Polyhydroxyalkanoates production by actinobacteria isolated from soil

Polyhydroxyalkanoates (PHAs) are biodegradable and renewable polymers produced by a wide range of bacterial groups. New microbial bioprospection approaches have become an important way to find new PHA producers and new synthesized polymers. Over the past years, bacteria belonging to actinomycetes group have become known as PHA producers, such as Nocardia and Rhodococcus species, Kineosphaera limosa Liu et a]. 2002, and, more recently, Streptomyces species. In this paper, we disclose that there are more actinobacteria PHA producers in addition to the genera cited. Some unusual genera, such as Streptoalloteichus, and some genera frequently present in soil, such as Streptacidiphilus, have been found. Thirty-four isolates were able to accumulate poly(3-hydroxybutyrate) and a number of these have traces of poly(3-hydroxyvalerate) when cultivated on glucose or glucose and casein as carbon source. Furthermore, some strains showed traces of medium chain length PHA. Transmission electron microscopy demonstrated that the PHA accumulation occurs in hyphae and spores.

New alk genes detected in Antarctic marine sediments

Alkane monooxygenases (Alk) are the key enzymes for alkane degradation. In order to understand the dispersion and diversity of alk genes in Antarctic marine environments, this study analysed by clone libraries the presence and diversity of alk genes (alkB and alkM) in sediments from Admiralty Bay, King George Island, Peninsula Antarctica. The results show a differential distribution of alk genes between the sites, and the predominant presence of new alk genes, mainly in the pristine site. Sequences presented 53.10-69.60% nucleotide identity and 50.90-73.40% amino acid identity to alkB genes described in Silicibacter pomeroyi, Gordonia sp., Prauserella rugosa, Nocardioides sp., Rhodococcus sp., Nocardia farcinica, Pseudomonas putida, Acidisphaera sp., Alcanivorax borkumensis, and alkM described in Acinetobacter sp. This is the first time that the gene alkM was detected and described in Antarctic marine environments. The presence of a range of previously undescribed alk genes indicates the need for further studies in this environment.