Screening and identification of bacterial cellulose-producing strains from waste tobacco leaves and optimization of mixed-strains fermentation process
The bacterial cellulose-producing strains were isolated and screened from waste tobacco leaves,and the strains were identified by morpho-logic observation,physiological and biochemical tests and molecular biological identification.Using waste tobacco extract as carbon and nitrogen source,the mixed-strains fermentation was carried out with screened strain and Saccharomyces cerevisiae(1∶1),and the effects of waste tobacco extract addition,mixed-strains inoculum,pH,fermentation temperature and time on the yield of bacterial cellulose were investigated.The results showed that the fermentation process conditions were optimized by single factor,Plackett-Burman and Box-Behnken experiments.The results showed that a bac-terial cellulose-producing strain YC1 was selected and identified as Gluconobacter oxydans.The optimal mixed-strains fermentation process condi-tions were as follows:waste tobacco extract addition 10％,strain YC1 and S.cerevisiae(1∶1)inoculum 1.0％,initial pH 5.5,fermentation tempera-ture 30℃ and time 6 d.Under these optimal process conditions,the bacterial cellulose yield was the highest(2.71 g/L),which was 1.29 times higher than that of strain YC1 fermentation alone(1.18 g/L).
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