Economical production of poly(γ-glutamic acid) using untreated cane molasses and monosodium glutamate waste liquor by Bacillus subtilis NX-2

摘要

The production of poly(γ-glutamic acid) by Bacillus subtilis NX-2 from cane molasses and monosodium glutamate waste liquor (MGWL) was studied for the first time in this work. When batch fermentation was carried out with untreated molasses, 33.6±0.37gL -1 PGA was obtained with a productivity of 0.46±0.006gL ~(-1)h ~(-1). In order to minimize the substrate inhibition, fed-batch fermentation was performed with untreated or hydrolyzed molasses in 7.5L bioreactor, giving 50.2±0.53 and 51.1±0.51gL ~(-1) of PGA at 96h, respectively. Further studies were carried out by using MGWL as another carbon source, resulting in a PGA concentration of 52.1±0.52gL ~(-1) with a productivity of 0.54±0.003gL ~(-1)h ~(-1). These results suggest that the low-cost cane molasses and MGWL can be used for the environmental-friendly and economical production of PGA by B. subtilis NX-2.