Cultivation-dependent characterization of rhizobacterial communities from field grown Chinese cabbage Brassica campestris ssp pekinensis and screening of traits for potential plant growth promotion

Abstract

The composition of the bacterial community associated with plant roots is influenced by a variety of plant, environmental factors and also management practices. Our study aimed at detecting the root associated bacterial communities of Chinese cabbage under different fertilization regimes using cultivation dependent methods. The cultivable population was studied using plate count assay, fatty acid methyl ester (FAME) analysis and carbon substrate utilization (SU)using BIOLOG TM plates. Taxonomical identification of the isolates by FAME resulted in about 83% identification and they represented 9 and 14 different known bacterial genera from the rhizosphere and root interior respectively from Proteobacteria (a, b, and c), firmicutes (actinobacteria and the Bacillus groups) and Bacteroidetes. Pseudomonas and Bacillus were associated with the plants grown under all the fertilized conditions and actinobacteria could be observed only in rhizosphere of plants grown on unfertilized plots. FAME and BIOLOG profiles of the rhizosphere and endophytic isolates could separate them with reference to fertilization. Principal component analysis (PCA) on the BIOLOG SU revealed that the isolates were metabolically dissimilar. The diversity, as revealed by the diversity indices was greater among the isolates obtained from unfertilized samples than that of fertilized ones. The isolates analyzed for different traits related to plant growth promotion revealed differences between rhizosphere and endophytic isolates and also with reference to the treatments. The highest percentage of phosphate solubilizing bacteria (PSB) and 1-aminocyclopropane-1-carboxylic acid (ACC) utilizers was recorded in chemical fertilizer treated samples, followed by the organic fertilizer treated. The results from this study indicate that fertilizers have an effect on the root associated bacterial communities of Chinese cabbage and also on their physiological characteristics related to plant growth promotion.

Effect of transgenic alfalfa plants with introduced gene for Alfalfa Mosaic Virus coat protein on rhizosphere microbial community composition and physiological profile

“…Moreover, many authors report, that soil microbial communities are very plastic in composition and structure depending on different root zones, agricultural practices and environmental factors (Buckley & Schmidt 2003;Poonguzhali et al 2006). For example, Fang et al (2005) reported, that bacterial communities in maize rhizosphere were more affected by soil texture than by cultivation of transgenic cultivars.…”

“…Several studies showed the effect of the plant species, plant growth stage, soil type, field management practices as well as other environmental factors on the rhizosphere communities (Bachmann & Kinzel 1992;Di Cello et al 1997;Smalla et al 2001;Grayston et al 2001;Harichová et al 2006;Poonguzhali et al 2006). Possible impacts of transgenic plants on rhizosphere microbial communities are of concern because little is known about diversity-function relationships of microorganisms associated with transgenic plants in the soil environment (Bruinsma et al 2003).…”

Paenibacillus polysaccharolyticus sp. nov., a xylanolytic and cellulolytic bacteria isolated from leaves of Bamboo Phyllostachys aureosulcata

“…Most of the enzymic activities were assessed employing the API ZYM system (bio-M erieux). Utilization of polymeric substrates was qualitatively examined using Biolog GP2 MicroPlates as per previously published methodology [12,16,17]. The cellulose and xylose degradation potential of BL9…”

Identification of culturable endophytes in Champaka pineapple grown in an organic system

“…Bacteria related to A. brasilense, are able to colonize bananas (Weber et al, 1999;Mia et al, 2010) and especially graminous plants, leading to an increase of 16 to 30% in the production of wheat and corn grains (Hungria et al, 2010). A. caulinodans strains promote growth in rice seedlings (Senthilkumar et al, 2008), and Sphingobium yanoikuyae strains have activity of indol acetic acid production (Poonguzhaly et al, 2006). Other endophytes related to Enterobacter oryzae (Peng et al, 2009), Pantoea eucrina and Erwinia sp.…”