Development of a Novel Restrictive Medium for Monascus Enrichment From Hongqu Based on the Synergistic Stress of Lactic Acid and Ethanol
Graphical Abstract The restrictive medium containing lactic acid and ethanol enabled the enrichment of Monascus sp. Hongqu is a famous fermented food produced by Monascus and has been used as food coloring, wine starters and food additives for thousands of years in China. Excellent Monascus strain i...
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Published in | Frontiers in microbiology Vol. 12; p. 702951 |
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Main Authors | , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Frontiers Media S.A
21.06.2021
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Subjects | |
Online Access | Get full text |
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Summary: | Graphical Abstract
The restrictive medium containing lactic acid and ethanol enabled the enrichment of
Monascus
sp.
Hongqu is a famous fermented food produced by
Monascus
and has been used as food coloring, wine starters and food additives for thousands of years in China. Excellent
Monascus
strain is an important prerequisite for producing high-quality Hongqu. However, the isolation of
Monascus
pure culture from Hongqu samples is time-consuming and laborious because it is easily interfered by other microorganisms (especially filamentous fungi). Therefore, the development of restrictive medium for
Monascus
enrichment from Hongqu is of great significance for the preparation and screening of excellent
Monascus
strains. Results of this study showed that
Monascus
has good tolerance to lactic acid and ethanol. Under the conditions of tolerance limits [7.5% lactic acid (v/v) and 12.0% ethanol (v/v)],
Monascus
could not grow but it still retained the vitality of spore germination, and the spore activity gradually decreased with the increasing concentrations of lactic acid and ethanol. More interestingly, the addition of lactic acid and ethanol significantly changed the microbial community structure in rice milk inoculated with Hongqu. After response surface optimization,
Monascus
could be successfully enriched without the interference of other microorganisms when 3.98% (v/v) lactic acid and 6.24% (v/v) ethanol were added to rice milk simultaneously. The optimal enrichment duration of
Monascus
by the restrictive medium based on the synergistic stress of lactic acid and ethanol is 8∼24 h. The synergistic stress of lactic acid and ethanol had no obvious effects on the accumulation of major metabolites in the progeny of
Monascus
, and was suitable for the enrichment of
Monascus
from different types of Hongqu. Finally, the possible mechanisms on the tolerance of
Monascus
to the synergistic stress of lactic acid and ethanol were preliminarily studied. Under the synergistic stress of lactic acid and ethanol, the cell membrane of
Monascus
defends against lactic acid and ethanol into cells to some extent, and the superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities of
Monascus
were higher than those of other fungi, which significantly reduced the degree of lipid peroxidation of cell membrane, while secreting more amylase to make reducing sugars to provide the cells with enough energy to resist environmental stress. This work has great application value for the construction of
Monascus
strain library and the better development of its germplasm resources. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 This article was submitted to Food Microbiology, a section of the journal Frontiers in Microbiology Edited by: Van-Tuan Tran, Vietnam National University, Hanoi, Vietnam Reviewed by: Zhilong Wang, Shanghai Jiao Tong University, China; Chan Zhang, Beijing Technology and Business University, China; Yanping Li, Nanchang University, China |
ISSN: | 1664-302X 1664-302X |
DOI: | 10.3389/fmicb.2021.702951 |