This research was supported by the Spanish Government (Spanish Ministry of Science and Innovation) through the TREASURE-MICROSALT (CTQ2017-83225-C2-2-R) and ECOPOLYVER-MACROPOLYVER (PID2020-112550RC22) projects.The biosynthesis of polyhydroxyalkanoates (PHAs) from industrial wastes by mixed
microbial cultures (MMCs) enriched in PHA-accumulating bacteria is a promising technology to
replace petroleum-based plastics. However, the populations’ dynamics in the PHA-accumulating
MMCs are not well known. Therefore, the main objective of this study was to address the shifts
in the size and structure of the bacterial communities in two lab-scale sequencing batch reactors
(SBRs) fed with fish-canning effluents and operated under non-saline (SBR-N, 0.5 g NaCl/L) or
saline (SBR-S, 10 g NaCl/L) conditions, by using a combination of quantitative PCR and Illumina
sequencing of bacterial 16S rRNA genes. A double growth limitation (DGL) strategy, in which
nitrogen availability was limited and uncoupled to carbon addition, strongly modulated the relative
abundances of the PHA-accumulating bacteria, leading to an increase in the accumulation of PHAs,
independently of the saline conditions (average 9.04 wt% and 11.69 wt%, maximum yields 22.03 wt%
and 26.33% SBR-N and SBR-S, respectively). On the other hand, no correlations were found among
the PHAs accumulation yields and the absolute abundances of total Bacteria, which decreased through
time in the SBR-N and did not present statistical differences in the SBR-S. Acinetobacter, Calothrix,
Dyella, Flavobacterium, Novosphingobium, Qipengyuania, and Tsukamurella were key PHA-accumulating
genera in both SBRs under the DGL strategy, which was revealed as a successful tool to obtain a
PHA-enriched MMC using fish-canning effluents.Spanish Government (Spanish Ministry of Science and Innovation) CTQ2017-83225-C2-2-R
PID2020-112550RC2
