Acidic conditions 1 Acidic environment 1 Article 1 Bacteroidetes 1 Caldisericum 1 Chemical industry 1 Community composition 1 DNA polymerase 1 Desulfatirhabdium 1 Desulfotomaculum Fermenting bacteria 1 Firmicutes 1 Microbial diversity 1 Microorganisms 1 Operational taxonomic units 1 Process efficiency 1 Proteobacteria 1 RNA 16S 1 Sediment enrichments 1 Sphaerochaeta 1 Sulfur compounds 1 Synergistetes 1 Volatile fatty acids 1 acetate 1 acetic acid 1 acidic pH 1 acidification 1 acidophilic 1 adult 1 chemical analysis 1