Isolation and identification of intestinal cellulolytic bacteria from red swamp crayfish (Procambarus clarkii)

Abstract

Red swamp crayfish (Procambarus clarkii) like to eat aquatic plants. The intestinal microorganism plays an important role in cellulose degradation and utilization. Isolating bacteria which can degrade cellulose from the intestines of P. clarkii can provide a theoretical basis for the development of probiotics in forage for P. clarkii. Three selective media including carboxymethyl-cellulose, microcrystalline cellulose, and cellobiose were used in plate cultures for 48h and then dyed with Congo red. It was found that 5 strains produced hydrolytic rings on 3 culture media at 48h. Based on the results of 16S rRNA molecular analysis, strains C, E, G, H, and M were identified as Citrobacter sp., Staphylococcus sp., Acinetobacter johnsonii, Shewanella sp., and Aeromonas caviae, respectively. Specifically, Staphylococcus sp. exhibited the strongest capacity for the degradation of cellulose. Shewanella sp. showed the strongest degradation capacity for cellobiose. Acinetobacter johnsonii and Shewanella sp. can degrade cellulose and are expected to be used as probiotic feed for P. clarkii. This study can provide a theoretical basis for the healthy culture of P. clarkii.