Characterization of plant growth-promoting traits of bacteria isolated from larval guts of diamondback moth Plutella xylostella (lepidoptera: plutellidae).
ABSTRACT Eight bacterial isolates from the larval guts of Diamondback moths (Plutella xylostella) were tested for their plant growth-promoting (PGP) traits and effects on early plant growth. All of the strains tested positive for nitrogen fixation and indole 3-acetic acid (IAA) and salicylic acid production but negative for hydrogen cyanide and pectinase production. In addition, five of the isolates exhibited significant levels of tricalcium phosphate and zinc oxide solubilization; six isolates were able to oxidize sulfur in growth media; and four isolates tested positive for chitinase and beta-1,3-glucanase activities. Based on their IAA production, six strains including four that were 1-aminocyclopropane-1-carboxylate (ACC) deaminase positive and two that were ACC deaminase negative were tested for PGP activity on the early growth of canola and tomato seeds under gnotobiotic conditions. Acinetobacter sp. PSGB04 significantly increased root length (41%), seedling vigor, and dry biomass (30%) of the canola test plants, whereas Pseudomonas sp. PRGB06 inhibited the mycelial growth of Botrytis cinerea, Colletotrichum coccodes, C. gleospoiroides, Rhizoctonia solani, and Sclerotia sclerotiorum under in vitro conditions. A significant increase, greater than that of the control, was also noted for growth parameters of the tomato test plants when the seeds were treated with PRGB06. Therefore, the results of the present study suggest that bacteria associated with insect larval guts possess PGP traits and positively influence plant growth. Therefore, insect gut bacteria as effective PGP agents represent an unexplored niche and may broaden the spectrum of beneficial bacteria available for crop production.
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ABSTRACT: The members of gram negative bacteria harbouring the silkworm are considered to be functionally important for improving silk yield and quality. The gut microbiology of lepidopteran insects received less attention in the earlier decades as it was thought that owing to their simple digestive tract, they do not harbour significant microbial load. However, recent studies using tools of biochemistry and molecular biology allow identification of new groups of microbes which have hitherto been unexplored. The present study focuses on the characterisation of gram negative microbes from the gut of silkworm using rapid identification kit, KB002 HiAssorted TM (Himedia Laboratories Pvt. Ltd., Mumbai). The gram negative bacteria identified and characterized from indigenous silkworm breeds using the rapid biochemical test kit were Escherichia coli, Yersinia enterocolitica and Klebsiella, Pneumaniae sp. pneumoniae. The details of isolation and characterization are discussed in this paper.
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ABSTRACT: The physiological and molecular responses of five strains of Streptomyces sp. (CAI-17, CAI-68, CAI-78, KAI-26 and KAI-27), with their proven potential for charcoal rot disease control in sorghum and plant growth-promotion (PGP) in sorghum and rice, were studied to understand the mechanisms causing the beneficial effects. In this investigation, those five strains were evaluated for their PGP capabilities in chickpea in the 2012-13 and 2013-14 post-rainy seasons. All of the Streptomyces sp. strains exhibited enhanced nodule number, nodule weight, root weight and shoot weight at 30 days after sowing (DAS) and pod number, pod weight, leaf area, leaf weight and stem weight at 60 DAS in both seasons over the un-inoculated control. At crop maturity, the Streptomyces strains had enhanced stover yield, grain yield, total dry matter and seed number plant(-1) in both seasons over the un-inoculated control. In the rhizosphere, the Streptomyces sp. also significantly enhanced microbial biomass carbon, dehydrogenase activity, total nitrogen, available phosphorous and organic carbon in both seasons over the un-inoculated control. Of the five strains of Streptomyces sp., CAI-17, CAI-68 and CAI-78 were superior to KAI-26 and KAI-27 in terms of their effects on root and shoot development, nodule formation and crop productivity. Scanning electron microscopy (SEM) micrographs had revealed the success in colonization of the chickpea roots by all five strains. Quantitative real-time PCR (qRT-PCR) analysis of selected PGP genes of actinomycetes revealed the selective up-regulation of indole-3-acetic acid (IAA)-related and siderophore-related genes by CAI-68 and of β-1,3-glucanase genes by KAI-26.SpringerPlus 12/2015; 4(1):31. DOI:10.1186/s40064-015-0811-3
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ABSTRACT: Various industrial, agricultural and military operations have released huge amounts of toxic heavy metals into the environment with deleterious effects on soils, water and air. Under metal stress, soil microorganisms including plant growth promoting bacteria (PGPB) have developed many strategies to evade the toxicity generated by the various heavy metals. Such metal resistant PGPB, when used as bioinoculant or biofertilizers, significantly improved the growth of plants in heavy metal contaminated/ stressed soils. Application of bacteria possessing metal detoxifying traits along with plant-beneficial properties is a cost effective and environmental friendly metal bioremediation approach. This review highlights the different mechanisms of metal resistance and plant growth promotion of metal resistant PGPB as well as the recent development in exploitation of these bacteria in bioremediation of heavy metals in different agroecosystems.Arabian Journal of Chemistry 11/2014; DOI:10.1016/j.arabjc.2014.11.020 · 2.68 Impact Factor