INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY
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2016
·
IF 3.445
Faizan A. Sadiq,Yun Li,TongJie Liu,Steve Flint,Guohua Zhang,Lei Yuan,Zhipeng Pei,GuoQing He
The propensity for aerobic bacilli and allied genera to produce highly heat-resistant spores and thermally stable spoilage enzymes are major bacteriological issues faced by the dairy industry. Most of the enzymes are able to survive any heat treatment applied during the manufacture of milk powders and have the potential to remain active in milk powders and other dairy products during storage, and may explain some of the sensory and functionality defects reported in dairy products . Despite many reports on the occurrence of spore-forming bacteria in dairy products, knowledge about food quality related properties of many aerobic sporeformers is still scarce. Therefore, the aim of this study was to determine thermal resistance and spoilage potential of a large pool of mesophilic and thermophilic sporeformers, representing 738 isolates and 31 different RAPD groups, recently isolated from Chinese milk powders. Spore formers producing highly heat resistant spores (surviving 125 °C for 30 min) included 2 thermophiles ( Geobacillus thermoleovorans group and Geobacillus stearothermophilus ) and one mesophilic species ( Brevibacillus brevis ). Paenibacillus macerans showed the highest proteolytic activity followed by members of the Bacillus cereus group, Br. brevis , Bacillus subtilis , G. thermoleovorans group and Virgibacillus proomii . The highest lipase producing strains belonged to Bacillus licheniformis . Phospholipase activity was only shown by members of the B. cereus group and Brevibacillus parabrevis . Ten strains showed positive β -galactosidase activity, while, 4 strains showed positive haemolytic activity. B. licheniformis strains, despite belonging to one RAPD group or sub-group showed markedly different phenotypic characters which support the previous findings of heterogeneity in RAPD-based B. licheniformis groups. The results of this study will broaden the knowledge about the spoilage potential and thermal resistance of many strains of dairy origin.
研究领域:
食品科学
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微生物学
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产品关联
DOI
PubMed
高影响因子
APPLIED AND ENVIRONMENTAL MICROBIOLOGY
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2014
·Vol. 80
·期 8
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IF 3.952
Kundi Zhang,Xiaohua Chen,Wolfgang H. Schwarz,Fuli Li
Two cellulolytic thermophilic bacterial strains, CS-3-2 and CS-4-4, were isolated from decayed cornstalk by the addition of growth-supporting factors to the medium. According to 16S rRNA gene-sequencing results, these strains belonged to the genus Clostridium and showed 98.87% and 98.86% identity with Clostridium stercorarium subsp. leptospartum ATCC 35414T and Clostridium cellulosi AS 1.1777T, respectively. The endoglucanase and exoglucanase activities of strain CS-4-4 were approximately 3 to 5 times those of strain CS-3-2, whereas the β-glucosidase activity of strain CS-3-2 was 18 times higher than that of strain CS-4-4. The xylanase activity of strain CS-3-2 was 9 times that of strain CS-4-4, whereas the β-xylosidase activity of strain CS-4-4 was 27 times that of strain CS-3-2. The enzyme activities in spent cultures following cocultivation of the two strains with cornstalk as the substrate were much greater than those in pure cultures or an artificial mixture of samples, indicating synergism of glycoside hydrolase secretomes between the two strains. Quantitative measurement of the two strains in the cocultivation system indicated that strain CS-3-2 grew robustly during the initial stages, whereas strain CS-4-4 dominated the system in the late-exponential phase. Liquid chromatography-tandem mass spectrometry analysis of protein bands appearing in the native zymograms showed that ORF3880 and ORF3883 from strain CS-4-4 played key roles in the lignocellulose degradation process. Both these open reading frames (ORFs) exhibited endoglucanase and xylanase activities, but ORF3880 showed tighter adhesion to insoluble substrates at 4, 25, and 60°C owing to its five carbohydrate-binding modules (CBMs).
研究领域:
微生物学
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生物化学
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DOI
PubMed
高影响因子
GEOCHIMICA ET COSMOCHIMICA ACTA
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2019
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IF 4.258
Guojun Chen,Yanan Bai,Raymond Jianxiong Zeng,Liping Qin
Chromium isotopes are promising for monitoring and quantifying the extent of microbial Cr(VI) reduction. However, the mechanisms and factors that influence Cr isotope fractionation are not well understood. In the present study, we investigated the effects of different metabolic pathways and various environmental parameters on Cr isotope fractionation during Cr(VI) reduction by the extremely thermophilic bacterium Caldicellulosiruptor saccharolyticus . The Cr isotopic compositions were measured on unreacted Cr(VI) in the remaining solution. The reaction product is isotopically lighter than the reactant. The Cr isotope composition for remaining Cr(VI) in the solution followed a Rayleigh fractionation trend and thus became increasingly isotopically heavier as the reduction of Cr(VI) proceeded. Cr(VI) reduction mainly occurs on the cell surface by Ni–Fe hydrogenase; however, in the presence of CuCl 2 , the activity of Ni–Fe hydrogenase was inhibited, and Cr(VI) was reduced inside the cells. We found that despite different Cr(VI) reduction locations, Cr isotope enrichment factors ( ε = ( α − 1) × 1000, where α is the fractionation factor) were identical within uncertainty for experiments with and without CuCl 2 (−2.72 ± 0.67‰ and −2.92 ± 0.14‰, respectively). When added to the cell cultures, neutral red (NR) functioned as an electron carrier that enabled bacteria to drive the electron transfer processes. The ε values were also similar for experiments with and without NR (−2.53 ± 0.40‰ and −2.92 ± 0.14‰, respectively). We compared these ε values to investigate the effects of different electron transport pathways and cellular Cr(VI) transfer processes, including Cr(VI) transport across the cell envelope and binding to reacting enzymes, on Cr isotope fractionation. Furthermore, the effects of various environmental parameters on Cr isotope fractionation were tested, including temperature (50 °C and 70 °C), hydrogen concentration, and different electron donors (glucose and hydrogen). The ε values were similar at both tested temperatures and stayed within the previously observed range for mesophiles ; changes in hydrogen concentration also did not affect the ε values. However, the ε values were slightly higher with hydrogen as the electron donor (−3.64 ± 0.24‰) than those with glucose as the electron donor (−2.92 ± 0.14‰). In short, the Cr enrichment factors remained unchanged despite of changing microbial Cr (VI) reduction pathways and changing temperature conditions, but may be sensitive to the electron donor type.
研究领域:
微生物学
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地球化学
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DOI
高影响因子
WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY
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2017
·Vol. 33
·期 5
·1-8
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IF 1.658
Pan Lan-jia,Tang Xiao-da,Li Chun-xing,Yu Guang-wei,Wang Yin
Sulfamethazine (SM2) is an antimicrobial drug that is frequently detected in manure compost, is difficult to degrade at high temperatures and is potentially threatening to the environment. In this study, a thermophilic bacterium was isolated from the activated sludge of an antibiotics pharmaceutical factory; this bacterium has the ability to degrade SM2 at 70 °C, which is higher than the traditional manure composting temperature. The strain S-07 is closely related to Geobacillus thermoleovorans based on its 16S rRNA gene sequence. The optimal conditions for the degradation of SM2 are 70 °C, pH 6.0, 50 rpm rotation speed and 50 mL of culture volume. More than 95% of the SM2 contained in media was removed via co-metabolism within 24 h, which was a much higher percentage than that of the type strain of G. thermoleovorans . The supernatant from the S-07 culture grown in SM2-containing media showed slightly attenuated antibacterial activity. In addition, strain S-07 was able to degrade other sulfonamides, including sulfadiazine, sulfamethoxazole and sulfamerazine. These results imply that strain S-07 might be a new auxiliary bacterial resource for the biodegradation of sulfonamide residue in manure composting.
研究领域:
环境微生物学
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生物修复
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药学
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DOI
PubMed
高影响因子
ENVIRONMENTAL MICROBIOLOGY
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2021
·Vol. 24
·期 1
·436-450
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IF 5.491
Xiaoyu Qiu,Weiwei Wang,Lige Zhang,Lihua Guo,Ping Xu,Hongzhi Tang
Summary Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants threatening ecosystems and human health. Here, we isolated and characterized a new strain, Hydrogenibacillus sp. N12, which is a thermophilic PAH-degrader. Strain N12 utilizes naphthalene as a sole carbon and energy source above 60°C and co-metabolizes many other PAHs as well. The metabolites were identified in the catabolism of naphthalene by gas chromatography–mass spectrometry (GC–MS) and stable isotopic analysis. Based on the identified metabolites, we proposed two possible metabolic pathways, one via salicylic acid and the other via phthalic acid. Whole-genome sequencing reveals that strain N12 possesses a small chromosome of 2.6 Mb. Combining genetic and transcriptional information, we reveal a new gene cluster for the naphthalene degradation. The genes, designated as nar AaAb that are predicted to encode the alpha and beta subunits of naphthalene dioxygenase, were subsequently subcloned into Escherichia coli and the enzyme activity was detected by whole-cell transformation. Capacity to degrade several other tricyclic-PAHs was also characterized, suggesting co-existence of other constitutively expressed enzyme systems in strain N12 in addition to the naphthalene degradation gene cluster. Our study provides insights into the potential of the thermophilic PAH-degrader in biotechnology and environmental management applications.
研究领域:
环境微生物学
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生物修复
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基因组学
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DOI
PubMed
高影响因子
BIORESOURCE TECHNOLOGY
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2024
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IF 9.7
Ruju Zhang,Yingpeng Zhang,Yonglan Xi,Jin Zhou,Ting Han,Qiuqin Ma,Cong Wang,Fei Zhu,Xiaomei Ye
Initiating aerobic fermentation under low temperature is the main challenge for winter livestock manure composting. This study aims to address this issue by applying black soldier fly larvae (BSFL) frass as a co-composting additive to enhance the low-temperature composting process. Specifically, this work explored the effects of chicken manure and BSFL frass co-composting on the temperature, humus content, and microorganisms with fresh weight ratio of 2:1, 1:1, 1:2 (w/w) at 6 °C. The result showed frass could rapidly rise the temperature to 50 °C and significantly increased the humus content by 15.6 % ∼ 26.3 %. Moreover, microbial analysis revealed that Sphingobacteriaceae accelerated temperature rise via low-temperature reproduction, creating proper temperature for thermophilic bacteria ( Truepera and Georgia ). Additionally, Cellulomonas and other bacteria promoted organic matter degradation and participated in humus formation. This study presents a novel solution for low-temperature composting, providing practical insights for improving manure management in winter.
研究领域:
环境科学
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农业工程
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微生物学
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DOI
PubMed
高影响因子
ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY
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2018
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IF 2.776
Chen Zhou,Huiqing Wang,Youbin Si,Kang Wu,Amina Yousaf
The ability of anthraquinone-2,6-disulfonate (AQDS) and riboflavin to enhance the sulfamethoxazole (SMX) degradation coupled with the Fe(III) reduction by Shewanella oneidensis MR-1 was investigated. The results indicated that the SMX degradation rate was 38.5% with an initial SMX concentration at 0.04 mM. For the overall performance of AQDS and riboflavin mediated SMX degradation and iron reduction, the SMX degradation rate was gradually increased with the enhancement of iron reduction. Riboflavin had a stronger enhancement on SMX degradation and iron reduction than AQDS, but the enhancement was not positively correlated with electron shuttles concentration. A quantitative characterization of the electron transfer capacity (ETC) of the electron shuttles showed that the ETC was higher for riboflavin than AQDS. The S. oneidensis MR-1 16S rRNA gene copies results indicated that electron shuttles had a positive effect on the microbial activity of S. oneidensis MR-1. The LC MS result indicated that the products of the SMX biodegradation were 3-amino-5-methylisoxazole and 4-aminobenzenesulfonic acid, which suggested that the SMX biodegradation was caused by S N bond cleavage. This study indicates that the biochemical mechanisms play a vital role in SMX transformation and Fe(II) generation in this system.
研究领域:
环境微生物学
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生物修复
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环境化学
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产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2021
·
IF 13.273
Yuxuan Wu,Wenhui Wang,Junshuo Zhang,Min Sang,Yunqi Xu,Jianyu Zhou,Sheng Wang,Yibing Cai,Shouhu Xuan,Xinglong Gong
Thermophiles can survive in a high-temperature environment due to the synergy of hydrophobic interaction and electrostatic interaction in their proteins. Shear thickening fluid (STF) is a kind of concentrated suspension, which shows shear thickening (ST) behavior and can transform from a liquid state to a solid state under shearing. However, this special phenomenon relies on the hydrogen bonds between particles and dispersing medium. At elevated temperatures, the hydrogen bonds will break and the ST effect will become weaker or even disappear. Herein, inspired by the high-temperature resistance mechanism of thermophile proteins, a novel MOF-801 based STF with better ST effect at elevated temperatures is reported. Specifically, the hydrogen bonds that conventional STF relies on are replaced with hydrophobic interaction and electrostatic interaction, adopting a strategy of dispersing MOF-801 into a mixture containing poly(ethylene glycol), poly(acrylic acid), and Ca 2+ . When the temperature rises to 55 ℃, the storage modulus of M-STF rises from 13 Pa to 2036 Pa, and the suspension transforms to a solid-like state. Thus, a shapeable, self-healing, shear-stiffing, and conductive polymer-like substance can be obtained. In addition, a high-performance composite can be developed by impregnating M-STF into Kevlar, which shows promising applications in lightweight body protection.
研究领域:
材料科学
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生物工程
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化学工程
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机械工程
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产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
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2023
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IF 9.8
Yijie Chen,Zhen Zhen,Gaoyang Li,Huijun Li,Ting Wei,Fengcheng Huang,Tao Li,Changhong Yang,Lei Ren,Yanqiu Liang,Zhong Lin,Dayi Zhang
Di-2-ethylhexyl phthalate (DEHP) is a widespread persistent organic pollutant in the environment. As an ultimate barrier preventing pollutant entry into the ocean, mangrove plays an important role in coastal ecosystem. However, little information is known about DEHP degradation in mangrove rhizosphere. In this study, a rhizobox was used to separate four consecutive rhizosphere compartments with distance of 0–2, 2–4, 4–6, and > 6 mm to the rhizoplane of Kandelia obovata and investigate DEHP gradient degradation behavior in rhizosphere. Sediments closer to the rhizoplane exhibited higher DEHP degradation efficiencies (74.4 % in 0–2 mm layer). More precisely, mangrove rhizosphere promoted the benzoic acid pathway and non-selectively accelerated the production of mono(2-ethylhexyl) phthalate, phthalic acid and benzoic acid. Higher sediment organic matter content, lower pH and less humus in rhizosphere benefited DEHP hydrolysis. In addition, rhizosphere significantly increased microbial biomass and activities comparing to bulk sediments. Some bacterial lineages with potential DEHP degradation capability exhibited a distance-dependent pattern that decreased with the distance to the rhizoplane, including Bacillales , Acidothermaceae , Gammaproteobacteria , and Sphingobacteriales . Our findings suggested that mangrove rhizosphere could accelerate DEHP degradation by altering sediment physicochemical properties and microbial composition, showing positive effects on coastal ecosystem services for eliminating phthalate acid ester contamination.
研究领域:
环境科学
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微生物学
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生态学
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污染物降解
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DOI
PubMed
高影响因子
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