Plant growth-promoting potential of bacteria isolated from active volcano sites of Barren Island, India

To elucidate the biodiversity of plant growth-promoting (PGP) bacteria in active volcano sites of Barren Island, India, a total of 102 bacteria were isolated and screened for their multifunctional PGP properties. The results revealed that 21 isolates (20<bold>6</bold>%) survived heat shock at 72 degrees C and 11 (10<bold>8</bold>%) isolates were able to grow exposed to 25% NaCl (w/v). In assaying for PGP properties, 59 (57<bold>8</bold>%) isolates shown indole acetic acid (IAA) like substances production, 57 isolates (55<bold>9</bold>%) produced siderophore and 34 (33<bold>3</bold>%) solubilized inorganic phosphate qualitatively. Whereas in the production of extracellular enzymes, 42 isolates (41<bold>2</bold>%) produced protease and amylase, 26 (25<bold>5</bold>%) isolates produced lipase and 24 (23<bold>5</bold>%) isolates produced cellulase. In antagonistic activity, 30 isolates (29<bold>4</bold>%) were found antagonistic against Macrophomina sp., 20 isolates (19<bold>6</bold>%) against Rhizoctoniasolani and 15 isolates (14<bold>7</bold>%) against Sclerotium rolfsii. The results based on 16 rRNA gene sequencing revealed that the PGP bacteria belonged to 22 different species comprising 13 genera. Based on multifunctional properties, nine isolates were further selected to determine the PGP in brinjal and chilli seeds. Of the bacteria tested, the isolate BAN87 showed increased root and shoot length of both the crops followed in plant growth promotion by BAN86 and BAN43. The outcome of this research proves plausible practical applicability of these PGPB for crop production in soils of saline and arid environments.