Characterization of A45.2 Cultivated in Tannin Substrate for Use as a Potential Multifunctional Probiotic Yeast in Aquaculture.

At present, few yeast species have been evaluated for their beneficial capabilities as probiotics. A45.2, a carotenoid-producing yeast, was able to co-produce cell-associated tannase (CAT), gallic acid and viable cells with antioxidant activity when grown in a tannic acid substrate. The aim of this research study was to identify the potential uses of A45.2 obtained from a co-production system as a potential feed additive for aquaculture. A45.2 and its CAT displayed high tolerance in pH 2.0, pepsin, bile salts and pancreatin. Furthermore, its viable cells were characterized by moderate hydrophobicity, high auto-aggregation and moderate co-aggregation with , ser. Thyphimurium and . These attributes promoted A45.2 as a multifunctional probiotic yeast. In addition, the intact cells possessed antioxidant activities in a 100-150 μg gallic acid equivalent (GAE)/mL culture. Remarkably, the fermentation broth demonstrated higher antioxidant activity of 9.2 ± 1.8, 9.0 ± 0.9, and 9.8 ± 0.7 mg GAE/mL culture after FRAP, DPPH and ABTS assays, respectively. Furthermore, higher antimicrobial activity was observed against , and . Therefore, cultivation of A45.2 with a tannic acid substrate displayed significant potential as an effective multifunctional feed additive.