Effect of initial bacterial diversity on anaerobic degradation of long-chain fatty acids

Abstract

The effect of inocula from eight different digesters on the anaerobic degradation of palmitic acid (PA), stearic acid (SA), and oleic acid (OA) were evaluated in terms of degradation rate k, biodiversity, and key bacterial communities. The highest k were 0.213∙d−1, 0.110∙d−1, and 0.202∙d−1 for degradation of PA, SA, and OA, respectively. There was no significant correlation between the magnitude of k with bacterial diversity of the initial inoculum. 16S rRNA gene sequencing results at the end of each degradation process revealed that Syntrophomonas palmitatica, Smithella propionica, and Lentimicrobiaceae were the key bacteria in the methanogenic degradation of PA, Syntrophomonas sapovorans, S. propionica, and Lentimicrobiaceae were the key bacteria in the methanogenic degradation of SA, and Syntrophomonas zehnderi, Syntrophus aciditrophicus, and S. palmitatica were the key bacteria in the methanogenic degradation of OA. The information obtained from this study could be useful to guide selection of microbial sources for the start-up of continuous AD systems to treat wastes and wastewater that contain LCFAs.