A Lactobacillus strain named SMF-L5 from traditional fermented mandarin fish was isolated using MRS medium with bromocresol green and identified as Lactobacillus sakei by morphological, physiological and biochemical assays and 16S rDNA sequence analysis. L. sakei SMF-L5 grew well in MRS liquid medium, entered the stable growth period after 14 h, and produced the highest viable cell count of 7.0 × 10⁹ CFU/mL. The production of lactic acid of the strain was 10 g/L after 24 h cultivation. The optimal culture conditions were as follows: culture temperature 30.9 ℃, initial pH 6.15 and inoculum amount 1.94%. Strain SMF-L5 had tolerance to 0.08 g/mL NaCl, and obvious inhibitory effects on Escherichia coli, Staphylococcus aureus. The fermented mandarin fish inoculated with L. sakei SMF-L5 had superior color, texture and flavor than spontaneously fermented mandarin fish. These results showed that L. sakei SMF-L5 has the potential for application as an excellent starter in the industrial production of smelly mandarin fish.

We undertook this work in order to study the correlation between the microbial community composition and the characteristic flavor substances in stinky mandarin fish during the low-temperature fermentation process. 16S rDNA high-throughput sequencing was used to determine the microbial community composition. Gas chromatography-mass spectrometry (GC-MS) was used to evaluate the volatile flavor substances, and the characteristic flavor substances were identified by multivariate statistical analysis combined with odor activity value (OAV). The correlation between the microbial flora and the characteristic flavor substances was analyzed by Spearman correlation analysis. The results showed that Lactobacillus sakei, Hafnia alvei and Serratia plymuthica were the dominant microorganisms during the low-temperature fermentation process. A total of 81 volatile flavor substances were detected, and the characteristic flavor substances identified included 1-octen-3-ol, eucalyptol, linalool, hexanal, heptanal, nonanal, trimethylamine, D-limonene, and o-cymene. L. sakei showed a significant positive correlation with linalool and o-cymene (P < 0.05). H. alvei and S. plymuthica were significantly positively correlated (P < 0.05) with the aroma substances D-limonene and linalool as well as the odorous substance trimethylamine (P < 0.05). The results provide a theoretical basis for developing functional starters and regulating the flavor quality of stinky mandarin fish.