Endophytic bacteria colonizing the internal tissues of plants have attracted the attention of scientific communities in recent years for production of biodegradable polyesters like polyhydroxyalkanotaes (PHAs). A newly characterized bacterium, Bacillus cereus RCL 02 (GenBank accession no. KX458035), isolated from surface sterilized leaves of Ricinus communis L. has been explored for the production of poly(3-hydroxybutyrate) [P(3HB)], the most common PHA. As revealed by scanning electron microscopy, P(3HB) accumulating cells developed swellings or blebs and released the native granules as a function of autolysis. During growth in glucose containing mineral salts medium under batch fermentation, the isolate produced P(3HB) accounting 68% of its cell dry weight (CDW). Glucose and yeast extract when used in the ratio of 5:1, significantly influenced intracellular biopolyester accumulation (72.2%, CDW and 2.54 g/L). A further increase of polymer production (81%, CDW and 3.17 g/L) was accomplished in
Endophytic bacteria colonizing the internal tissues of plants are known to improve plant growth by a wide variety of mechanisms. This study envisages the isolation and evaluation of plant growth promoting attributes of bacterial endophytes in perennial fern
Ophioglossum reticulatum
L. A total of 20 phenotypically distinguishable bacterial endophytes were isolated from surface sterilized leaf lamina, petiole, rhizome and spike of
O. reticulatum
L. The Shannon-Weaver diversity index showed that the rhizome (1.54) harbor more diverse types of endophytic bacteria than in its petiole, leaf lamina and spike. The isolated endophytes were characterized on the basis of micromorphological and physio-biochemical characters and tentatively assigned to the genus
Bacillus
,
Pseudomonas
and
Staphylococcus
. The isolates showed distinct variations in their enzymatic activities, sugar fermentation and antibiotic sensitivity profile. A number of endophytic isolates showed plant growth promoting activities like production of indole-3-acetic acid (IAA) and siderophore, growth in nitrogen-free medium and solubilization of phosphate. Time course of growth and IAA production by the potent isolate
Bacillus
OPR 7 have been determined. Exploitation of such plant growth promoting endophytes appears to be one of the best options in increasing biomass yield and improving plant fitness and productivity.
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