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Zhang L.,Xihua University | Zhang L.,Sichuan Jiannanchun Group Co. | Li Z.,Xihua University | Dai B.,Xihua University | And 2 more authors.
Acta Biologica Hungarica | Year: 2013

Monascus pigments, which are produced by various species of Monascus, often have been used as a natural colourant and as traditional natural food additives, especially in Southern China, Japan and Southeastern Asia. The limitation of wide using Monascus pigment is attributed to one of its secondary metabolites named citrinin. The aim of this study was to investigate the influence of pigment and citrinin production via submerged fermentation (SmF) and solid-state fermentation (SF) from rice (Oryza sativa L.) by Monascus purpureus AS3.531. The optimal fermentation temperature and pH were significantly different for pigment production through different fermentation mode (35 C, pH 5.0 for SF and 32 C, pH 5.5 for SmF, respectively). Adding 2% (w/v) of glycerol in the medium could enhance the pigment production. On the optimized condition, although the concentration of citrinin produced by SmF (19.02 ug/g) increased more than 100 times than that by SF (0.018 ug/g), the pigment yield by SmF (7.93 U/g/g) could be comparable to that by SF (6.63 U/g/g). Those indicate us that fermentation mode seems to be the primary factor which influence the citrinin yield and secondary factor for pigment production.

Tao Y.,CAS Chengdu Institute of Biology | Rui J.,CAS Chengdu Institute of Biology | Li J.,CAS Chengdu Institute of Biology | Xu Z.,Sichuan Jiannanchun Group Co. | And 4 more authors.
Huagong Xuebao/CIESC Journal | Year: 2014

Pit mud (PM) plays a key role in controlling the quality of Chinese Luzhou-flavor liquor in anaerobic fermentation. Here, microbial community composition and diversity in PM samples using pyrosequencing technique were investigated. A total of 494293 valid sequences were obtained. The reads fell into 796 operational taxonomic units (OTUs) affiliated to 21 phyla. The predominant groups were Firmicutes (66.8% of total reads), Bacteroidetes (16.0%), Euryarchaeota (9.0%), Spirochaetes (2.2%), Actinobacteria (1.8%) and Chloroflexi (1.0%). Microbial diversity increased with cellar age until 25 years old, but kept relatively constant from 25 to 50 years. A large difference between microbial communities was observed in the pit muds with different cellar ages. Lactobacillus predominanted in 1-year pit mud (62.3%), but its abundance decreased remarkably in 10-year and older pit muds. In contrast, the abundances of Petrimonas, Clostridium IV and methanogens increased dramatically. In addition, Archaea in PM were mainly composed of hydrogenotrophic methanogens such as Methanobrevibacter, Methanoculleus, Methanobacterium, while the H2/acetate-utilizing Methanosarcina was more abundant in PM with cellar age of 25-50 years (3.1%-4.5%). This research supports the practical experience that old fermentation pits produce high quality Luzhou-flavor liquor. © All Rights Reserved.

Tao Y.,CAS Chengdu Institute of Biology | Li J.,CAS Chengdu Institute of Biology | Rui J.,CAS Chengdu Institute of Biology | Xu Z.,Sichuan Jiannanchun Group Co. | And 6 more authors.
Applied and Environmental Microbiology | Year: 2014

Chinese strong-flavored liquor (CSFL) accounts for more than 70% of all Chinese liquor production. Microbes in pit mud play key roles in the fermentation cellar for the CSFL production. However, microbial diversity, community structure, and cellar-agerelated changes in pit mud are poorly understood. Here, we investigated the prokaryotic community structure and diversity in pit-mud samples with different cellar ages (1, 10, 25, and 50 years) using the pyrosequencing technique. Results indicated that prokaryotic diversity increased with cellar age until the age reached 25 years and that prokaryotic community structure changed significantly between three cellar ages (1, 10, and 25 years). Significant correlations between prokaryotic communities and environmental variables (pH, NH4+, lactic acid, butyric acid, and caproic acid) were observed. Overall, our study results suggested that the long-term brewing operation shapes unique prokaryotic community structure and diversity as well as pit-mud chemistry. We have proposed a three-phase model to characterize the changes of pit-mud prokaryotic communities. (i) Phase I is an initial domestication period. Pit mud is characterized by abundant Lactobacillus and high lactic acid and low pH levels. (ii) Phase II is a transition period. While Lactobacillus abundance decreases dramatically, that of Bacteroidetes and methanogens increases. (iii) Phase III is a relative mature period. The prokaryotic community shows the highest diversity and capability to produce more caproic acid as a precursor for synthesis of ethyl caproate, the main flavor component in CSFL. This research provides scientific evidence to support the practical experience that old fermentation cellars produce high-quality liquor. © 2014, American Society for Microbiology.

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