Gallagher, Daniella; Parker, David; Allen, Damian J.; Tsesmetzis, Nicolas
초록
<P><B>Abstract</B></P> <P>Significant low-cost biofuel production volumes could be achieved from commercial-scale silage by redirecting lactic acid fermentation to ethanol production. A temporal metagenomic analysis on ensiled sweet sorghum inoculated with an ethanologenic yeast has been conducted to understand the underlying microbial processes during bioethanol production. Individual silage buckets approximating silage piles were prepared with freshly harvested material and supplemented with ethanologenic yeast, sulfuric acid or both. The ensiling progress was assessed using high performance liquid chromatography, microbial taxonomic identification and abundance. The combined treatment with <I>Saccharomyces</I> and acid led to a steady reduction of bacterial abundance and microbial diversity with <I>Lactobacillus</I> becoming the dominant genus during the late timepoints. Furthermore, the addition of acid to inhibit bacterial growth hindered <I>Saccharomyces</I> ability to compete with native yeasts like <I>Candida</I>. Knowledge of the response of the in-situ microbial community to the various treatments during ensiling will help improve current methodologies for bioethanol production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ethanologenic yeast and acid addition reduced the microbial abundance and diversity. </LI> <LI> Acid addition delayed lactic acid production but had no impact on ethanol yield. </LI> <LI> <I>Lactobacillus</I> became the dominant genus during the late timepoints of ensiling. </LI> <LI> Native <I>Candida</I> species outcompeted the inoculated yeast on acid-treated silage. </LI> <LI> Majority of sugars were consumed by inoculated yeast within 12 h of ensiling. </LI> </UL> </P>