecified_Idiomarinaceae. Two crude oil-degrading strains, Rhodococcus sp. OS62-1 and Dietzia sp. OS33, and one weak-crude-oil-degrading strain, Pseudomonas sp. P35, were isolated. A consortium comprising Rhodococcus sp. OS62-1 and Pseudomonas sp. P35 showed the highest crude-oil-degrading efficiency, reaching 85.72 ± 3.21% within 7 days, over a wide pH range (5-11) and salinity (0-80 g·L-1). Consumption of saturated hydrocarbons, aromatic hydrocarbons, and resins was greater by the consortium than by a single strain, as was degradation of short-chain-alkanes (C13-C17) according to gas-chromatography. The bacterial consortium provides technical support for bioremediation of crude oil pollution.

Comparative analysis of the efficacies of probiotic supplementation and glucose-lowering drugs for the treatment of type 2 diabetes: A systematic review and meta-analysis.

The aim of this systematic review and meta-analysis was to evaluate the effects of probiotics and glucose-lowering drugs (thiazolidinedione [TZD], glucagon-like pep-tide-1 receptor agonists [GLP-1 RA], dipeptidyl peptidase IV inhibitors, and sodium glucose co-transporter 2 inhibitors [SGLT-2i]) in patients with type 2 diabetes from randomized con-trolled trials (RCTs). The PubMed, Web of science, Embase, and Cochrane Library databases were searched on the treatment effects of probiotics and glucose-lowering drugs on glycemia, lipids, and blood pressure metabolism published between Jan 2015 and April 2021. We performed meta-analyses using the random-effects model. We included 25 RCTs (2,843 participants). Overall, GLP-1RA, SGLT-2i, and TZD significantly reduce fasting blood sugar (FBS) and glycated hemoglobin (HbA1c), whereas GLP-1 RA increased the risk of hypoglycaemia. Multispecies probiotics decrease FBS, total cholesterol (TC), and systolic and diastolic blood pressure (SBP, DBP). Moreover, subgroup analyses indicated that participants aged >55 years, BMI ≥30 kg/m2, longer duration of intervention, and subjects from Eastern countries, showed significantly higher reduction in FBS and HbA1c, TC, TG and SBP. This meta-analysis revealed that including multiple probiotic rather than glucose-lowering drugs might be more beneficial regarding T2D prevention who suffering from simultaneously hyperglycemia, hypercholesterolemia, and hypertension.

Rhodococcus yananensis sp. nov., a novel denitrification actinobacterium isolated from microbial fermentation bed material from a pig farm.

An opaque, pink-coloured, gram-positive, aerobic bacteria (designated as FBM22-1T), was isolated from microbial fermentation bed material from a pig farm in northwestern China. Optimal growth occurred at 30-37 °C, pH 7.0 and with 0.5 % NaCl (w/v). The strain had nitrification and denitrification functions. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the novel isolate belonged to the genus Rhodococcus. Strain FBM22-1T was closely related to Rhodococcus zopfii NBRC 100606T and Rhodococcus rhodochrous NBRC 16069T, with 16S rRNA gene sequence similarities of 97.9 and 97.7 %, respectively. The predominant menaquinone in strain FBM22-1T was MK-8(H2). The cellular fatty acids consisted primarily of C16 : 1ω7c and/or C16 : 1 ω6c, C16 : 0 and 10-methyl C18 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and glycolipid. The G+C content of strain FBM22-1T was 68.64 mol%. Based on the phenotypic, phylogenetic and chemotaxonomic characterization results, in combination with low values of digital DNA-DNA hybridization between strain FBM22-1T and its closest neighbours, FBM22-1T represents a novel species of the genus Rhodococcus, for which the name Rhodococcus yananensis sp. nov. is proposed; the type strain is FBM22-1T (=KCTC 49502T=CCTCC AB2020275T).

Sphingopyxis yananensis sp. nov., a novel 2-nitropropane degrading bacterium isolated from a microbial fermentation bed substrate.

A rod-shaped, Gram-negative staining strain, FBM22T, was isolated from a microbial fermentation bed substrate from a pig farm. Its colonies appeared yellow and were 0.5-1.2 mm in diameter. Cells were 0.3-0.5 µm wide, 0.5-0.83 µm long. Optimal growth occurred at 30 °C and pH 7.0-8.0; NaCl was not required for growth. The strain performed denitrification and nitrate reduction functions. And it could produce catalase. FBM22-1T utilized the following organic substrates for growth: tyrosine, glutamic acid, D-glucose, and galactose. The novel isolate could degrade 2-nitropropane as carbon and nitrogen source. The dominant respiratory quinone was Q-10. The major polar lipids were diphosphatidylglycerol, phosphatidylcholine and phosphatidylethanolamine. C18:1 ω7c, C16:1 ω7c and/ or C16:1 ω6c, and C14:0 2-OH were the major (≥ 8%) fatty acids. The G+C content was 56.8 mol%. FBM22T was found to be a member of the genus Sphingopyxis in the family Sphingomonadaceae of the class Alphaproteobacteria. It had the highest sequence similarity with the type strains Sphingopyxis terrae subsp. ummariensis UI2T (96.47%) and Sphingopyxis terrae subsp. terrae NBRC 15098T (96.40%). Furthermore, FBM22T had 18.7% and 18.4% relatedness (based on digital DNA-DNA hybridization) with its two relatives (S. terrae subsp. ummariensis UI2T and S. terrae subsp. terrae NBRC 15098T). The morphological, physiological, and genotypic differences identified in this study support the classification of FBM22T as a novel species within the genus Sphingopyxis, for which the name Sphingopyxis yananensis sp. nov. is proposed. The type strain is FBM22T (= KCTC 82290T = CCTC AB2020286T).

Petroleum Depletion Property and Microbial Community Shift After Bioremediation Using Bacillus halotolerans T-04 and Bacillus cereus 1-1.

Bioremediation of crude oil contaminated environments is an economical, low-maintenance, environmentally friendly technology and has attracted increasing attention in recent years. In the present study, two efficient crude oil degrading bacteria strains were isolated from soils contaminated with crude oil. Phylogenetic analysis suggested they belonged to genus Bacillus, and were designated as Bacillus cereus T-04 and Bacillus halotolerans 1-1. The crude oil depletion of each strain under different conditions was tested. The optimum conditions for both strains' oil degradation was pH 7, 15-20 g/L NaCl concentration, and 5-15 g/L original oil concentration. The crude oil depletion rate could reach to 60-80% after 20 days of treatment. The crude oil bioremediation simulation tests revealed that the bioremediation promoted the depletion of crude oil to a large extent. The inoculum group with inorganic medium showed the highest crude oil depletion (97.5%) while the crude oil depletion of control group was only 26.6% after 180 days of treatment. High-throughput sequencing was used to monitor the changes of microbial community using different treatments. In all groups, Actinobacteria, Proteobacteria, Firmicutes and Bacteroidetes were the dominant phyla. After contaminated with crude oil, the relative abundance of phylum Actinobacteria was dramatically increased and occupied 81.8%. Meanwhile although strains of Bacillus were added in the bioaugmentation groups, the relative abundance of genus Bacillus was not the most abundant genus at the end of simulation tests. The crude oil contamination dramatically decreased the soil microbial diversity and bioremediation could not recover the microbial community in the short term.

One Biosurfactant-Producing Bacteria Achromobacter sp. A-8 and Its Potential Use in Microbial Enhanced Oil Recovery and Bioremediation.

Biosurfactant plays an important role in bioremediation of crude oil contamination and microbial enhanced oil recovery (MEOR). In the present study, a salt-tolerant, biosurfactant-producing bacterium, designated A-8, was isolated from wastewater contaminated with petroleum collected from the Changqing reservoir in China. A phylogenetic analysis based on the 16S rRNA sequence suggests that strain A-8 belongs to the genus Achromobacter. The optimal growth conditions for strain A-8 in mineral salt (MS) medium were 30°C, pH 7, and 10 g/L NaCl, while the optimal conditions for biosurfactant production in a fermentation medium were 40-45°C, pH 7, and more than 70 g/L NaCl. Better biosurfactant production was obtained from strain A-8 when edible oil and liquid paraffin were used as carbon sources and when (NH4)2SO4 was used as an inorganic nitrogen source compared with other tested carbon and nitrogen sources. The biodegradation of petroleum in MS medium in different optimized conditions reached 56.23-73.87% for 20 days. The biodegradation of petroleum, together with the production of organic acid and biosurfactant, decreased the viscosity of petroleum by about 45%. The decrease in petroleum viscosity and the biodegradation of petroleum suggest the potential use of strain A-8 for MEOR and bioremediation of petroleum-contaminated environments.

The complete mitogenome sequence of the coral lily (Lilium pumilum) and the Lanzhou lily (Lilium davidii) in China.

BACKGROUND: The mitogenomes of higher plants are conserved. This study was performed to complete the mitogenome of two China Lilium species (Lilium pumilum Redouté and Lilium davidii var. unicolor (Hoog) cotton). METHODS: Genomic DNA was separately extracted from the leaves of L. pumilum and L. davidii in triplicate and used for sequencing. The mitogenome of Allium cepa was used as a reference. Genome assembly, annotation and phylogenetic tree were analyzed. RESULTS: The mitogenome of L. pumilum and L. davidii was 988,986 bp and 924,401 bp in length, respectively. There were 22 core protein-coding genes (including atp1, atp4, atp6, atp9, ccmB, ccmC, ccmFc, ccmFN1, ccmFN2, cob, cox3, matR, mttB, nad1, nad2, nad3, nad4, nad4L, nad5, nad6, nad7 and nad9), one open reading frame and one ribosomal protein-coding gene (rps12) in the mitogenomes. Compared with the A. cepa mitogenome, the coding sequence of the 24 genes and intergenic spacers in L. pumilum and L. davidii mitogenome contained 1,621 and 1,617 variable sites, respectively. In the phylogenetic tree, L. pumilum and L. davidii were distinct from A. cepa (NC_030100). CONCLUSIONS: L. pumilum and L. davidii mitogenomes have far distances from other plants. This study provided additional information on the species resources of China Lilium.

Insights into non-symbiotic plant growth promotion bacteria associated with nodules of Sphaerophysa salsula growing in northwestern China.

In addition to rhizobia, other non-symbiotic endophytic bacteria also have been simultaneously isolated from the same root nodules. The existence of non-symbiotic endophytic bacteria in leguminous root nodules is a universal phenomenon. The vast majority of studies have detected endophytic bacteria in other plant tissues. In contrast, little systemic observation has been made on the non-symbiotic endophytic bacteria within leguminous root nodules. The present investigation was carried out to isolate plant growth-promoting endophytic non-symbiotic bacteria from indigenous leguminous Sphaerophysa salsula and their influence on plant growth. A total of 65 endophytic root nodule-associated bacteria were isolated from indigenous legume S. salsula growing in the northwestern arid regions of China. When combining our previous work with the current study, sequence analysis of the nifH gene revealed that the strain belonging to non-nodulating Bacillus pumilus Qtx-10 had genes similar to those of Rhizobium leguminosarum Qtx-10-1. The results indicated that horizontal gene transfer could have occurred between rhizobia and non-symbiotic endophyties. Under pot culture conditions, out of the 20 representative endophytic isolates, 15 with plant growth-promoting traits, such as IAA production, ACC deaminase, phosphate solubilization, chitinase, siderophore, and fungal inhibition activity showed plant growth-promoting activity with respect to various plant parameters such as chlorophyll content, fresh weight of plant, shoot length, nodule number per plant and average nodule weight per plant when co-inoculated with rhizobial bioinoculant Mesorhizobium sp. Zw-19 under N-free culture conditions. Among them, Bacillus pumilus Qtx-10 and Streptomyces bottropensis Gt-10 were excellent plant growth-promoting bacteria, which enhanced the seeding fresh weight by 87.5% and the shoot length by 89.4%, respectively. The number of nodules grew more than 31.89% under field conditions. Our findings indicate the frequent presence of these non-symbiotic endophytic bacteria within root nodules, and that they help to improve nodulation and nitrogen fixation in legume plants through synergistic interactions with rhizobia.

The Root Endophytic Fungi Community Structure of Pennisetum sinese from Four Representative Provinces in China.

Pennisetum sinese is a good forage grass with high biomass production and crude proteins. However, little is known about the endophytic fungi diversity of P. sinese, which might play an important role in the plant's growth and biomass production. Here, we used high throughput sequencing of the Internal Transcribed Spacer (ITS) sequences based on primers ITS5-1737 and ITS2-2043R to investigate the endophytic fungi diversity of P. sinese roots at the maturity stage, as collected from four provinces (Shaanxi province, SX; Fujian province, FJ; the Xinjiang Uyghur autonomous prefecture, XJ and Inner Mongolia, including sand (NS) and saline-alkali land (NY), China). The ITS sequences were processed using QIIME and R software. A total of 374,875 effective tags were obtained, and 708 operational taxonomic units (OTUs) were yielded with 97% identity in the five samples. Ascomycota and Basidiomycota were the two dominant phyla in the five samples, and the genera Khuskia and Heydenia were the most abundant in the FJ and XJ samples, respectively, while the most abundant tags in the other three samples could not be annotated at the genus level. In addition, our study revealed that the FJ sample possessed the highest OTU numbers (242) and the NS sample had the lowest (86). Moreover, only 22 OTUs were present in all samples simultaneously. The beta diversity analysis suggested a division of two endophytic fungi groups: the FJ sample from the south of China and the other four samples from north or northwest China. Correlation analysis between the environmental factors and endophytic fungi at the class level revealed that Sordariomycetes and Pucciniomycetes had extremely significant positive correlations with the total carbon, annual average precipitation, and annual average temperature, while Leotiomycetes showed an extremely significant negative correlation with quick acting potassium. The results revealed significant differences in the root endophytic fungi diversity of P. sinese in different provinces and might be useful for growth promotion and biomass production in the future.

Root-Associated Endophytic Bacterial Community Composition of Pennisetum sinese from Four Representative Provinces in China.

Pennisetum sinese, a source of bio-energy with high biomass production, is a species that contains high crude protein and will be useful for solving the shortage of forage grass after the implementation of "Green for Grain" project in the Loess plateau of Northern Shaanxi in 1999. Plants may receive benefits from endophytic bacteria, such as the enhancement of plant growth or the reduction of plant stress. However, the composition of the endophytic bacterial community associated with the roots of P. sinese is poorly elucidated. In this study, P. sinese from five different samples (Shaanxi province, SX; Fujian province, FJ; the Xinjiang Uyghur autonomous prefecture, XJ and Inner Mongolia, including sand (NS) and saline-alkali land (NY), China) were investigated by high-throughput next-generation sequencing of the 16S rDNA V3-V4 hypervariable region of endophytic bacteria. A total of 313,044 effective sequences were obtained by sequencing five different samples, and 957 effective operational taxonomic units (OTUs) were yielded at 97% identity. The phylum Proteobacteria, the classes Gammaproteobacteria and Alphaproteobacteria, and the genera Pantoea, Pseudomonas, Burkholderia, Arthrobacter, Psychrobacter, and Neokomagataea were significantly dominant in the five samples. In addition, our results demonstrated that the Shaanxi province (SX) sample had the highest Shannon index values (3.795). We found that the SX (308.097) and NS (126.240) samples had the highest and lowest Chao1 richness estimator (Chao1) values, respectively. Venn graphs indicated that the five samples shared 39 common OTUs. Moreover, according to results of the canonical correlation analysis (CCA), soil total carbon, total nitrogen, effective phosphorus, and pH were the major contributing factors to the difference in the overall composition of the bacteria community in this study. Our data provide insights into the endophytic bacteria community composition and structure of roots associated with P. sinese. These results might be useful for growth promotion in different samples, and some of the strains may have the potential to improve plant production in future studies.

Screening and characterization of endophytic Bacillus and Paenibacillus strains from medicinal plant Lonicera japonica for use as potential plant growth promoters.

A total of 48 endophytic bacteria were isolated from surface-sterilized tissues of the medicinal plant Lonicera japonica, which is grown in eastern China; six strains were selected for further study based on their potential ability to promote plant growth in vitro (siderophore and indoleacetic acid production). The bacteria were characterized by phylogenetically analyzing their 16S rRNA gene similarity, by examining their effect on the mycelial development of pathogenic fungi, by testing their potential plant growth-promoting characteristics, and by measuring wheat growth parameters after inoculation. Results showed that the number of endophytic bacteria in L. japonica varied among different tissues, but it remained relatively stable in the same tissues from four different plantation locations. Among the three endophytic strains, strains 122 and 124 both had high siderophore production, with the latter showing the highest phosphate solubilization activity (45.6 mg/L) and aminocyclopropane-1-carboxylic acid deaminase activity (47.3 nmol/mg/h). Strain 170 had the highest indoleacetic acid (IAA) production (49.2 mg/L) and cellulase and pectinase activities. After inoculation, most of the six selected isolates showed a strong capacity to promote wheat growth. Compared with the controls, the increase in the shoot length, root length, fresh weight, dry weight, and chlorophyll content was most remarkable in wheat seedlings inoculated with strain 130. The positive correlation between enzyme (cellulose and pectinase) activity and inhibition rate on Fusarium oxysporum, the IAA production, and the root length of wheat seedlings inoculated with each tested endophytic strain was significant in regression analysis. Deformity of pathogenic fungal mycelia was observed under a microscope after the interaction with the endophytic isolates. Such deformity may be directly related to the production of hydrolytic bacterial enzymes (cellulose and pectinase). The six endophytic bacterial strains were identified to be Paenibacillus and Bacillus strains based on the results of 16S rRNA gene sequencing analysis and their physiological and biochemical characteristics. Results indicate the promising application of endophytic bacteria to the biological control of pathogenic fungi and the improvement of wheat crop growth.

Screening and characterization of endophytic Bacillus and Paenibacillus strains from medicinal plant Lonicera japonica for use as potential plant growth promoters

Abstract A total of 48 endophytic bacteria were isolated from surface-sterilized tissues of the medicinal plant Lonicera japonica, which is grown in eastern China; six strains were selected for further study based on their potential ability to promote plant growth in vitro (siderophore and indoleacetic acid production). The bacteria were characterized by phylogenetically analyzing their 16S rRNA gene similarity, by examining their effect on the mycelial development of pathogenic fungi, by testing their potential plant growth-promoting characteristics, and by measuring wheat growth parameters after inoculation. Results showed that the number of endophytic bacteria in L. japonica varied among different tissues, but it remained relatively stable in the same tissues from four different plantation locations. Among the three endophytic strains, strains 122 and 124 both had high siderophore production, with the latter showing the highest phosphate solubilization activity (45.6 mg/L) and aminocyclopropane-1-carboxylic acid deaminase activity (47.3 nmol/mg/h). Strain 170 had the highest indoleacetic acid (IAA) production (49.2 mg/L) and cellulase and pectinase activities. After inoculation, most of the six selected isolates showed a strong capacity to promote wheat growth. Compared with the controls, the increase in the shoot length, root length, fresh weight, dry weight, and chlorophyll content was most remarkable in wheat seedlings inoculated with strain 130. The positive correlation between enzyme (cellulose and pectinase) activity and inhibition rate on Fusarium oxysporum, the IAA production, and the root length of wheat seedlings inoculated with each tested endophytic strain was significant in regression analysis. Deformity of pathogenic fungal mycelia was observed under a microscope after the interaction with the endophytic isolates. Such deformity may be directly related to the production of hydrolytic bacterial enzymes (cellulose and pectinase). The six endophytic bacterial strains were identified to be Paenibacillus and Bacillus strains based on the results of 16S rRNA gene sequencing analysis and their physiological and biochemical characteristics. Results indicate the promising application of endophytic bacteria to the biological control of pathogenic fungi and the improvement of wheat crop growth.

Rhizobial symbiosis effect on the growth, metal uptake, and antioxidant responses of Medicago lupulina under copper stress.

The effects of rhizobial symbiosis on the growth, metal uptake, and antioxidant responses of Medicago lupulina in the presence of 200 mg kg(-1) Cu(2+) throughout different stages of symbiosis development were studied. The symbiosis with Sinorhizobium meliloti CCNWSX0020 induced an increase in plant growth and nitrogen content irrespective of the presence of Cu(2+). The total amount of Cu uptake of inoculated plants significantly increased by 34.0 and 120.4% in shoots and roots, respectively, compared with non-inoculated plants. However, although the rhizobial symbiosis promoted Cu accumulation both in shoots and roots, the increase in roots was much higher than in shoots, thus decreasing the translocation factor and helping Cu phytostabilization. The rate of lipid peroxidation was significantly decreased in both shoots and roots of inoculated vs. non-inoculated plants when measured either 8, 13, or 18 days post-inoculation. In comparison with non-inoculated plants, the activities of superoxide dismutase and ascorbate peroxidase of shoots of inoculated plants exposed to excess Cu were significantly elevated at different stages of symbiosis development; similar increases occurred in the activities of superoxide dismutase, catalase, and glutathione reductase of inoculated roots. The symbiosis with S. meliloti CCNWSX0020 also upregulated the corresponding genes involved in antioxidant responses in the plants treated with excess Cu. The results indicated that the rhizobial symbiosis with S. meliloti CCNWSX0020 not only enhanced plant growth and metal uptake but also improved the responses of plant antioxidant defense to excess Cu stress.

Identification and characterization of the endophytic plant growth prompter Bacillus Cereus strain mq23 isolated from Sophora Alopecuroides root nodules

Endophytes MQ23 and MQ23R isolated from Sophora alopecuroides root nodules were characterized by observing their ability to promote plant growth and employing molecular analysis techniques. Results showed that MQ23 and MQ23R are potential N2-fixing endophytes and belong to the same species as Bacillus cereus. MQ23 was shown to be able to produce siderophores, IAA, and demonstrate certain antifungal activity to plant pathogenic fungi. Co-inoculation with MQ23+MQ23II showed a more significant effect than inoculation alone in vitro for most of positive actions suggesting they have a cooperative interaction. Results of plant inoculation with endophytes indicated that the growth indexes of co-inoculated MQ23+MQ23II were higher than those of inoculated alone (p<0.05) (the exception being for root fresh weight) when compared to negative control. There have been little of any studies of nonrhizobial putative endophytes with growth-promotion attributes in S. alopecuroides root nodules. This could be exploited as potential bio-inoculants and biocontrol agents in agriculture.

Paracoccus sphaerophysae sp. nov., a siderophore-producing, endophytic bacterium isolated from root nodules of Sphaerophysa salsula.

An aerobic, brown-pigmented, non-spore-forming, endophytic bacterium, designated strain Zy-3(T), was isolated from root nodules of Sphaerophysa salsula, a native leguminous herb belonging to the family Leguminosae growing in north-western China. Cells of strain Zy-3(T) were non-motile, Gram-negative rods. Strain Zy-3(T) produced siderophores and showed antifungal activity. Phylogenetic analysis of the 16S rRNA gene sequence indicated that the closest relative of this organism was Paracoccus halophilus HN-182(T) (96.6 % sequence similarity). On the basis of genotype, fatty acid patterns and physiological characteristics, a novel species Paracoccus sphaerophysae sp. nov. is proposed, with Zy-3(T) (=ACCC 05413(T) =HAMBI 3106(T)) as the type strain.

Identification and characterization of the endophytic plant growth prompter Bacillus Cereus strain mq23 isolated from Sophora Alopecuroides root nodules.

Endophytes MQ23 and MQ23R isolated from Sophora alopecuroides root nodules were characterized by observing their ability to promote plant growth and employing molecular analysis techniques. Results showed that MQ23 and MQ23R are potential N2-fixing endophytes and belong to the same species as Bacillus cereus. MQ23 was shown to be able to produce siderophores, IAA, and demonstrate certain antifungal activity to plant pathogenic fungi. Co-inoculation with MQ23+MQ23II showed a more significant effect than inoculation alone in vitro for most of positive actions suggesting they have a cooperative interaction. Results of plant inoculation with endophytes indicated that the growth indexes of co-inoculated MQ23+MQ23II were higher than those of inoculated alone (p<0.05) (the exception being for root fresh weight) when compared to negative control. There have been little of any studies of nonrhizobial putative endophytes with growth-promotion attributes in S. alopecuroides root nodules. This could be exploited as potential bio-inoculants and biocontrol agents in agriculture.

Diverse rhizobia associated with Sophora alopecuroides grown in different regions of Loess Plateau in China.

A total of seventy-five symbiotic bacterial strains isolated from root nodules of wild Sophora alopecuroides grown in different regions of China's Loess Plateau were characterized. Based on the combined RFLP patterns, thirty-five genotypes were defined among the rhizobia and they were classified into nine genomic species, including Mesorhizobium alhagi and M. gobiense as the main groups, as well as Agrobacterium tumefaciens, M. amorphae, Phyllobacterium trifolii, Rhizobium giardinii, R. indigoferae, Sinorhizobium fredii and S. meliloti as the minor groups according to the 16S rRNA and recA gene analyses. Five and three lineages of nodA and nifH were found, respectively, in these strains, implying that the symbiotic genes of the S. alopecuroides rhizobia had different origins or had divergently evolved. Results of correspondence analysis showed that there was a correlation between rhizobial genotypes and the geographic origins. Possible lateral transfer of the recA and 16S rRNA genes between the P. trifolii and A. tumefaciens strains, and that of symbiotic genes (nodA, nifH) between different genera, was shown by discrepancies of the phylogenetic relationships of the four gene loci. These results revealed diverse rhizobia associated with wild S. alopecuroides grown in different regions of China's Loess Plateau, and demonstrated for the first time the existence of symbiotic A. tumefaciens strains in root nodules of S. alopecuroides.