Archaea Haloferax supplementation improves Artemia biomass production in hypersaline conditions

Abstract

Archaea, the third domain of life, are usually overlooked in aquaculture. Among them, the genus Haloferax is characterized by its tolerance for a wide salinity range and flexibility in using different organic substrates for cell growth. In order to clarify if Archaea can be predominant in bioflocs under certain conditions, Haloferax sp. was inoculated in an Artemia laboratory culture. Sucrose was added in the culture to stimulate Haloferax growth at C/N ratio of 10. Artemia were fed a formulated diet at four feeding rations (0, 10%, 50% and 100% of recommended feeding level). The experiment was carried out at salinity 100 g L−1 in 1-L culture cones, Haloferax was added at a density of 2 × 107 cells mL−1 before transferring Artemia into the culture system. The culture water was diluted brine with salinity of 100 g L−1. Artemia culture was supplemented with Haloferax at a final density of 107 cells mL−1 every week. The results show that supplementation of sucrose and Haloferax improved Artemia biomass production and significantly reduced TAN and nitrite content in the culture water (P < .05). High throughput sequencing analysis with bacterial and archaeal primer PCR amplification confirmed that Haloferax inoculation and sucrose addition changed both bacterial and archaeal structure and diversity, and resulted in Haloferax predominance in the bioflocs. Further study should focus on nutritional and health contribution of Haloferax to Artemia as well as on marine Archaea, to facilitate the research and application of Archaea in aquaculture.