Abstract

Polyhydroxyalkanoates (PHAs) are polyesters insoluble in water, with thermoplastic properties and 100 % biodegradable. They are synthesized by many different groups of bacteria and stored as intracellular granules. The PHA content and its composition are influenced by the producer strain, growth medium composition and conditions of incubation. It has been noted that isolation of new strains is essential to reduce the cost at industrial level. In this way, the present study deals with the biochemical profile of bacteria that are able to produce PHAs in minimal medium containing five different carbon sources, and which were isolated from soil samples of Atlantic Forest (Coruripe-AL). Three isolates (coded as LBPMA- BMA05, BMA10 and BMA13) able to degrade glucose, sucrose, glycerol, soybean oil and whey, were obtained and submitted to polymerase chain reaction (PCR), performed using specific primers for phaC-synthase (2.5 mM MgCl₂, 1 X buffer, 0.8 mM dNTPs, 10 μM each primer, 5 μg BSA, 3 % DMSO, 1 U Taq, H₂O to 25 μL). The isolated were also submitted to biochemical characterization using the analytical profile index API 20E (Biomerieux®). One isolate (BMA10) was chosen for growing in mineral salt medium supplemented with 2 % glucose during 72 h. Cell dry weight of the culture was gravimetrically determined and PHA extraction was carried out using solvent. The yield of PHA extracted was calculated as percentage of the cell dry weight obtained. Turbidity in minimal medium with the carbon sources was monitored for all the inoculated isolates, as an indicative parameter for the production of PHA. This potential was confirmed by amplicons of 492 pb of phaC-synthase detected by PCR. Results of biochemical profile of bacteria showed that no one produces H₂S and only BMA13 is able to degrade urea but did not show arginine dihydrolase activity. BMA10 was positive for utilization of all carbohydrates sources, except inositol, analyzed by API 20E. The preliminary identification with API 20E indicated that the isolates BMA05, BMA10 and BMA13 belong to the genera Pseudomonas, Klebsiella and Staphylococcus, respectively. Yield of PHA extracted from Klebsiella was low (1,26 %) under the conditions analyzed. For higher PHA accumulation, further experiments and monomer composition characterization are needed. These indigenous strains may be potential organisms for the production of biopolymer, once those genera have been studied as PHA-producing by different research groups.