Separation of polyhydroxyalkanoates-producing bacterial strains using PHA synthase gene and their evaluation for PHA deposition

Abstract

ABSTRACT In this study, a variety of samples were screened for the presence of PHA synthase gene. Results showed that 16 out of 102 isolated were positive for PHA respective genes. The highest prevalence was observed in Pseudomonas aeruginosa. The capability of PHA production was also shown by growing these strains on the defined medium and subsequent analysis using intracellular granules staining and Fourier transform infrared spectroscopy (FT-IR). The microscopic analysis showed that the positive strains accumulated PHA in the cell. The FT-IR analysis showed the presence of PHA peaks in the dried cells as well as in extraction product. P aeruginosa strain P7 showed higher concentration of PHA compared to the others as demonstrated by the highest respective peaks in FT-IR. Key words: Polyhydroxyalkanoates, Biodegradable polymers, PHA synthase gene, FTIR * Author for correspondence: basit_24@yahoo.com INTRODUCTION The accumulation of petrochemical polymers in the surroundings and growing awareness about the environmental pollution throughout the world has triggered the search for new products that are compatible with the environment. Currently, most polymer products are designed and prepared synthetically and very limited consideration is paid for their ultimate disposal. Of particular concern are throw-away plastic products, which are very suitable to use due to their physical properties. They have replaced wood, glass and other packaging materials since their emergence in 1940s (Ojumu 2004). However, these non-degradable plastics are building up in the environment at the rate of 25 million tons per year, which may persist for hundreds of years (Voaides 2010). It is worthy under these circumstances to design and develop biodegradable materials, which ensures an appropriate disposal with reference to the environment and eco system. In this regard, materials such as polyhydroxyalkanoates (PHAs), polylactic acid and others environment-friendly biopolymers are especially useful. Polyhydroxyalkanoates (PHA) are a class of naturally occurring polyesters that are produced and accumulated as inclusion bodies of carbon and energy reserve material in different microorganisms (Jendrossek 2009). It has been estimated that over 300 bacterial species and more than 90 genera, including Gram-negative and Gram-positive organisms accumulate various