A comparative study between one-factor-at-a-time and minimum runs resolution-IV methods for enhancing the production of polysaccharide by Stenotrophomonas daejeonensis and Pseudomonas geniculate

Abstract Two bacterial strains were isolated from compost sample from Egypt and identified based on morphological and molecular characteristics using 16S rRNA sequence as Stenotrophomonas daejeonensis B14 and Pseudomonas geniculate Y8. Optimization of fermentation factors was performed by using one-factor-at-a-time (OFAT) and minimum runs resolution-IV statistical (Min Run Res IV) approaches. OFAT technique achieved the maximum polysaccharide dry weight at 30.1 and 25.3 g/L from S. daejeonensis B14 and P. geniculate Y8, respectively on medium containing 25% ( w / v ) blackstrap molasses (BSM) and 1.5 g/L corn steep liquor (CSL). The optimum pH was 6.5 and 7.5 for P. geniculate Y8 and S. daejeonensis B14, respectively. This medium inoculated with 5% ( v / v ) of standard inoculum of each strain individually, then incubated at 30 °C using shake flasks at 200 rpm for 96 h of the incubation period, respectively. Whereas, Min Run Res IV approach was recording that 3, among 8 factors had a significant effect on biopolymer production by both strains being fermentation time (72 h), BSM concentration (250 g/L), and shaking speed (at 250 rpm). This method resulted in a 7.3 and 9.2% increase in polysaccharide yield from S. daejeonensis B14 and P. geniculate Y8, respectively as compared to OFAT. The biopolymer was partially characterized according to physiochemical properties as follows; white colour crystalline, soluble in hot water, low viscosity and its contents of ash, total carbohydrate, total reducing sugar and total protein are ranged from 5.5 to 7.8%, 44.7 to 42.4%, 14.1 to 13.5%, 1.5 to 2.4%, respectively.