1. Introduction
In order to minimize the increasing problem of non-degradable
plastic wastes, alternative sources of biodegradable plastics have
received much attention, especially polyhydroxyalkanoates
(PHAs). PHAs are biological origin-biodegradable polymers which
gained wider applications in commercial market. Poly-bhydroxybutyrate
(PHB), a most common type of PHA, is found
mainly as energy and carbon reserves inside unicellular cells that
face stress conditions (Balaji et al., 2013). There are several naturally
occurring microorganisms capable of PHB production under
modified nutrient conditions. The fermentative or chemoautotrophic
bacteria, such as Bacillus cereus SPV and Alcaligenes eutrophus
can produce 38% and 85% PHB of dry cell weight (dcw),
respectively (Valappil et al., 2007; Anderson and Dawes, 1990).