Cell wall deficient Saccharomyces cerevisiae strains as microbial diet for Artemia larvae: Protective effects against vibriosis and participation of phenoloxidase

Thousands of Artemia larvae (1000 to 4800 ind bottles− 1) were reared axenically with live and cooked cell wall deficient Saccharomyces cerevisiae (SC) strains as microbial diet to examine the protective effects against vibriosis and the participation of phenoloxidase. Firstly, six different cell wall deficient SC strains (fks1, knr4, kre6, chs3, gas1 and mnn9) were compared for best larval growth and phenoloxidase-like (PO-L) responses after infection with Vibrio proteolyticus. Live SC-mnn9 and SC-gas1 provided the best (P < 0.05) dietary support for Artemia growth and induced higher PO-L (P < 0.05). Secondly, SC-mnn9, SC-gas1 and the SC-wild type (WT) were prepared as cooked microbial diet and were offered to germfree (GF) larvae. Growth, PO-L responses and survival after infection with Vibrio campbelii were higher (P < 0.05) in larvae fed with cooked SC-mnn9 and SC-gas1 compared to SC-WT. Cooked SC-WT was a poor diet for GF Artemia, nevertheless, a rapid diet swap to cooked SC-gas1 or SC mnn9 improved the PO-L and survival against V. campbelii which suggested that the protective effect of SC-mnn9 and SC-gas1 could also be effective in larvae that have been undernourished. Artemia's PO-L seemed to vary in accordance to growth status, health or disease caused by vibriosis. This apparent capacity of Artemia to express PO-L under health and disease offers an interesting tool to explore its participation in the innate defense system of crustacean larval stages.