Pseudonocardia filamentous bulking sludge in an industrial wastewater treatment plant as revealed by Illumina amplicon sequencing

Abstract

In this study, 16S rRNA gene amplicon sequencing was performed to identify bulking filamentous bacteria in an industrial wastewater treatment plant that threats effluents of bioethanol production process from cereal cooking. The presence of Pseudonocardia sp. was confirmed by comparing the 16SrRNA of the most abundantly amplified sequence (OTU; 12.35%) with corresponding nucleotides present in two genomic databases. The Pseudonocardia species identified was closely related to Pseudonocardia spinosa. Over 50 different types of filamentous microorganisms have been found to cause problems with bulking and foaming, but Pseudonocardia has, until now, not been described to be among them. In addition, the 16S rRNA dataset was analyzed to reveal bacterial community composition during sludge bulking. Candidatus Competibacter was identified as the second most abundant sequence (OTU, 10.04%). Comparative data from samples obtained before and after appearance of Pseudonocardia suggest that a decrease in nutrients could be one of the main factors affecting sludge bulking generated by this species. The outcomes of this study are expected to provide an important insight into the role of Pseudonocardia in bulking in industrial wastewater treatment plants.