HRTand nutrients a¡ect bacterial communities grown on recirculationaquaculture systeme¥uents
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Date
2007-04
Journal Title
Journal ISSN
Volume Title
Publisher
John Wiley & Sons Ltd.
Abstract
In a recirculation aquaculture system the drumfilter effluent can be used as
substrate for heterotrophic bacterial production, which can be recycled as feed.
Because the bacteria might contain pathogens, which could reduce its suitability as
feed, it is important to characterize these communities. Bacteria were produced in
growth reactors under different conditions: 7 h hydraulic retention time (HRT) vs.
2 h, sodium acetate vs. molasses, and ammonia vs. nitrate. The community of the
drumfilter effluent was different from those found in the reactors. However, all
major community components were present in the effluent and reactor broths.
HRT influenced the bacteria community, resulting in a DGGE profile dominated
by a band corresponding to an Acinetobacter sp.-related population at 2 h HRT
compared to 7 h HRT, where bands indicative of a-proteobacterial populations
most closely related to Rhizobium and Shinella spp. were most abundant. Molasses
influenced the bacterial community. It was dominated by an Aquaspirillum
serpens-related population. Providing total ammonia nitrogen (TAN) in addition
to nitrate led to the occurrence of bacteria close to Sphaerotilus spp., Flavobacterium
mizutaii and Jonesia spp. It was concluded from these results that a 6–7 h HRT
is recommended, and that the type of substrate is less important, and results in
communities with a comparably low pathogenic risk.
Description
Keywords
bacteria, community, aquaculture, waste conversion, 16S rRNA gene