Screening and Isolation of Plant Growth Promoting, Halotolerant Endophytic Bacteria from Mangrove Plant Avicennia officinalis L. at Coastal Region of Corangi Andhra Pradesh

Abstract

Background: Main objective of this study is to isolate and characterize halo tolerant plant growth promoting endophytic bacteria from leaves and pneumatophores of mangrove plant Avicennia officinalis L. Isolates were also screened for their ability to provide resistance to extreme salt tolerance and temperatures and to produce exo enzymatic activity like catalase, amylase, protease, phosphate solubilization and plant growth promoting hormone (Indole 3-acetic acid). Methods: The present study was carried out during 2020-21 to 2021-22 at field and laboratory level. Eleven endophytic bacterial isolates were obtained from mangrove Avicennia officinalis L. grown at coastal region of Corangi Wildlife Sanctuary, East Godavari. All Isolates were enumerated, purified and preserved for further studies. Result: Out of eleven isolates obtained bacteria “AOL2” isolated from leaves of Avicennia officinalis L. was found promising in production of exo enzymes, Indole 3-acetic acid (IAA) and phosphate solubilization parameters. Isolate AOL2 was a Gram’s negative, motile, moderately halophilic, rod shaped diplobacilli which grows optimally at 32°C, pH 8.3 and had a salt tolerance of 10% NaCl. Microbial identification was carried out by morphological, biochemical and by 16S rRNA sequence. Based on nucleotide homology and phylogenetic analysis isolate AOL2 showed high degree of resemblance with Salinicola salarius. On the basis of the experimental findings, strain Salinicola salarius AOL2 had a capability in producing plant growth promoting substances, exo enzymes, phosphate solubilization ability and was first reported in endophytic bacteria isolated from Avicennia officinalis L. that can be studied further.