Abstract

Halobacteria belonging to Bacteria and Archaea domains has been identified as polyhydroxyalkanoates (PHA) producers. Halomonas sp. HG01, included in the class Gammaproteobacteria, was isolated from a saline in San Jose, Lambayeque, Peru. In this work, it was evaluate the potential of Halomonas sp. HG01 to produce PHA from different carbon sources. Halomonas sp. HG01 was cultured in shake-flasks (30 °C and 150 rpm) with mineral medium containing 100 g/L of NaCl and supplied with glucose, sucrose, fructose, lactose, xylose or glycerol as carbon source. When glucose and sucrose were used as the sole carbon source, similar values were observed in cell dry weight (4.77 g/L and 4.75 g/L, respectively), concentration (4.08 g/L and 3.98 g/L, respectively) and content (86% and 84%, respectively) of PHA, after 72 hour of culture. Moreover, when fructose was used as carbon source, the values obtained in cell dry weight, concentration and content of PHA decreased to 3.31 g/L, 2.27 g/L and 69%, respectively. The monomer detected was always 3-hydroxybutyrate (3HB). When the culture was supplied with lactose, xylose or glycerol, bacterial growth was negligible. Evolutive Engineering was performed in order to improve the glycerol uptake capability of Halomonas sp. HG01. Evolved clones reached values of cell dry weight, concentration and content of PHA of 3.16 g/L, 2 g/L and 63%, respectively. Therefore, cheap carbon sources can be used for the production of PHA by Halomonas sp. HG01 with high polymer content. The production of P3HB by Halomonas sp. HG01 using carbohydrates derived from sugarcane (sucrose, glucose and fructose) or byproduct from biodiesel production process (glycerol) could reduce production costs since the higher salt content avoid contamination allowing the use of simpler bioreactor designs.