Production of poly-beta-hydroxyalkanoates from soy molasses oligosaccharides by new, rapidly growing Bacillus species

Abstract

Aims: To isolate and characterize bacteria from nature capable of producing poly-beta-hydroxyalkanoates in high yields from soy molasses oligosaccharides.

Methods and results: Several strains of bacteria were obtained from enrichment cultures employing raffinose as major carbon source and inoculated with soybean field soil, lake sediment, or lake water. Many of the isolates were Bacillus species and produced polyhydroxyalkanoates (PHAs) to high yield. The raffinose-degrading isolates produced endospores, were highly saccharolytic, and both respired and fermented a variety of mono-, di-, tri- and tetrasaccharides. Strain CL1 produced 90% of cell dry mass as PHA from various sugars, including raffinose, and did so without requiring a nutrient limitation.

Conclusions: Strain CL1 could be the catalyst for an industrial fermentation converting soy molasses and other waste carbohydrates to PHAs. The properties of this organism that make it ideally suited for such a fermentation include (i) its ability to use a wide variety of plant-associated carbohydrates as PHA feedstocks; (ii) its rapid growth; (iii) its ability to grow under anoxic conditions; and (iv) its ability to produce spores.

Significance and impact of the study: This is the first report of bacteria capable of making biodegradable plastics to high yield from soy molasses oligosaccharides.