Spatiotemporal dynamics of the microbial diversity on salt-preserved goatskins assessed by culturing and 16S rRNA gene amplicon sequencing

Abstract

Wet-salted skin, as a special artificial high-salt environment, is rich in protein, fat, collagen and other nutrient substrates, and is a rich resource of halotolerant and halophilic microorganisms. However, knowledge gaps regarding the microbial community structure and inter taxa associations of wet-salted skin are large. In this study, the spatiotemporal dynamics and community structure of microorganisms present on wet-salted goatskins were investigated using 16S rRNA gene amplicon sequencing and culturable technique. Alpha diversity analysis based on Sobs, Chao, Ace and Shannon indices revealed that microbial diversity on the wet-salted goatskins exhibited a trend of ‘down → up → down → flat’ with time. During preservation, genera belonging to the bacteria domain such as Acinetobacter, Weissella and Streptococcus were slowly dying out, whereas those belonging to halophilic archaea such as Natrialba and Haloterrigena were gradually flourishing. Moreover, to resist high-salt stress, microorganisms on the wet-salted goatskin gradually migrated from the outside to the inside, eventually leading to the microbial diversity inside the skin being the same as or even higher than that on the skin surface. Venn diagram analysis revealed that the strains of some genera, including Psychrobacter, Salimicrobium, Salinicola, Ornithinibacillus, Halomonas, Bacillus and Chromohalobacter, were distributed throughout the interior and exterior of the wet-salted goatskin and existed during various periods. Accordingly, 45 protease-producing halophilic or halotolerant microorganisms were isolated and screened from the wet-salted goatskin using the gradient dilution plate method. Importantly, 16S rRNA genes of some bacteria exhibited less than 99.5% similarity to valid published species, indicating that they likely are novel species and have a good potential for application.

Graphical Abstract