# Exploration of yeast biodiversity from Thai flowers and optimization of carotenoid production by a promising isolate

## TL;DR

A red yeast strain from Thai flowers was found to produce high levels of carotenoids, which could be useful for industrial applications.

## Contribution

A novel yeast strain, Rhodotorula paludigena SWU-FKT03, was identified and optimized for high carotenoid production.

## Key findings

- Rhodotorula paludigena SWU-FKT03 produced 183.30 mg/L of carotenoids under standard conditions.
- Optimized conditions increased carotenoid production to 288.27 mg/L using glucose and monosodium glutamate.
- The optimized strain showed a three-fold increase in carotenoid yield in shaking flasks.

## Abstract

Microbial synthesis of carotenoids has garnered significant attention as an eco-friendly alternative to conventional synthetic methods and its facile extraction for impressive yield. This study delves into the efficacy of carotenoid production from a red yeast strain, as well as the biodiversity of yeast species from Thai flowers. The research involved the collection of flower samples within Thailand, along with 12 yeast species from 10 genera of Ascomycetes and 4 genera of Basidiomycetes which were isolated by identifying the D1/D2 domain of the large subunit rRNA gene. Unexpectedly, Rhodotorula paludigena SWU-FKT03 emerged as the top performing yeast strain, boasting an impressive carotenoid production rate of 183.30 ± 5.00 mg/L among the 36 red yeast strains isolated. Subsequently, a further investigation was performed, focusing on optimized culture conditions for carotenoid production from this yeast strain. The results were promising, as carotenoid production surged to 288.27 mg/L when 20 g/L of glucose and 10 g/L of monosodium glutamate served as the carbon and nitrogen sources, respectively. These findings underscore the potential of the R. paludigena SWU-FKT03 as a high-yield carotenoid producer when cultivated in shaking flasks, exhibiting a three-fold increase in carotenoid content when under optimized conditions. These results hint at the potential of this approach for future large-scale carotenoid production.

One-sentence summary A novel red yeast, Rhodotorula paludigena SWU-FKT03, isolated from Thai floral ecosystems, demonstrated high-yield carotenoid production of 288.27 mg/L after fermentation optimization, establishing a significant potential for industrial applications.

Graphical Abstract