Synergistic anti-oxidative effects of Pongamia pinnata against nickel mediated by Rhizobium pisi and Ochrobacterium pseudogrignonense.

Nickel is widely spread by different anthropogenic activities and shows toxicity for plant growth and development. Whether rhizobia symbiotically fix nitrogen can eliminate or reduce nickel toxic effect on plant or not is still unknown. This study was aimed to investigate the effect of different rhizobia genus inoculation on growth, nitrogen fixing ability, metal accumulation and enzymatic antioxidative balance of Pongamia pinnnaa. Inoculation with Rhizobium pisi and Ochrobacterium pseudogrignonense increased the all the growth parameters both in 0 and 40 mg/kg nickel as comparison with control. Only shoot length increased in presence of nitrogen as compared with no supply of nitrogen. Nitrogen content also increased both in rhizobia inoculation as compared to no nitrogen supply and non-inoculation control, respectively. Nickel uptake was higher in shoots and leaves but lower in roots in case of inoculation as compared to non-inoculation control. Rhizobia inoculation improved the plant antioxidant capacity by increasing the activity of enzymatic scavengers catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and ascorbate (GR). However, 40 mg/kg of nickel adding showed mostly effect on the activity CAT, SOD, POD in leaves. All the enzymatic activity showed a significant increase in absence of nitrogen supply as compared nitrogen supply. Our results suggested that rhizobia inoculation effectively mediated nickel stress for legume plants by increasing nitrogen supplement and inducing antioxidant capacity.

Bioremediation assessment of diesel-biodiesel-contaminated soil using an alternative bioaugmentation strategy.

This study investigated the effectiveness of successive bioaugmentation, conventional bioaugmentation, and biostimulation of biodegradation of B10 in soil. In addition, the structure of the soil microbial community was assessed by polymerase chain reaction-denaturing gradient gel electrophoresis. The consortium was inoculated on the initial and the 11th day of incubation for successive bioaugmentation and only on the initial day for bioaugmentation and conventional bioaugmentation. The experiment was conducted for 32 days. The microbial consortium was identified based on sequencing of 16S rRNA gene and consisted as Pseudomonas aeruginosa, Achromobacter xylosoxidans, and Ochrobactrum intermedium. Nutrient introduction (biostimulation) promoted a positive effect on microbial populations. The results indicate that the edaphic community structure and dynamics were different according to the treatments employed. CO2 evolution demonstrated no significant difference in soil microbial activity between biostimulation and bioaugmentation treatments. The total petroleum hydrocarbon (TPH) analysis indicated a biodegradation level of 35.7 and 32.2 % for the biostimulation and successive bioaugmentation treatments, respectively. Successive bioaugmentation displayed positive effects on biodegradation, with a substantial reduction in TPH levels.

Paenochrobactrum gallinarii gen. nov., sp. nov., isolated from air of a duck barn, and reclassification of Pseudochrobactrum glaciei as Paenochrobactrum glaciei comb. nov.

A Gram-negative, rod-shaped, oxidase-positive, non-spore-forming, non-motile bacterium (Sa25(T)) was isolated from air of a duck barn. 16S rRNA gene and recA sequence analyses clearly placed the isolate in the vicinity of the Brucella-Ochrobactrum-Pseudochrobactrum group, with the closest relative being Pseudochrobactrum glaciei KMM 3858(T). This allocation was confirmed by analyses of the quinone system (ubiquinone Q-10), fatty acid data (major fatty acids C(18 : 1)omega7c and C(19 : 0) cyclo omega8c) and polar lipid profile (major components diphosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and unknown aminolipid AL1; moderate amounts of three unknown polar lipids, L1-L3, an unknown aminolipid and an unknown aminophospholipid APL2). The polyamine pattern of Sa25(T) exhibited the major compound putrescine and moderate amounts of spermidine; a similar polyamine pattern with the major compound putrescine was also detected in Pseudochrobactrum glaciei KMM 3858(T). DNA-DNA hybridization of strain Sa25(T) with Pseudochrobactrum glaciei KMM 3858(T) and the type strains of the other Pseudochrobactrum species showed values ranging from 50.3 to 24.8 %, and physiological and biochemical data clearly differentiated this isolate from the described Pseudochrobactrum species. Since Sa25(T) and Pseudochrobactrum glaciei KMM 3858(T) form a distinct lineage in the 16S rRNA gene sequence-based phylogenetic tree, and this separate position is supported by unique characteristics of their polyamine patterns and polar lipid profiles, we propose the novel genus Paenochrobactrum gen. nov., with the type species Paenochrobactrum gallinarii sp. nov. (type strain Sa25(T) =CCUG 57736(T) =CCM 7656(T)) and the reclassification of Pseudochrobactrum glaciei as Paenochrobactrum glaciei comb. nov. (type strain Pi26(T) =KMM 3858(T) =NRIC 0733(T) =JCM 15115(T)).

The brucellae and their success as pathogens.

Brucellae are tiny, aerobic, slow growing, catalase and oxidase positive Gram negative coccobacilli or small rods, which may reach man through exposure to tissues of mammalian hosts via cuts or aerosols, or as food infections mostly through dairy products. As parasites brucellae are extraordinarily successful, causing very long-lasting infections in all mammalian social animals, such as ungulates, canids, and rodents; recently they have been found to also cause disease in pinnipeds and cetaceans. Brucellae as members of the alpha Proteobacteria, have suffered major losses of genomic material as they adapted to their facultative intracellular parasite role, and are able to initiate infection with minimal disturbance of the innate immune system, thus reaching a privileged intracellular niche where they multiply. Brucellae are likely to be among the toughest organisms to control through public health and agricultural policies, even involving detection-slaughter strategies.

Description of Pseudochrobactrum kiredjianiae sp. nov.

A Gram-negative, rod-shaped, oxidase-positive, non-spore-forming, non-motile bacterium (strain CCUG 49584(T)), isolated from a seafood processing plant sample in New Zealand, was subjected to a polyphasic taxonomic study. On the basis of 16S rRNA and recA gene sequence similarities, the isolate was allocated to the genus Pseudochrobactrum. This was confirmed by fatty acid data (major fatty acids: C(18 : 1)omega7c and C(19 : 0) cyclo omega8c), a polar lipid profile exhibiting major characteristics of Pseudochrobactrum (phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine), quinone system Q-10 and a polyamine pattern with the predominant compounds spermidine and putrescine. DNA-DNA hybridization with the type strains of the two established species of Pseudochrobactrum and physiological and biochemical data clearly differentiated the isolate from established Pseudochrobactrum species. As a consequence, this organism represents a novel species, for which the name Pseudochrobactrum kiredjianiae sp. nov. is proposed, with the type strain CCUG 49584(T) (=CIP 109227(T)).

Adaptation of the Brucellae to their intracellular niche.

Members of the bacterial genus Brucella are facultative intracellular pathogens that reside predominantly within membrane-bound compartments within two host cell types, macrophages and placental trophoblasts. Within macrophages, the brucellae route themselves to an intracellular compartment that is favourable for survival and replication, and they also appear to be well-adapted from a physiological standpoint to withstand the environmental conditions encountered during prolonged residence in this intracellular niche. Much less is known about the interactions of the Brucella with placental trophoblasts, but experimental evidence suggests that these bacteria use an iron acquisition system to support extensive intracellular replication within these host cells that is not required for survival and replication in host macrophages. Thus, it appears that the brucellae rely upon the products of distinct subsets of genes to adapt successfully to the environmental conditions encountered within the two cell types within which they reside in their mammalian hosts.