Shift in bacterial diversity in acidogenesis of gelatin and gluten seeded with various anaerobic digester inocula

Abstract

The aim of this study was to investigate divergence of bacteria degrading model proteins of food-processing wastewater. Gelatin and gluten were used as substrate to represent animal and plant proteins from food wastes, respectively. The inocula were obtained from eight full-scale anaerobic digestion reactors. Food-to-microorganism ratio was 3 g chemical oxygen demand equivalent of substrate per 1 g volatile suspended solids of inoculum. A first-order reaction model revealed reaction constants ranged 1.34 ≤ k ≤ 2.30 d−1 for gelatin and 0.63 ≤ k ≤ 1.69 d−1 for gluten. Metagenomic analysis of 16s rRNA sequences showed that dominant bacteria after gelatin degradation batch were different for each inocula. Klebsiella aerogenes, Hathewaya, Peptoclostridium, or Clostridium collagenovorans were most abundant. Klebsiella aerogenes was the most abundant species after gluten degradation for all inocula.