Browsing by Author "Rashmi Tiwari"
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ItemDevelopment of corn silk as a biocarrier for Zymomonas mobilis biofilms in ethanol production from rice strawZ. mobilis cell immobilization has been proposed as an effective means of improving ethanol production. In this work, polystyrene and corn silk were used as biofilm developmental matrices for Z. mobilis ethanol production with rice straw hydrolysate as a substrate. Rice straw was hydrolyzed by dilute sulfuric acid (H2SO4) and enzymatic hydrolysis. The final hydrolysate contained furfural (271.95 ± 76.30 ppm), 5-hydroxymethyl furfural (0.07 ± 0.00 ppm), vanillin (1.81 ± 0.00 ppm), syringaldehyde (5.07 ± 0.83 ppm), 4- hydroxybenzaldehyde (4-HB) (2.39 ± 1.20 ppm) and acetic acid (0.26 ± 0.08%). Bacterial attachment or biofilm formation of Z. mobilis strain TISTR 551 on polystyrene and delignified corn silk carrier provided significant ethanol yields. Results showed up to 0.40 ± 0.15 g ethanol produced/g glucose consumed when Z. mobilis was immobilized on a polystyrene carrier and 0.51 ± 0.13 g ethanol produced/ g glucose consumed when immobilized on delignified corn silk carrier under batch fermentation by Z. mobilis TISTR 551 biofilm. The higher ethanol yield from immobilized, rather than free living, Z. mobilis could possibly be explained by a higher cell density, better control of anaerobic conditions and higher toxic tolerance of Z. mobilis biofilms over free cells.
ItemZymomonas mobilis biofilm formation on different types of carriersZymomonas mobilis biofilm have been proposed to enhance the bioethanol production from agricultural derived materials. Z. mobilis biofilm reactor has been prospected to be used for a large scale bioethanol production. The cost effective carrier for Z. mobilis biofilm reactor was searched. This study investigated the biofilm forming abilities of Z. mobilisstrain TISTR 551 and ZM4 on biotic (loofah and corn silk) or abiotic carriers (flatted sheet polyvinyl chloride, PVC). Biofilm formation was visualized for 3 consecutive days under the bright-field microscope. Only Z. mobilis TISTR551 represented the biofilm forming ability on corn silk under the microscopic observation, while no biofilm formation on loofah and PVC was observed. The mature biofilm was developed on day 3. The biofilm formation was also quantitatively analyzed based on the weight differentiation of the carrier and the carrier with the bacterial attachment. The net biomass weight of TISTR 551 and ZM4 on corn silk carrier was 0.6 ±0.1 g and 0.33± 0.1g respectively. Therefore, corn silk illustrates its potential to be used as a cost effective biocarrier for Z. mobilis biofilm.