Phylogenetical coherence of Pseudomonas in unexplored soils of Himalayan region

Abstract

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.

Pseudomonas mediated nutritional and growth promotional activities for sustainable food security

“…Phytohormone synthesis is linked with production of auxin similar to indole-3-acetic acid (IAA) which act as signaling molecules for regulating plant developmental growth, organogenesis stimulation, cell growth, division, and differentiation. Pseudomonas fluorescens, Pseudomonas putida, and Pseudomonas syringae are the most distinguished and active strains which synthesize auxin and utilize L -Trp (precursor molecule) toward PGPR activities (( Costacurta and Vanderleyden, 1995 ); Sah and Singh, 2016 ). A high concentration of L -Trp-corresponds to high IAA production, which inhibits the effective parameters required for plant growth (Costacurta and Vanderleyden, 1995; Mia and Shamsuddin, 2010 ).…”

“…Approximately 1 billion species of bacteria exist on Earth. Out of them, 5000 species identified yet ( Sah and Singh, 2016 ). Moreover, surface soil microbes present on the Earth consider around 10 billion microbes per gram.…”

“…One gram of that soil contains approximately 4000 distinct bacterial genomes. These units estimate an enormous mass diversity significance while showing the progressive competition in the rhizospheric complement ( Sah and Singh, 2016 ). The total percentage value of the microbes present in the soil constituents is <0.4–0.5% w/w.…”

“…The widespread occurrence of Pseudomonas indicates its adaptability through molecular, environmental, and physiological diversity ( Sah and Singh, 2016 ). The classification of Pseudomonas covered as a part of Bergy's Manual (in 1923), based on its phenotypic characteristics, described various media presenting comparable plate counts select different bacterial types reaching several diversity estimates within the same soil.…”

“…Pseudomonas has simple nutritional requirements due to their properties in the degradation of distinct substrates, aromatic chemicals, halogenated derivatives, and recalcitrant organic residues. ( Sah and Singh, 2016 ) studied the growth of various Pseudomonas strains on several different organic substrates, reporting great diversity in genus Pseudomonas . Taxonomic characterization of the Pseudomonas with the advancement in the DNA fingerprinting techniques like RFLP, 16S rDNA, and ARDRA of different groups with monophyla and several before included Pseudomonas species moved to distinct another genus yet, Pseudomonas sensu-stricto persists influential diversity, for example, P. plecoglossicida, P. simiae, P. salomonii, P. palleroniana and P. costantinii ( Verma et al., 2019 a).…”