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The evolutionary mechanism and function analysis of two subgroups of histamine-producing and non-histamine-producing
Jinjin Ma1, Yao Nie1, Lijie Zhang1
1Lab of Brewing Microbiology and Applied Enzymology, Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, China.
Abstract:
Tetragenococcus halophilus is a halophilic bacterium that existed in the fermentation of soy sauce and miso for flavor production and probiotic benefits. However, it is composed of two subgroups, histamine-producing and non-histamine-producing, with the former causing histamine accumulation and offering risks to food safety. Exploring the evolutionary mechanisms and physiological function of histamine-biosynthesis is of significance for understanding the formative mechanism of T. halophilus's strain-specificity and is helpful for microbial control. Using systematic genomic analysis, we found that plasmid acquisition and loss is the evolutionary form resulting in the two subgroups of T. halophilus. Two plasmids, plasmid α with 30 kb and plasmid β with 4 kb existed in histamine-producing T. halophilus. We investigated the whole genetic information and proposed their genetic function in both two plasmids. The acquisition of histamine-producing plasmid enhanced the acid tolerance of histamine-producing T. halophilus but did not affect salt tolerance. More interestingly, we found that the existence of plasmid will promote the co-culture growth of T. halophilus. This study deepens our understanding of the formative mechanism of microbial species diversity, and provides our knowledge of the physiological function of histamine-producing plasmids.
Insights
Plasmid acquisition drives the evolution of histamine-producing Tetragenococcus halophilus, impacting food safety and microbial growth. This study reveals how plasmids influence strain diversity and acid tolerance in these important fermentative bacteria.
Area of Science:
- Microbiology
- Food Science
- Genomics
Background:
- Tetragenococcus halophilus is a halophilic bacterium crucial for soy sauce and miso fermentation.
- This species comprises histamine-producing and non-histamine-producing subgroups.
- Histamine accumulation by certain strains poses food safety risks.
Purpose of the Study:
- To investigate the evolutionary mechanisms behind T. halophilus strain-specificity.
- To understand the physiological functions of histamine-biosynthesis in T. halophilus.
- To explore the role of plasmids in the divergence of T. halophilus subgroups.
Main Methods:
- Systematic genomic analysis was employed.
- The genetic information of two plasmids (α and β) in histamine-producing strains was investigated.
- Comparative analysis of histamine-producing and non-histamine-producing strains.
Main Results:
- Plasmid acquisition and loss were identified as the key evolutionary drivers for the two T. halophilus subgroups.
- Histamine-producing strains possess two plasmids (α: 30 kb, β: 4 kb).
- Acquisition of these plasmids enhanced acid tolerance but not salt tolerance, and promoted co-culture growth.
Conclusions:
- Plasmid dynamics are central to the diversification of T. halophilus.
- Histamine-producing plasmids confer specific physiological advantages, influencing strain behavior.
- This research deepens understanding of microbial species diversity and the function of histamine-producing plasmids.
