Resumo

INTRODUCTION: Polyhydroxyalkanoates (PHAs) are natural polymers with thermoplastic properties and a wide range of potential applications. They are biosynthesized and biodegraded and can be produced from renewable carbon sources. In the present work, samples of Atlantic Forest (AF) soil and sludge (from an agroindustry-Effluent Treatment Station, in Coruripe-AL, Brazil) were obtained for screening of PHAs accumulating bacteria. MATERIALS AND METHODS: Such samples were inoculated on a stimulating liquid medium for this polymer production during 72h. Then, aliquots of the serial dilution were inoculated on Nutrient Agar+fluconazole, allowing the isolation of bacteria (23 strains) which were submitted to morphological and biochemical characterization in differential/selecting media to fermentation of suggars; degradation of Tween 80, nucleic acids, starch, proteins; spore formation and NaCl tolerance; PHA production with glucose and sucrose as unique sources of carbon (evidenced through Sudan Black coloration). RESULTS AND DISCUSSION: Most of obtained bacteria showed oxidative and fermentative metabolism for glucose, being lipolitic, non-motile and incapable of producing indol or H2S. Except the isolate BMA10, all of them were able to secrete gelatinase and caseinase, being two (BMA07 and BLD05) Actinobacteria unable to PHA production. All the six strains unable to tolerate high salt concentration, as well as the three able to degrade DNA, were isolated from AF soil. Bacteria isolated from the sludge were more biochemically homogeneous. Strain BMA05 is a strong candidate to be used on biotechnological applications, once it is able not only to degrade starch, casein and gelatin, but also to produce PHA under nitrogen limiting condition with the two sugars investigated.