Date Published: August 13, 2016
Publisher: Springer Berlin Heidelberg
Author(s): Stuti Sah, Rajni Singh.
Pseudomonas, an enormously diverse genus of the γ-Proteobacteria, is an important member of soil microbial communities. In this study, genetic heterogeneity and plant growth promotory property of Pseudomonas was compared within the group Pseudomonas sensu stricto isolated from the lesser explored niches of Himalayan region. A significant difference (P < 0.001 in total Pseudomonas count) was observed among the six types of soil samples collected from oak forest, fine forest, and agricultural soil. The highest numbers of bacteria were isolated from oak forest soil followed by pine forest soil and agricultural soil. 23.52 % of the total 238 isolates were siderophore producers and were identified as Pseudomonas on the basis of PCR amplification using 16S rDNA Pseudomonas specific primer. The molecular analysis by Jaccard’s similarity coefficient resulted into eight different clusters and six outlying branches. Some of the clusters include Pseudomonas from forest as well as agricultural land. Among the 51 isolates 100 % were siderophore and IAA producers, 68.62 % were phosphate solubilizers and 62.74 % HCN producers. The results reveal that isolates from lesser explored area possess beneficial properties and show genetic heterogeneity among them.
The genus Pseudomonas encompasses arguably one of the most complex, diverse, and ecologically significant group of bacteria on the planet. Members of the genus are found in large numbers in all the major natural environments (terrestrial, freshwater, and marine) and also form intimate associations with plants and animals. This universal distribution of Pseudomonas suggests a remarkable degree of physiological and genetic adaptability (Spiers et al. 2000). Thus, it is essential to understand the bacterial community structure and diversity in relation to environmental factors and ecosystem functions (Torsvik et al. 1996).
The diversity of plants and animals in forest and agroecosystem has been explored well, whereas the diversity of microorganism is often ignored. The greatest microbial diversity appears to reside in the soil (Zhou et al. 2003). Reduction in soil microbial diversity will result in the reduction of the functional capability of soil (Giller et al. 1997) as soil microorganisms play a very important role in soil fertility not only because of their ability to carry out biochemical transformation but also due to their importance as a source of mineral nutrients, cycling, and availability of nutrients required by the biological systems, the formation of soil organic matter, and decomposition of organic residues and detoxification of soil contaminants (Hendrix et al. 1990; Lavelle 1994) There have been studies on the distribution of microbial diversity in various environmental niches (Stolp 1988). Therefore, the diversity of microorganisms can be explored beneficially.