The extract from aerial part of Scutellaria baicalensis regulates gut microbiota in rabbit fish: Replacement of antibiotic fighting against pathogenic bacteria

The root of Scutellaria baicalensis is being used as herbal medicine, while its stem and leaf (aerial part) are considered as waste. The extract of aerial part of S. baicalensis, named as SBA here, has been shown to replace antibiotics in farming of Siganus fuscescens (rabbit fish), as to fight against marine pathogenic bacteria. To support the usage of SBA as feeding for aquaculture, the gut microbiota, after intake of the herbal extract, was determined. Here, the extract of SBA was mixed into the feeding of S. fuscescens that was cultured with a mixture of pathogenic bacteria. After 2 days of feeding, the gut content of fish was collected for the extraction and sequenced of 16S rDNA. The results indicated that the intake of SBA extract showed strong anti-bacterial effect, which inhibited the growth of pathogenic bacteria, i.e., Deltaproteobacteria and Fusobacteria. In contrast to antibiotic (enrofloxacin), the growth of probiotics, e.g., Erysipelotrichia, was promoted after intake of SBA. Our investigations showed the anti-bacterial effect of SBA extract in vivo, as well as its potential effect to promote the uptake of nutrients. The superiority of using this herbal extract in comparing to antibiotic was illustrated here, and which further suggested the possible development of recycling the waste product of S. baicalensis in fish aquaculture.