Diet supplementation of Pediococcus pentosaceus in cobia (Rachycentron canadum) enhances growth rate, respiratory burst and resistance against photobacteriosis.

Cobia (Rachycentron canadum) is an economically important fish species for aquaculture in tropical and sub-tropical areas. Cobia aquaculture industry has severely damaged due to photobacteriosis caused by Photobacterium damselae subsp. piscicida (Pdp), especially in Taiwan. Antibiotics and vaccines have been applied to control Pdp infection, but the efficacy has been inconsistent. One species of lactic acid bacteria, Pediococcus pentosaceus strain 4012 (LAB 4012), was isolated from the intestine of adult cobia, and its culture supernatant can effectively inhibit Pdp growth in vitro. The acidic pH derived from metabolic acids in LAB culture supernatant was demonstrated to be an important factor for the suppression. After a 2-week feeding of LAB 4012, the growth rate of the fed cobia was 12% higher than that of the non-fed group, and the relative percentage of survival (RPS) of the fed cobia was found to be 74.4 in Pdp immersion challenge. In addition, the respiratory burst (RB) of peripheral blood leukocytes (PBL) in the LAB 4012-fed group was significantly higher than that of the non-fed group. Although feeding LAB 4012 did not improve specific antibody response in cobia after immunization with Pdp vaccine, it still significantly raised the survival rate by 22% over that of the non-fed group after Pdp immersion challenge. Judging by the quick induction of high protection against Pdp infection and promotion of growth in larvae, LAB 4012 was considered to be a viable probiotic for cobia aquaculture.

In vitro effects of Monascus purpureus on antioxidation activity during fermentation of Kinmen sorghum liquor waste.

Monascus purpureus CWT715 is a strain of red yeast rice that can scavenge free radicals when fermented with residual sorghum from Kinmen sorghum liquor waste (KSL). This study used KSL as the primary nutrient source in the production of metabolites from M. purpureus CWT715, whose antioxidant activity was tested on mouse embryonic liver cells (BNL CL.2). Image analysis of a comet assay was performed to evaluate DNA strand breaks, and thiobarbituric acid-reactive substance (TBARS) analysis was used to measure lipid peroxidation. The results demonstrate that, compared with the control, M. purpureus CWT715 pretreated with 100 µg/ml of fermentation broth reduced DNA damage by 61% and lipid peroxidation by 51%. Thus, KSL shows considerable potential as an antioxidant in functional foods. This is the first report on the use of Monascus species in the conversion of KSL to produce antioxidants.