# The impacts of nicotinamide and inositol on the available cells and product performance of industrial baker's yeasts

## TL;DR

This study shows that adding nicotinamide and inositol improves baker's yeast performance by boosting growth, enzyme activity, and leavening ability.

## Contribution

The novel finding is that adjusting nicotinamide and inositol levels in media enhances yeast performance through metabolic and genetic pathways.

## Key findings

- Nicotinamide and inositol enhance cell growth, trehalose accumulation, and leavening performance in baker's yeast strains.
- Moderate nicotinamide and inositol levels promote enzyme activity and gene transcription related to longevity and metabolism.
- Adjusting inositol-to-choline ratios improves phospholipid composition and reduces inositol inhibition in certain media.

## Abstract

A suitable nutrient supply, especially of vitamins, is very significant for the deep display of the inherent genetic properties of microorganisms. Here, using the chemically defined minimal medium (MM) for yeast, nicotinamide and inositol were confirmed to be more beneficial for the performance of two industrial baker's yeasts, a conventional and a high-sugar-tolerant strain. Increasing nicotinamide or inositol to proper levels could enhance the both strains on cell growth and activity and product performance, including trehalose accumulation and leavening performance. The activity of key enzymes (PCK, TPS) and the content of intermediate metabolites (G6P, UDPG) in the trehalose synthesis pathway were promoted by a moderate supply of nicotinamide and inositol. That were also proved that an appropriate amount of niacinamide promoted the transcription of longevity-related genes (PNC1, SIR2), and the proper concentration of inositol altered the phospholipid composition in cells, namely, phosphatidylinositol and phosphatidyl choline. Furthermore, the cell growth and the leavening performance of the both strains were promoted after adjusting inositol to choline to the proper ratio, resulting directly in content changes of phosphatidylinositol and phosphatidyl choline in the cells. While the two strains responded to the different proper ratio of inositol to choline probably due to their specific physiological characteristics. Such beneficial effects of increased nicotinamide levels were confirmed in natural media, molasses and corn starch hydrolyzed sugar media. Meanwhile, such adjustment of inositol to choline ratio could lessen the inhibition of excess inositol on cell growth of the two tested strains in corn starch hydrolyzed sugar media. However, in molasse, such phenomenon was not observed probably since there was higher Ca2+ in it. The results indicated that the effects of nutrient factors, such as vitamins, on cell growth and other properties found out from the simple chemically defined minimal medium were an effective measure to use in improving the recipe of natural media at least for baker's yeast.

The online version contains supplementary material available at 10.1186/s40643-023-00661-4.