Statistical optimization of culture conditions to improve cell density of Komagataeibacter medellinensis NBRC 3288: the first step towards to optimize bacterial cellulose production

Abstract

The cell density yield of Komagataeibacter medellinensis NBRC 3288 was optimized applying response surface methodology (RSM) for the first time with this strain. Four factors were evaluated: glucose, initial pH, MgSO4 and KH2PO4, these were analyzed in a fractional factorial design to verify which were important to cell density yield. The best treatment assayed showed a yield of 1.09 OD600 and analysis of variance (ANOVA) selected glucose, inital pH and KH2PO4 as the significant factors. Next, a new experimental region with center point at glucose 0.5 %(wt./v), initial pH at 5.58 and KH2PO4 0.058 %(wt./v) was obtained by steepest ascent method and used to optimize biomass yield by Box-Behnken design. The results indicate that the optimum culture medium conditions predicted by the mathematical model (R2adj=72.09 %) were: glucose, 0.54 %(wt./v); peptone, 0.5 %(wt./v); yeast extract, 0.5 %(wt./v); KH2PO4, 0.059 %(wt./v); MgSO4, 0.025 %(wt./v); NaH2PO4, 0.267 %(wt./v) and pH, 5.18 (adjusted with citric acid, 0.2 %(wt./v)) to obtain an optimum cell density yield of 2.85 OD600 with an improve of 68 % respect to the best result obtained at the begin, as well as m improved 34.78 % and a reduction in cost of culture medium due to glucose concentration reduction of 75 %.\n\nImportanceDespite the important role of producer-strain play in bacterial cellulose production, until now there is not anu report about how to improve cell density, as a primary stage, that allows reach higher production of BC in later stages. In this study, was optimized the growth conditions of K. medellinensis (a BC producer in acid pH) in order to increase the cell density, as the primer stage in the whole process to optimize the production of BC, which is a very important supplie in different fields of science such as: food, materials, water treatment, tissue engineering, etc. The optimization process was achieved with savings in production costs of the culture medium, through the reduction of glucose concentration by 75 % and through the reduction of the microorganisms growth time.