Extremely halophilic strains of Halobacterium salinarum as a potential starter culture for fish sauce fermentation

Abstract

Proteinase-producing halophilic archaea were isolated from Thai fish sauce collected from industrial fermentation tanks at various periods of fermentation. Five isolates namely, J-1-S4, J-1-S13, J-1-S22, 2 m-40-15-R2, and P-1-S8, were identified as Halobacterium salinarum with slightly different colony and morphological characteristics among isolates. Starters of five isolates were prepared and added to the anchovy mixed with 25% solar salt and fermented for 180 days at 30-35 • C. Halophilic bacteria/archaea counts of inoculated samples were decreased and undetected after 120 days of fermentation. At 180 days of fermentation, α-amino group contents of inoculated fish sauce samples (856-1010 mM) and total nitrogen content (2.2%-2.5%) were higher than the control without archaea inoculation (p < 0.05). All samples contained low amounts of biogenic amines, suggesting that all starters were not biogenic amine formers. The major volatile compound found in samples inoculated with H. salinarum P-1-S8 and H. salinarum 2 m-40-15-R2 was 3-methylbutanal, which contributes to the meaty note.Dimethyl disulfide, a compound that contributes to fecal note, was detected in all inoculated samples in a lower amount than in the commercial fish sauce (p < 0.05). Thus, H. salinarum accelerated protein hydrolysis and produced desirable volatile compounds during fish sauce fermentation in a strain-specific manner.

Comparative Genomics of Halobacterium salinarum Strains Isolated from Salted Foods Reveals Protechnological Genes for Food Applications

“…However, up to date, no phenotypic evidence of H. salinarum biogenic amine production in food has been highlighted. On the contrary, a previous study detected a reduced or unaltered histamine content during the fermentation of salted anchovies and fish sauce inoculated with H. salinarum , suggesting a microbial competition of the species with other histamine-producing microorganisms [ 50 , 80 ].…”

“…For instance, they have been widely used as debittering agents and for protein hydrolysate preparation in the food industry [ 48 ]. Moreover, their importance has also been reported in the processing of dry-salted fish [ 49 ], indicating that halophilic starter cultures can be exploited to increase the free amino acid content, improving the aroma characteristics [ 50 ].…”