APPLIED AND ENVIRONMENTAL MICROBIOLOGY
·
2020
·Vol. 86
·期 17
·
IF 4.016
Ting Yang,Ya-Hui Shao,Li-Zhong Guo,Xiang-Lin Meng,Hao Yu,Wei-Dong Lu
Chromohalobacter salexigens DSM 3043 can grow on N,N-dimethylglycine (DMG) as the sole C, N, and energy source and utilize sarcosine as the sole N source under aerobic conditions. However, little is known about the genes and enzymes involved in the conversion of DMG to sarcosine in this strain. In the present study, gene disruption and complementation assays indicated that the csal_0990, csal_0991, csal_0992, and csal_0993 genes are responsible for DMG degradation to sarcosine. The csal_0990 gene heterologously expressed in Escherichia coli was proven to encode an unusual DMG dehydrogenase (DMGDH). The enzyme, existing as a monomer of 79 kDa with a noncovalently bound flavin adenine dinucleotide, utilized both DMG and sarcosine as substrates and exhibited dual coenzyme specificity, preferring NAD+ to NADP+. The optimum pH and temperature of enzyme activity were determined to be 7.0 and 60°C, respectively. Kinetic parameters of the enzyme toward its substrates were determined accordingly. Under high-salinity conditions, the presence of DMG inhibited growth of the wild type and induced the production and accumulation of trehalose and glucosylglycerate intracellularly. Moreover, exogenous addition of DMG significantly improved the growth rates of the four DMG– mutants (Δcsal_0990, Δcsal_0991, Δcsal_0992, and Δcsal_0993) incubated at 37°C in S-M63 synthetic medium with sarcosine as the sole N source. 13C nuclear magnetic resonance (13C-NMR) experiments revealed that not only ectoine, glutamate, and N-acetyl-2,4-diaminobutyrate but also glycine betaine (GB), DMG, sarcosine, trehalose, and glucosylglycerate are accumulated intracellularly in the four mutants.IMPORTANCE Although N,N-dimethylglycine (DMG) dehydrogenase (DMGDH) activity was detected in cell extracts of microorganisms, the genes encoding microbial DMGDHs have not been determined until now. In addition, to our knowledge, the physiological role of DMG in moderate halophiles has never been investigated. In this study, we identified the genes involved in DMG degradation to sarcosine, characterized an unusual DMGDH, and investigated the role of DMG in Chromohalobacter salexigens DSM 3043 and its mutants. Our results suggested that the conversion of DMG to sarcosine is accompanied by intramolecular delivery of electrons in DMGDH and intermolecular electron transfer between DMGDH and other electron acceptors. Moreover, an unidentified methyltransferase catalyzing the production of glycine betaine (GB) from DMG but sharing no homology with the reported sarcosine DMG methyltransferases was predicted to be present in the cells. The results of this study expand our understanding of the physiological role of DMG and its catabolism to sarcosine in C. salexigens.
研究领域:
微生物学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FOOD CHEMISTRY
·
2022
·
IF 9.231
Jing Yu,Kuan Lu,Jiwei Zi,Xihong Yang,Zuoxing Zheng,Wancui Xie
Retaining the traditional flavor while shortening the fermentation cycle is the current research focus for shrimp paste fermentation technology. The present study investigated the effect of combined use of halophilic bacteria as starters on the sensory and flavor characteristics of rapidly fermented shrimp paste. Sensory evaluation indicated that the starter-inoculated samples had high texture, appearance, and overall quality scores. Headspace gas chromatography-ion mobility spectrometry/mass spectrometry (HS-GC-IMS/MS) identified 95 volatile compounds, the fingerprint profiles of the starter-inoculated samples were similar to those of the traditional sample. Notably, the content of benzaldehyde, phenylethylaldehyde, and 3-methylbutyraldehyde increased significantly in the starter-inoculated samples ( p < 0.05), which may provide an intense malt, caramel, and pleasant odor. Although the content of certain flavor substances in the starter-inoculated samples was lower than those of traditional sample, the use significantly reduced the fermentation time and mimicked the flavor profile of traditional shrimp paste to some extent.
研究领域:
食品科学
·
微生物学
✓ 已验证
DOI
PubMed
高影响因子
Frontiers in Microbiology
·
2021
·
IF 5.64
Zhang Jianming,Zhang Chengcheng,Xin Xiaoting,Liu Daqun,Zhang Wenwu
Differences in flavor compounds and bacterial communities of Xuecai by traditional and modern fermentation are poorly understood. Allyl isothiocyanate (E9), ethyl acetate (E1), 3-butenenitrile (N1), phenol (P1), ethanol (A1), and 3-(2,6,6-trimethyl-1-cyclohexen-1-yl) acrylaldehyde (L11) were the main flavor compounds that differed between Xuecai produced by traditional and modern fermentation. Among these compounds, the contents of N1 and E9 were higher in modern fermentation Xuecai. Traditional fermentation Xuecai possessed higher contents of A1, P1, E1, and L11. High-throughput sequencing showed that Lactobacillus-related genera was the most abundant genus (50%) in modern fermentation Xuecai. However, in traditional fermentation Xuecai, Halanaerobium (29.06%) and Halomonas (12.96%) were the dominant genera. Halophilic bacteria (HB) positively contribute to the flavor of Xuecai. Carbohydrate metabolism and amino acid metabolism were the most abundant pathways associated with the bacterial communities of the Xuecai. This indicated that Xuecai flavor formation is mainly dependent on protein and carbohydrate degradation. This study provides a novel insight that HB may be important for flavor formation of Xuecai.
研究领域:
食品科学
·
微生物学
✓ 已验证
DOI
高影响因子
WATER SCIENCE AND TECHNOLOGY
·
2021
·Vol. 83
·期 9
·2160-2168
·
IF 1.915
Feng Kaiqing,Zhang Jiandong,Gao Lili,Tian Qi
Alicyclic amines are widely used in several types of industries, and considerable attention has been devoted to possible environmental pollution by alicyclic amines in hypersaline industrial wastewater. In this study, a new hypersaline tolerant bacterial TYUT067 capable of growing in liquid basal salt medium with cyclohexylamine (CHAM) as the sole carbon source and energy source, was isolated from soil, and discovered with highly efficient CHAM degrading ability. The strain TYUT067 was identified as Paenarthrobacter sp. based on 16S rDNA gene sequence, and its degradation characteristic was examined. The results revealed that the isolated TYUT067 could grow well under pH range of 6.5–10.0, temperature from 20 °C to 30 °C. For degradation of 60 mM of cyclohexylamine, 100% degradation could be finished within 120 h. The TYUT067 could degrade 10 mM CHAM under hypersaline conditions (3–5% NaCl, w/v), revealed the hypersaline tolerance of TYUT067. Different type of amines was also tested with TYUT067, the degradations of >90% were achieved toward several alicyclic amines. The current results suggested that TYUT067 was a potential species could be efficiently used for the degradation of alicyclic amines and might be applicable to a hypersaline wastewater treatment system for the removal of alicyclic amines. A new cyclohexylamine degradation bacterial strain TYUT067 was isolated from soil environment. The isolated TYUT067 is an alkali-tolerant strain and mesophilic microorganisms. The isolated TYUT067 can degrade CHAM under hypersaline environment. The isolated TYUT067 can degrade various alicyclic amines.
研究领域:
环境微生物学
·
环境工程
·
生物降解
·
工业废水处理
·
污染生态学
✓ 已验证
DOI
高影响因子
PLoS One
·
2018
·Vol. 13
·期 10
·e0204324
·
IF 2.766
Fangfang Li,Yidan Liu,Diwei Wang,Chaosheng Zhang,Zhihui Yang,Siqi Lu,Yangyang Wang
A halotolerant bacterial consortium capable of degrading di-(2-ethylhexyl) phthalate (DEHP) was enriched from activated sludge. Community analysis revealed that LF contained seven families and seven genera of bacteria. The predominant species was Gordonia sp. (54.93%), Rhodococcus . sp. (9.92%) and Achromobacter sp. (8.47%). The consortium could degrade 93.84% of 1000 mg/l DEHP after 48 h incubation. The optimal temperature and pH for LF to degrade DEHP were 30 °C and 6.0, respectively. LF degraded more than 91% of DEHP with salt concentrations ranging from 0–3%. The inoculum size had great effects on DEHP degradation (incubation time < 24h). LF could degrade high concentrations of DEHP (from 100 to 2000 mg/l) with the degradation ratio above 92% after 72 h incubation. Kinetics analysis revealed that the degradation of DEHP by LF was best fitted by the first-order kinetics when the initial concentration ranged from 100 to 2000 mg/l. The main intermediates (2-ethylhexyl pentyl phthalate, butyl (2-ethylhexyl) phthalate (BEHP), mono-ethylhexyl phthalate (MEHP), mono-hexyl phthalate (MHP), mono-butyl phthalate (MBP)) in DEHP degradation process were identified using gas chromatography–mass spectrometry (GC-MS), and a new complex biochemical pathway was proposed. Furthermore, LF could also degrade dimethyl phthalate (DMP), diethyl phthalate (DEP), di- n -butyl phthalate (DBP), di- n -octyl phthalate (DOP) and phthalic acid (PA).
研究领域:
环境科学
·
微生物学
✓ 已验证
DOI
高影响因子
FOOD RESEARCH INTERNATIONAL
·
2021
·
IF 6.475
Daqun Liu,Chengcheng Zhang,Jianming Zhang,Xiaoting Xin,Xiaojun Liao
Fermented vegetable flavors are closely associated with microbial metabolism. Here, shifts in flavor metabolites and their correlations to the structure and function of fermentative microbial communities were explored during the spontaneous fermentation process of potherb mustard ( Brassica juncea var. multiceps ), a traditionally fermented vegetable from China. Halophilic bacteria (HAB, i.e. , Halomonas , Salinivibrio , and Vibrio ) and lactic acid bacteria (LAB, i.e. , Lactobacillus -related genera and Weissella ) became highly abundant after potherb mustard fermentation. Further, HAB and LAB abundances exhibited significant, positive correlations with metabolites important in fermented potherb mustard flavoring (e.g., organic acids, amino acids, alcohols, aldehydes, and nitriles). Metagenomic analysis indicated that Halomonas , Salinivibrio , Weissella , and Lactobacillus -related genera were likely actively engaged in pyruvate metabolism (ko00620) and citrate cycle (TCA cycle, ko00020), leading to higher lactic and acetic acid concentrations, along with lower pH, which would affect levels of volatile isothiocyanates and nitriles that contribute to flavoring of fermented potherb mustard. Further, HAB and LAB were the primary populations inferred to be responsible for amino acid and fatty acid metabolism in addition to the biosynthesis of numerous volatile flavor compounds. This study highlights the predominance and importance of LAB and HAB during spontaneous fermentation of potherb mustard and provides new insights into their roles in this process.
研究领域:
微生物学
·
食品科学
·
代谢组学
✓ 已验证
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY
·
2021
·
IF 5.277
Chengcheng Zhang,Jianming Zhang,Daqun Liu
Zhacai is a traditional fermented vegetable that has been consumed in China for centuries. It is currently manufactured by spontaneous fermentation and therefore mostly relies on the activities of autochthonous microorganisms. Here, we characterized microbial community dynamics and associated biochemical changes in 12% salted Zhacai during a 90-day spontaneous fermentation process using high-throughput sequencing and chromatography-based approaches to identify associations between microorganisms and fermentation characteristics. Amplicon sequencing targeting bacterial 16S rRNA genes revealed that bacterial communities were dominated by halophilic bacteria (HAB, i.e., Halomonas and Idiomarina ) and lactic acid bacteria (LAB, i.e., Lactobacillus -related genera and Weissella ) after 30 days of fermentation. In addition, the relative abundances of the fungal genera Debaryomyces , Sterigmatomyces , and Sporidiobolus increased as fermentation progressed. Concomitantly, pH decreased while titratable acidity increased during fermentation, along with associated variation in biochemical profiles. Overall, the levels of organic acids (i.e., lactic and acetic acid), free amino acids (i.e., alanine, lysine, and glutamic acid), and volatiles (i.e., alcohols, esters, aldehydes, and ketones) increased in mature Zhacai. In addition, the abundances of Lactobacillus -related species, Halomonas spp., Idiomarina loihiensis , as well as that of the yeast Debaryomyces hansenii , were strongly correlated with increased concentrations of organic acids, amino acids, biogenic amines, and volatiles. This study provides new detailed insights into the succession of microbial communities and their potential roles in Zhacai fermentation.
研究领域:
食品科学
·
微生物学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）