CONICET | Buscador de Institutos y Recursos Humanos

Anaerobic digestionconstitutes a sustainable process widely used for organic waste management thathas the advantage of generating biogas in addition to the stabilization oforganic matter. The process of anaerobic digestion depends on the assembly of acomplex microbial community, in which methanogenic archaea and syntrophicbacteria are the leading actors. It has been observed that for certainsubstrates, a suitable inoculum source may be critical for efficient biogasproduction. However, the availability of adequate inocula is severely limitedat the local level, due to the very low degree of adoption of technologiesbased on anaerobic digestion. This work aims at understanding the adaptation ofinocula arising from different sources to food waste. Four lab- scaleanaerobic reactors (5 L) were operated during 91 days and fed daily withincreasing concentrations of food waste. Reactor operational parameters,including biogas production, volatile solids (VS), alkalinity and volatilefatty acids concentration (VFA) were measured on regular basis. Metagenomic DNAwas obtained from sludge samples taken weekly. Methanogenic archaea abundancewas estimated using qPCR assays, whereas total microbial community analysis wasconducted using amplicon sequencing with primers for the V3-V4 rRNA16S region. Specific biogasproduction (Biogas/VS) and volatile fatty acids (VFA) varied depending on theinoculum´s source and feeding rate. Using USEARCH, OTUs were defined at 97%,obtaining 2690 OTUs that then were classified with rdp database. Under ourexperimental set up, adaptation to food waste was associated to the presence ofacetoclastic methanogenic archaea from Methanosaeta genus, which weremapped with high abundance when biogas production was higher and identified askey taxa associated to process stability. This results underlies the criticalrole of the inoculum source for reactor start up. We are currently analyzingmethanogenic archaea applying amplicon sequencing of the mcrA gene,which encodes methyl coenzyme-M reductase.