In the world of dairy production, the quest for improved fermentation processes and enhanced product quality is an ongoing challenge. Researchers have long sought to understand and manipulate the metabolic pathways of bacteria like Streptococcus thermophilus, a key player in the dairy industry. A recent breakthrough by Jiahui Tai, affiliated with the Key Laboratory of Dairy Biotechnology and Engineering at Inner Mongolia Agricultural University, has shed new light on how this bacterium metabolizes galactose, a sugar that can accumulate in fermented dairy products and affect their quality.
Tai and his team focused on a mutant strain of S. thermophilus, IMAU20551Y, which was previously obtained through N-methyl-N′-nitro-N-nitrosoguanidine (NTG) mutagenesis. This mutant strain exhibited significantly altered enzyme activities related to galactose metabolism compared to the wild type. Specifically, β-galactosidase and galactokinase activities were higher in the mutant, while glucokinase and pyruvate kinase activities were significantly decreased. “The mutant strain showed a remarkable reduction in galactose accumulation,” Tai explained, “which is a critical step towards improving the quality of fermented dairy products.”
To delve deeper into the mechanism behind this enhanced galactose metabolism, the researchers employed a multi-omics approach, combining high-performance liquid chromatography (HPLC) analysis with genomic and transcriptomic data. The HPLC analysis revealed that the mutant strain reduced galactose accumulation in fermented milk by 41.4% compared to the wild type. This finding underscores the potential of the mutant strain in producing low-galactose dairy products, a significant advancement in the field.
Genome sequencing did not reveal any mutations in the gene sequences associated with galactose metabolism. However, transcriptomic data provided crucial insights. The expression of genes galM, galK, galT, and galE, which are involved in the Leloir pathway, was up-regulated in the mutant. Additionally, the LacI family transcriptional regulator GalR was also up-regulated, suggesting a coordinated enhancement of galactose metabolism.
The implications of this research are far-reaching. By understanding the molecular mechanisms behind enhanced galactose metabolism, researchers can pave the way for genetic engineering modifications to create galactose-positive (Gal+) S. thermophilus strains. These strains could be used as starters in the production of low-galactose fermented dairy products, addressing a long-standing issue in the dairy industry.
This study, published in Current Research in Food Science, opens new avenues for genetic engineering and metabolic pathway manipulation in S. thermophilus. As Tai noted, “This research provides a solid foundation for future genetic engineering efforts aimed at improving the metabolic capabilities of S. thermophilus.” The potential commercial impact is substantial, as dairy producers worldwide seek to enhance the quality and nutritional value of their products. The ability to reduce galactose accumulation not only improves product quality but also addresses dietary concerns for individuals with galactose intolerance.
The findings from Tai’s research highlight the power of multi-omics analysis in unraveling complex metabolic processes. As the dairy industry continues to evolve, such insights will be crucial in driving innovation and meeting consumer demands for healthier, more sustainable products. The future of dairy fermentation looks brighter with these advancements, promising a new era of precision and efficiency in the production of fermented dairy products.