Butyric Acid Fermentation from Rice Straw with Undefined Mixed Culture: Enhancement by pH Control

Abstract

This study aimed to find out the optimum pH range and a buffer feeding method for butyric acid production from rice straw by undefined mixed culture. A serial experiment was conducted at various pH levels from 5.0 to 7.0. The results showed that neutral pH improved rice straw conversion and hence carboxylic acid production. The highest butyric acid production was achieved at pH range of 6.0 to 6.5. Another serial experiment was performed at pH 6.0 to 6.5 buffered with CaCO3, NaHCO3, NH4HCO3 and their combinations, respectively. The results indicated that different buffers had different effects on product spectrum, and that CaCO3 combined with NaHCO3 was an effective buffer for butyric acid production. This study presents an alternative way for butyric acid production from lignocellulosic biomass without supplementary cellulolytic enzyme.

Consolidated Bioprocessing for Butyric Acid Production from Rice Straw with Undefined Mixed Culture

“…A mixed culture produces mixed products. It has been revealed that the cellulose-degrading butyrate-producing mixed culture used in this study is composed of cellulolytic and xylanolytic bacteria, butyrate-producing bacteria and other acidogenic bacteria, including Bacteroides cellulosilyticus, Clostridium cellulolyticum, Bacteroides graminisolvens, Bacteroides xylanisolvens, Cellulosilyticum ruminicola, Eubacterium xylanophilum, Clostridium polysaccharolyticum, Clostridium saccharolyticum, Thermincola carboxydiphila, Clostridium xylanolyticum, Clostridium algidixylanolyticum, Xylanibacter oryzae (Ai et al, 2013 ). n -Butyric and acetic acids were the main liquid products, and another six carboxylic acids, including propionic, i -butyric, i -valeric, n -valeric, i -caproic and n -caproic, were detected in the fermentation broth.…”

“…The cellulolytic butyrate-producing mixed culture was derived from cattle manure, pig manure compost, corn field soil and rotten wood (Ai et al, 2013 ). The cattle manure, pig manure compost and corn field soil were collected from the suburb of Harbin, China.…”

“…Inspired by the carboxylate platform and CBP, undefined mixed culture-based fermentation technology is a promising alternative strategy for butyric acid production from lignocellulosic biomass. In a previous study, an anaerobic microbial community with stable cellulose-degrading potential and high selectivity for butyric acid production was selected from a combination of cattle manure, pig manure compost, corn field soil and rotten wood (Ai et al, 2013 ). To further demonstrate the feasibility and potential of undefined mixed culture for butyric acid production, a CBP process was investigated to produce butyric acid from NaOH pretreated rice straw using a cellulose-degrading butyric acid-producing microbial community, and its fermentation performance in batch and semi-continuous operations was evaluated.…”

Enhanced methane production through bioaugmentation of butyrate‐oxidizing hydrogen‐producing acetogens in anaerobic wastewater treatment

“…Consequently, it is possible to assert that the relatively high methane production may also be achieved by the inoculation and bioaugmentation of butyrate-oxidizing HPAs [21]. Furthermore, butyric acid can be fermented during anaerobic wastewater treatment [4,22,23], and the terminal products become extensively diverse [24][25][26]. Degradation of butyric acid by HPAs occurs considerably more easily than that of propionic acid; thus, in this work, a microflora dominated by HPAs that oxidize butyric acid was obtained by subculture of anaerobic sludge, and the efficiency of this microflora in enhancing methane production and anaerobic organic wastewater treatment was evaluated.…”

Current advances in organic acid production from organic wastes by using microbial co‐cultivation systems

“…Meanwhile, CBP for butyric acid production from lignocellulose could also be achieved by using undefined microbial consortia: 6.01 g.L ‐1 of butyric acid was produced using the microbial community, which combined inoculums from cattle manure, pig manure compost, soil from corn fields, and rotten wood. To increase butyric acid production, the optimum pH range and appropriate buffer agents for butyric acid production from rice straw were identified .…”