Metagenomic insights into the microbial community and biogas production pattern during anaerobic digestion of cow dung and mixed food waste

Abstract

BACKGROUND: The uncontrolled overproduction of fruit and vegetable waste causes serious environmental challenges such asemission of greenhouse gases. Anaerobic digestion (AD) is becoming a widely adopted technology for treatment of food wastewith the concomitant production of biogas. This study investigated the link between microbial community structure and biogasproduction when using cow dung and mixed fruit and vegetable waste (MFVW) as substrates.RESULTS: Semi-continuous stir tank reactors were used for AD of cow dung and MFVW over a period of 40 days. The highestaccumulative methane yield (112.9 L) was obtained from co- digestion, intermediate yield (59.5 L) was obtained from cow dungand lowest yield (6.1 L) from MFVW at the end of the digestion experiment. Polymerase chain reaction-denaturing gradientgel electrophoresis (PCR-DGGE) revealed higher bacterial and archaeal diversity indices in co-digestion in comparison tomono-digestion of cow dung and MFVW. High-throughput sequence analyses showed that operational taxonomic units (OTUs)belongingtothephylaBacteroidetes,followedbyFirmicutes,ActinobacteriaandProteobacteriaweredominantinalltreatments.CONCLUSION:Theresultsofthestudydemonstratedthattheenhancedmethaneproductioninco-digestioncouldbeattributedto the neutral pH and partial shift of archaea fromMethanosaetatoMethanosarcinarich communities