Bacterial communities in fish sauce mash using culture-dependent and -independent methods

Abstract

In fish sauce production, microorganisms are associated with the fermentation process; however, the sequential changes in the bacterial communities have never been examined throughout the period of fermentation. In this study, we determined the bacterial floras in a fish sauce mash over 8 months, using three different culture media and 16S rRNA gene clone library analysis. During the first 4 weeks, viable counts of non-halophilic and halophilic bacteria decreased and were dominated by Staphylococcus species. Between 4 and 6 weeks, halophilic and highly halophilic bacterial counts markedly increased from 10(7) to 10(8) cfu/g, and the predominant species changed to Tetragenococcus halophilus. The occurrence of T. halophilus was associated with an increase of lactic acid and a reduction of pH values. In contrast, non-halophilic bacterial counts decreased to 10(6) cfu/g by 6 weeks with Bacillus subtilis as the dominant isolate. Clone library analysis revealed that the dominant bacterial group also changed from Staphylococcus spp. to T. halophilus, and the changes were consistent with those of the floras of halophilic and highly halophilic isolates. This is the first report describing a combination approach of culture and clone library methods for the analysis of bacterial communities in fish sauce mash.

Bacterial community dynamics and metabolite changes in myeolchi-aekjeot, a Korean traditional fermented fish sauce, during fermentation

“…The naturally occurring fermentation of fish sauces without starter cultures leads to the growth of various halophilic or halotolerant microbes due to their high salt conditions (Fukui et al, 2012;Udomsil et al, 2010). So far, various bacteria including Achromobacter, Bacillus, Halomonas, Micrococcus, Brevibacterium, Halobacterium, Vibrio, Flavobacterium, Staphylococcus, and Tetragenococcus species have been identified in fish sauces by mainly culture-dependent approaches despite the presence of many uncultivable microbes (Fukui et al, 2012;Guan et al, 2011;Lopetcharat et al, 2001;Taira et al, 2007).…”

“…So far, various bacteria including Achromobacter, Bacillus, Halomonas, Micrococcus, Brevibacterium, Halobacterium, Vibrio, Flavobacterium, Staphylococcus, and Tetragenococcus species have been identified in fish sauces by mainly culture-dependent approaches despite the presence of many uncultivable microbes (Fukui et al, 2012;Guan et al, 2011;Lopetcharat et al, 2001;Taira et al, 2007). Culture-independent approaches based on clonal analysis of 16S rRNA genes have been also applied to investigations of microbial communities of fish sauces (Chuon et al, 2014;Kim and Park, 2014), but these approaches have limitations in ascertaining microbial community dynamics during fermentation as they tend to be time-consuming, laborious, and hence relatively low throughput.…”

“…Fish sauces are clear brown liquids with a salty taste and a distinctive fish flavor that are generally made by spontaneous long-term fermentation (more than 6 months) of salted whole small fish (e.g., anchovy and sand eel) (Fukui et al, 2012;Lopetcharat et al, 2001). Myeolchi-aekjeot (MA), a Korean traditional fermented fish sauce, is made by a long-term fermentation of salted anchovies.…”

Genomic characterization of a temperate phage of the psychrotolerant deep-sea bacterium Aurantimonas sp.

“…Genomic DNA was extracted from the isolates according to the method of Fukui et al (2012). The 16S rRNA gene was amplified by PCR using the primers 27F (5 0 -AGA GTT TGA TCC TGG CTC AG-3 0 ) and 1492R (5 0 -GGT TAC CTT GTT ACG ACT T-3 0 ) and the extracted genomic DNA (Delong 1992).…”

Identification and genomic analysis of temperate Pseudomonas bacteriophage PstS-1 from the Japan trench at a depth of 7000 m

“…Genomic DNA was extracted from the isolates grown in marine broth 2216 (MB medium; Difco) according to the method described by Fukui et al [43]. A nearly complete 16S rRNA gene was amplified via PCR using the primers 27F (5 0 -AGA GTT TGA TCC TGG CTC AG-3 0 ) and 1492R (5 0 -GGT TAC CTT GTT ACG ACT T-3 0 ) [44].…”