A rapidly growing marine derived Bacillus sp. strain NQ-11/A2, identified as Bacillus megaterium, accumulated 61% polyhydroxyalkanoate by weight. Diverse carbon sources served as substrates for the accumulation of short chain length polyhydroxyalkanoate. Three to nine granules either single or attached as buds could be isolated intact from each cell. Maximum activity of polyhydroxyalkanoate synthase was associated with the granules. Granule-bound polyhydroxyalkanoate synthase had a K(m) of 7.1 x 10(-5) M for DL-beta-hydroxybutyryl-CoA. Temperature and pH optima for maximum activity were 30 degrees C and 7.0, respectively. Sodium ions were required for granule-bound polyhydroxyalkanoate synthase activity and inhibited by potassium. Granule-bound polyhydroxyalkanoate synthase was apparently covalently bound to the polyhydroxyalkanoate-core of the granules and affected by the chaotropic reagent urea. Detergents inhibited the granule-bound polyhydroxyalkanoate synthase drastically whilst glycerol and bovine serum albumin stabilized the synthase.
This study reports the mechanisms of phosphate solubilization present in alkaliphilic Bacillus marisflavi FA7. The strain obtained from sediment samples of mangrove ecosystem exhibited different mechanisms to solubilize inorganic phosphate and mineralize organic phosphate under alkaline conditions. It reduced the pH of the medium that showed near perfect correlation with tri-calcium phosphate solubilization. Organic acids produced by the strain were detected in broth. Maximum decrease in pH of the medium was observed with NH 4 Cl as an inorganic nitrogen source. This indicated involvement of proton extrusion mechanism toward phosphate solubilization during ammonium uptake. It produced exopolysaccharide, but failed to produce siderophore. Bacillus marisflavi FA7 produced extracellular alkaline phosphatase having molecular weight of 175-200 kDa. The pH optimum for maximum enzyme activity was 10.1 and K m of 1.13 M p-nitrophenolphosphate. This is the first study to report the highest tri-calcium phosphate solubilization by an alkaliphilic bacterium.
Magnetite crystals and freshwaters), to deep sea sediments, salt marshes, wet soils, hot springs and even in extremely cold regions [22][23][24][25][26]. Their diversity in terms of morphology, physiology and phylogeny is outstanding. The morphological types include cocci, bacilli, vibrios, spirilla, ovoid, giant J o u rn al of M ic ro b ia l & Bioc h e m ic a l Te chno lo g y
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