Gyra G. Gayapa, Irene Grace M. Lim, Lissa Angela Suyo (February 2009)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
Previous studies on effects of different culture conditions on gellan production focused on one carbon source.
This study compared gellan production using 3 carbon sources with 4 concentrations at 4 fermentation periods and 3 bacterial inoculum concentrations.
In phase 1. Sphingomonas paucimobilis was cultured in production media with 20,30 and 40 g/L glucose, sucrose and soluble starch for 48 hours. For sucrose and glucose, amount of gellan from various concentrations did not differ significantly For starch, 40 g/L. produced the most amount of gellan (One-way ANOVA, Fisher’s LSD, a 0.05).
In phase 2, different inoculum concentrations (-150-300 and 600 million CFU/mL) in 40 g/L. of the carbon sources were fermented for 8, 15, 24 and 48 hours. Three-way ANOVA (a = 0.05) showed that carbon source, inoculum concentration, and fermentation period have no simultaneous effects on amount of gellan and on conversion efficiency.
Main effect of carbon source (p=0.000, eta squared-0.554) on amount of gellan was stronger than that of inoculum concentration (p=0.008, eta squared 0.126). Separatec post-hoc analyses for each main effect showed highest amount of gellan for soluble starch and for 600 million CFU/ml.
Main effect analysis for carbon source (p=0.024) showed higher conversion efficiency for starch than glucose. Simple main effects analysis of the interaction between carbon source and fermentation period (p=0.013) showed that within carbon source, fermentation period influenced conversion efficiency in glucose, highest at 48-hrs. Within fermentation period, carbon source influenced conversion efficiency at 8 and 24 hrs fermentation, highest for soluble starch in both periods.
In general, carbon source is a prime consideration for gellan production followed by inoculum concentration. Within the conditions of the study, best gellan production may be attained for starch, for inoculum concentration of ~600 million CFU/ml, and for a fermentation period between 8 and 48 hours. Findings of this study may provide a better understanding of the interplay of the factors in gellan production.