Mass production of nitrifying bacterial consortia for the rapid establishment of nitrification in saline recirculating aquaculture systems

Abstract

Two distinct nitrifying bacterial consortia, namely an ammonia oxidizing non-penaeid culture (AMO NPCU-1) and an ammonia oxidizing penaeid culture (AMOPCU-1), have been mass produced in a nitrifying bacterial consortia production unit (NBCPU). The consortia, maintained at 4°C were activated and cultured in a 2 l fermentor initially. At this stage the net biomass (0.105 and 0.112 g/l), maximum specific growth rate (0.112 and 0.105/h) and yield coefficients (1.315 and 2.08) were calculated respectively, for AMONPCU-1 and AMOPCU-1 on attaining stationary growth phase. Subsequently on mass production in a 200 l NBCPU under optimized culture conditions, the total amounts of NH 4 ? -N removed by AMONPCU-1 and AMOPCU-1 were 1.948 and 1.242 g/l within 160 and 270 days, respectively. Total alkalinity reduction of 11.7-14.4 and 7.5-9.1 g/l were observed which led to the consumption of 78 and 62 g Na 2 CO 3 . The yield coefficient and biomass of AMONPCU-1 were 0.67 and 125.3 g/l and those of AMOPCU-1 were 1.23 and 165 g/l. The higher yield coefficient and growth rate of AMOPCU-1 suggest better energy conversion efficiency and higher CO 2 fixation potential. Both of the consortia were dominated by Nitrosomonas-like organisms. The consortia may find application in the establishment of nitrification within marine and brackish water culture systems.

Impact of Organic Carbons Addition on the Enrichment Culture of Nitrifying Biofloc from Aquaculture Water: Process, Efficiency, and Microbial Community

“…Moreover, three kinds of low molecular and commonly used organic carbon sources, including sodium acetate, sodium citrate, and sucrose, were added into the enrichment medium for the enhancement of the enrichment process [27,38]. Good results were achieved in the enrichment period and biomass production compared to previous similar studies [16,24,25,37]. The enrichment process of nitrifying bioflocs was clearly shown by the concentration changes of NH 4 + -N, NO 2 − -N, NO 3 − -N, TIN, and input TN in the reactors with different organic carbon additions (Figure 1).…”

“…They jointly execute a two-step process of nitrification, in which ammonia is first oxidized to nitrite by AOB and subsequently to nitrate by NOB. Due to slow growth and attachment characteristics, long periods are often required to obtain nitrifying bacterial consortia, especially for the enrichment from natural environment using autotrophic inorganic mediums [24][25][26]. Bioflocs are typically microbial aggregates, and their formation and development are accompanied by the attachment growth process of nitrifying bacteria [7,12,13].…”

A review of influencing factors on a recirculating aquaculture system: Environmental conditions, feeding strategies, and disinfection methods

“…In RAS, the pH of water will be reduced because of CO 2 emission by biological respiration and acid generated by nitrification. Generally, to maintain the stable operation of RAS and ensure the normal growth of aquaculture organisms, weak alkaline reagents such as sodium bicarbonate and sodium carbonate will be added to adjust the pH to within an appropriate range (Kumar et al, 2009; Loyless & Malone, 1997; Masser et al, 1999).…”

Ammonia induced toxico‐physiological responses in fish and management interventions

“…Immobilizing nitrifying bacterial consortia on wood particles has improved nitrification in zero water exchange shrimp culture ponds 195 . Different biofilters/bioreactors were successfully demonstrated in recirculating aquaculture systems (RAS) to control the ammonia concentration, mainly relying on chemolithoautotrophic nitrifying bacteria 196–200 . The aquaponic system, a combination of hydroponic and RAS, mainly relies on autotrophic nitrifiers for ammonia control along with the plants 201,202 .…”