Artemia nauplii enriched with archaea Halorubrum increased survival and challenge tolerance of Litopenaeus vannamei postlarvae

Abstract

The red archaea contain carotenoids in their cell membrane, including lycopene, β-carotene and bacterioruberin, etc. Bacterioruberin is a novel bioactive compound, and is considered potential feed additives in food industry and aquaculture. In this study, the carotenoids containing archaea were applied in aquaculture for the first time. Halorubrum (Hrm) strain isolated from brine water was fermented in the culture medium. Hrm cells were fed to Litopenaeus vannamei postlarvae (PL) through Artemia enrichment. Considering the lack of fatty acids in Halorubrum, Artemia enriched with PUFA- riched microalgae Phaeodactylum tricornutum (Pht), and the mixture of Hrm and Pht (Hrm/Pht, 1/1) were included in the experiment. Starved Artemia was conducted as a control (Ctrl). The enrichment was performed at 28 °C for 12 h and at salinity 50 g L−1. The Artemia density was 200 nauplii mL−1 and the amount of enrichment agent was 0.3 g DW L−1. The results showed that the PLs in Hrm group had a better survival and growth when compared with other groups although no significant difference was observed (P>0.05). The PLs in Hrm and Hrm/Pht group had better salinity tolerance than the others. When exposed to the ammonia stress for 48 h, the PLs fed Hrm-enriched Artemia had significantly higher survival percentage than other groups (P<0.05). The content of malondialdehyde (MDA) in the hepatopancreas of ammonia stressed shrimps was significantly lower in enrichment group than the Ctrl group. Our study revealed that the supplementation of Halorubrum had positive effect on the osmotic stress and ammonia stress tolerance in L. vannamei, which is related to the dietary supplementation of Halorubrum, and might be linked to the antioxidative capacity of bacterioruberin existed in the archaeal cells. The present results suggested that red halophilic archaea Halorubrum could be high value feed additive in shrimp larviculture.