POLIPHASIC SCREENING OF POLYHYDROXYALKANOATE-PRODUCING MICROORGANISMS

Abstract

Polyhydroxyalkanoates (PHAs) are fully biodegradable biopolyesters produced by many prokaryotes and accumulated as insoluble cytoplasmatic inclusions. The detection of these intracellular granule is usually provided using lipofilic azodyes, which are not specific. Another way to screen PHA-producing bacteria is through culture-independent molecular techniques such Polymerase Chain Reaction (PCR), and the search for new PHA-producer strains is essential to reduce the cost at industrial level. The application of these both methods is desirable. In the present study, 24 bacteria isolated from soil of the Atlantic forest in Maceio (AL, Brazil) and from agri-industrial sludge (Coruripe-AL, Brazil) were studied regarding to their capacity of growing in mineral salt medium, as indicative of PHA synthesis. All strains were submitted to biochemical characterization, whilst PCR has proved that isolates BMA-05, BMA-10, BMA-13 and BDL-07 has the gene phaC, which encodes a PHA synthase, the key for PHA synthesis. The amplification and sequencing of their 16S r-DNA region was able to identify these bacteria respectively as Pseudomonas fluorescens, Enterobacter aerogenes, Klebsiella oxytoca and Bacillus pumilus. The same minimal medium supplement with peptone demonstrated to induce growing of those strains.