AUTHOR=Zhang Qian , Cai Yan , Chen Zihan , Shi Huizhong , Zhou Yongcan , Yang Yang , Tu Rui , Chen Guisen , Wang Shifeng 

TITLE=Screening and Characterization of Potential Antioxidant Probiotics Isolated from the Gut of Hybrid Grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂)

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.933304

DOI=10.3389/fmars.2022.933304

ISSN=2296-7745

ABSTRACT=Some symbiotic probiotics have antioxidant activities and could improve the antioxidant capacity of the host. However, there is no report on the screening of antioxidant probiotics in the gut of grouper. In this study, 369 out of 583 isolates obtained from the gut of hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) were non-hemolytic. Subsequent preliminary screening with DPPH scavenging rate assay resulted in 36 potential antioxidant isolates. After comprehensive evaluation with nine different antioxidant assays (DPPH scavenging rate, ABTS+ radical scavenging rate, iron ion reducing ability, reducing activity, O2-· scavenging rate,·OH scavenging rate, ferrous ion chelating rate, hydrogen peroxide (0.5 mM H2O2) tolerance, oxygen free radical scavenging ability (ORAC), et al.), 10 isolates with strong antioxidant abilities were screened from 36 potential antioxidant isolates. Then some other probiotic properties, such as simulated gastrointestinal fluid tolerance, adhesion, digestive enzyme activity and antibacterial activity of the 10 selected isolates were evaluated. All 10 isolates were also identified using molecular method. Finally, Vibrio rhodolitus GO 91 and Shewanella corallii GO 310, as representatives of the two genera resulting from identification of the 10 isolates, and with the best oval probiotic properties, were selected from the 10 isolates. GO 91 and GO 310 were further tested for their safety performances. Drug sensitivity test showed that GO91 and GO310 were sensitive to many commonly used aquaculture antibiotics. The In vivo challenge test of GO 91 and GO 310 didn’t cause any disease symptoms or death in hybrid grouper. Therefore, GO 91 and Go 310 show great potential to be used as probiotics in hybrid grouper farming.