First Steps in the Development of a Wheat Flour Based Lactic Acid Fermentation Technology. Culture Medium Optimization

Batch fermentation experiments were performed to evaluate the potentials of different fractions of wheat as alternative carbon and nitrogen source for an economical production of lactic acid by a homofermentative mesophilic bacterium (Lactobacillus sp. MKT-878 NCAIM B02375). Hydrolysing the starch content of wheat results in well consumable glucose solution, and simultaneously by hydrolysing the insoluble protein content (gluten) of wheat the nitrogen source can be assured as well. The necessary yeast extract concentration was 30 g L–1 on hydrolysed wheat starch solution without gluten fraction. By means of an optimization process we found that the gluten fraction can substitute the major part of the added yeast extract as nitrogen source, and on the basis of a statistical experimental design we created an optimized medium with 8 g L–1 yeast extract and 16 g L–1 gluten supplementation, resulting in 3.54 g L–1h–1 productivity which can be considered as an industrially acceptable process output

Evaluation of three methanol feed strategies for recombinant Pichia pastoris Muts fermentation

Methylotrophic yeast Pichia pastoris is an ideal host organism for recombinant protein production. However, adequate methanol feed is still a critical point of successful product formation in P. pastoris Mut S fermentations. Three methanol feed strategies were tested: an organic vapor sensor, a dissolved oxygen controlled methanol addition and a pre-determined model, as well. The organic vapor sensor proved to be unsuitable for methanol concentration measurements when samples were taken from the head space of the bioreactor, but may have the potential to substitute expensive gas analyzers in methanol fed-batch with a suitable selector submerged into the fermentation media. Dissolved oxygen and substrate consumption did not show strict mathematical relation. However, drop of dissolved oxygen tension for periodic methanol addition may be applied for the determination of the substrate concentration in the media. The rate of methanol consumption shows peaks at 0.45 and 0.95% (v/v) substrate concentrations. The rate of the specific methanol consumption of our model organism was determined. Based on the value of 0.023 h Ś1, which is significantly less than suggested by earlier experiments, a successful pre-determined methanol feed strategy was set up