A Novel Approach to Develop Lager Yeast with Higher NADH Availability to Improve the Flavor Stability of Industrial Beer

Abstract

Flavor stability is important for beer quality and extensive efforts have been undertaken to improve this. In our previous work, we proved a concept whereby metabolic engineering lager yeast with increased cellular nicotinamide adenine dinucleotide hydride (NADH) availability could enhance the flavor stability of beer. However, the method for breeding non-genetically modified strains with higher NADH levels remains unsolved. In the current study, we reported a novel approach to develop such strains based on atmospheric and room temperature plasma (ARTP) mutagenesis coupled with 2,4-dinitrophenol (DNP) selection. As a result, we obtained a serial of strains with higher NADH levels as well as improved flavor stability. For screening an optimal strain with industrial application potential, we examined the other fermentation characteristics of the mutants and ultimately obtained the optimal strain, YDR-63. The overall fermentation performance of the strain YDR-63 in pilot-scale fermentation was similar to that of the parental strain YJ-002, but the acetaldehyde production was decreased by 53.7% and the resistance staling value of beer was improved by 99.8%. The forced beer aging assay further demonstrated that the favor stability was indeed improved as the contents of 5-hydroxymethylfurfural in YDR-63 was less than that in YJ-002 and the sensory notes of staling was weaker in YDR-63. We also employed this novel approach to another industrial strain, M14, and succeeded in improving its flavor stability. All the findings demonstrated the efficiency and versatility of this new approach in developing strains with improved flavor stability for the beer industry.

Application of Atmospheric and Room-Temperature Plasma (ARTP) to Microbial Breeding

“…ARTP technology has significantly contributed to the improvement and screening of yeast strains. It has proven effective in producing various yeast mutants with specific traits, such as high-yield yeast [ 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 ], salt-tolerant yeast [ 77 , 78 ], and acid-tolerant yeast [ 79 ], among others ( Table 2 ). Saccharomyces cerevisiae , a well-known yeast species, holds immense importance in industries like winemaking, baking, and brewing, with a historical significance dating back to ancient times [ 80 ].…”

Rapid Screening of High-Yield Gellan Gum Mutants of Sphingomonas paucimobilis ATCC 31461 by Combining Atmospheric and Room Temperature Plasma Mutation with Near-Infrared Spectroscopy Monitoring

“…Li et al [ 8 ] proved that ampicillin, as a stressor and a mutagen, improved exopolysaccharides productivity and viscosity of S. paucimobilis ATCC 31461. In recent years, atmospheric and room temperature plasma (ARTP) mutation technology emerged as a new mutation breeding technology, which has been successfully applied in microorganisms [ 9 , 10 , 11 , 12 , 13 ]. Xu et al [ 10 ] combined ARTP mutagenesis with 2,4-dinitrophenol (DNP) selection to develop lager yeast and obtained a series of mutant strains with higher NADH levels as well as improved flavor stability.…”

“…In recent years, atmospheric and room temperature plasma (ARTP) mutation technology emerged as a new mutation breeding technology, which has been successfully applied in microorganisms [ 9 , 10 , 11 , 12 , 13 ]. Xu et al [ 10 ] combined ARTP mutagenesis with 2,4-dinitrophenol (DNP) selection to develop lager yeast and obtained a series of mutant strains with higher NADH levels as well as improved flavor stability. Nyabako et al [ 11 ] used ARTP mutation coupled with adaptive laboratory evolution (ALE) to improve the acid tolerance of lactobacillus acidophilus and obtained the mutant strain LAartp-ale2 with increased lactic acid stress tolerance.…”