Inhibitory effects of chitosan combined with nisin on Shewanella spp. isolated from Pseudosciaena crocea

- S. algae and S. putrefaciens are involved in spoilage of P. crocea.
- S. putrefaciens and S. algae can be monitored by PLFA analysis.
- Combined with nisin, chitosan presented inhibitory effects on them.

Application of natural preservative agents has improved storability of aquatic products due to their antimicrobial properties. Recently, a combination of chitosan and nisin has been proven effective for preservation of Pseudosciaena crocea stored at 4 °C. However, few studies are available on the antimicrobial potential of this combination against Shewanella spp. in Pseudosciaena crocea. In this study the antimicrobial performance of 1% chitosan, 1% chitosan +0.4% nisin and 1% chitosan +0.6% nisin against two isolates Shewanella putrefaciens DHS01 and Shewanella algae DHS02 was compared. The results revealed that with the synergy of 0.6% nisin, 1% chitosan presented significant inhibitory effects on growth and biofilm formation of these two species. By inhibiting growth and biofilm formation of Shewanella putrefaciens and Shewanella algae, this combination was considered capable of reducing amino acids loss of Pseudosciaena crocea and accumulation of spoilage products like VBN, putrescine and cadaverine. Simultaneously, we proposed a new method to monitor the growth of Shewanella putrefaciens and Shewanella algae in Pseudosciaena crocea by analysis of phospholipid acids.