Summary auto-generated
This study describes the identification and characterization of 11 new moderately halophilic lactic acid bacterial strains isolated from fermented squid liver sauce. These gram-positive, tetrad-forming cocci were initially thought to be Tetragenococcus halophilus but were distinguished by several key characteristics: production of histamine from L-histidine, inability to ferment L-arabinose, capability to grow at 40°C, and distinct 16S rRNA gene sequences. Comprehensive molecular and phenotypic analyses, including DNA-DNA hybridization experiments showing less than 50% relatedness to authentic T. halophilus strains, confirmed these isolates represent a new species. The bacteria are facultatively anaerobic, homofermentative lactic acid producers with a DNA G+C content of 36.5 mol% and can tolerate sodium chloride concentrations from 1-25%, with optimal growth at 7-10% NaCl. Based on phylogenetic analysis and DNA reassociation data, the authors propose the name Tetragenococcus muriaticus for this new species, designating strain X-1 (JCM 10006) as the type strain.
Key findings
- Tetragenococcus muriaticus is a new moderately halophilic lactic acid bacterium species isolated from fermented squid liver sauce, distinct from T. halophilus by histamine production, L-arabinose non-fermentation, and 40°C growth capability
- 16S rRNA gene sequence analysis shows the new isolates cluster separately from T. halophilus with an evolutionary distance sufficient to designate them as a different species
- DNA-DNA hybridization experiments revealed less than 50% relatedness between T. muriaticus and T. halophilus strains, confirming species-level separation according to bacterial systematics criteria
- The new species exhibits homofermentative lactic acid production, requires sodium chloride for growth (optimal 7-10%), and produces histamine from L-histidine, with DNA G+C content of 36.5 mol%
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Abstract
A total of 11 strains of moderately halophilic histamine-producing bacteria isolated from fermented squid liver sauce were studied phenotypically, genotypically, and phylogenetically. These strains are considered members of the genus Tetragenococcus based on their physiological, morphological, and chemotaxonomic characteristics. A 16S rRNA gene sequence analysis showed that these strains clustered with, but were separate from, Tetragenococcus halophilus. The results of DNA- DNA hybridization experiments indicated that the new isolates represent a new Tetragenococcus species, for which we propose the name Tetragenococcus muriaticus; strain X-1 (= JCM 10006) is the type strain of this species.