Identification of a poly(3-hydroxybutyrate)-degrading bacterium isolated from coastal seawater in Japan as Shewanella sp.

A poly[(R)-3-hydroxybutyrate] [P(3HB)]-degrading bacterium (strain JKCM-AJ-6,1 alpha) was isolated from coastal seawater near the port of Yaizu, Suruga Bay, Japan. The strain grew well in a marine mineral medium supplemented with P(3HB) powder as the sole carbon source. Phylogenetic analysis revealed that the strain JKCM-AJ-6,1 alpha, belonged to the genus Shewanella. The isolate was unable to grow at temperatures above 50 degrees C, and the optimum range of growth temperatures was 30 degrees C-37 degrees C; however, the optimum temperature for degradation of P(3HB) was 15 degrees C. The maximum specific growth rate (mu = 1.0 h(-1)) was attained at a NaCl concentration of 0.2 M, but the strain was able to grow even in the presence of 0.8 M NaCl. This suggests that the strain is a typical marine bacterium. This is the first report showing P(3HB) depolymerase activity in a member of the genus Shewanella. It is concluded that the genus Shewanella may be one of the key bacterial groups involved in the P(3HB) cycle in marine environments. (C) 2016 Elsevier Ltd. All rights reserved.