FOOD AND BIOPRODUCTS PROCESSING
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2023
·
IF 4.6
Yulu Du,Yue Wang,Tianyou Cui,Lianpeng Ge,Fan Yu,Mengqian Zhao,Qihang Xu,Mingjie Jin,Bo Chen,Xuwei Long
Biosurfactant surfactin has a high market value and broad application prospects in the food industry and various industrial fields. However, its production efficiency limits its suitability for real applications. In this study, a new Bacillus subtilis (sp.) 50499 strain was isolated from crude oil-contaminated soil and used to efficiently produce surfactin. The initial surfactin titer was 2.25 g/L after three days of fermentation. Adding 2 g/L of L -Leu significantly improved the titer to over 5.5 g/L after optimizing the culture medium at 37 °C. However, adding D -Leu had the opposite effect on surfactin production , and the surfactin titer dropped to below 0.2 g/L. Furthermore, the product of this strain was analyzed to confirm the identity of surfactin. The surfactin obtained in the present study reduced the surface tension of water to 28.6 mN/m at a critical micelle concentration of 20 mg/L. The emulsification index against n -hexane, corn , and crude oil was as high as over 90%. Hence, the present study provides a newly over-producing strain for surfactin production.
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Molecular Catalysis
·
2023
·
IF 4.6
Nan Jiang,Xiaotong Du,Liangyu Zheng
In this study, a series of chiral lactams were successfully prepared by one-pot two-step reactions. It included a transamination reaction catalyzed by a ω -transaminase from Bacillus megaterium ( ω -TA Bm ), and subsequent spontaneous cyclisation. The different amine donors were firstly screened with ethyl levulinate as an amine acceptor, and both the excellent conversion and enantiomeric excess ( e.e. p ) of >99% could be achieved with 4-bromophenylethylamine as an amine donor, however, the long reaction time of 24 h was unfavorable for its application. After the amino acid residue Thr120 situated in the small pocket was mutated to Ser, the T120S variant could exhibit 10.6-fold higher activity comparing to that of wild type, and achieve the reaction with both conversion and e.e. p of >99% within 3 h. The T120S variant could also be applied to prepare the other chiral γ- and δ-lactams with excellent conversion and e.e. p . Furthermore, the inclusion bodies of ω -TA Bm and its variants could be aggregated as “native-like structures” to continuously prepare the chiral lactam for 18 h. The aim of the study is to provide a simply and efficiently biocatalytic route for preparing chiral lactams.
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Metals
·
2023
·Vol. 13
·期 4
·649
·
IF 2.9
Xiaoxi Ruan,Linlin Yang,Yan Wang,Yizhe Dong,Dake Xu,Mingxing Zhang
The corrosion of carbon steel causes dramatic economic losses each year. Since conventional corrosion prevention approaches may cause pollution problems to the environment, ecofriendly and effective corrosion approaches are desired. Microbiologically influenced corrosion inhibition (MICI) has been reported as a sustainable corrosion prevention method. This work aims to evaluate the corrosion inhibition effect of two bacterial strains,Tenacibaculum mesophilumD-6 andBacillussp. Y-6 by choosing Q235 carbon steel as a model system. Scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and a series of electrochemical techniques were applied to study the corrosion prevention effect. The electrochemical and pitting results indicated thatT. mesophilumD-6 displayed a better corrosion protection effect.T. mesophilumD-6 formed a denser and thicker biofilm on the Q235 surface thanBacillussp. Y-6. The maximum thickness of theT. mesophilumD-6 biofilms was 11.6 ± 0.7 μm, which is about twice as thick than that ofBacillussp. Y-6. The corrosion prevention mechanism was ascribed to the formation of biofilms as a barrier to block corrosive agents such as O2. This study provides a theoretical foundation for the application of biofilms as green and effective corrosion inhibitors for carbon steel.Keywords:Q235 carbon steel;Tenacibaculum mesophilumD-6;Bacillussp. Y-6;corrosion inhibition;biofilm formation ability
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GREEN CHEMISTRY
·
2019
·Vol. 21
·期 9
·2286-2294
·
IF 9.405
Yuqing Qin,Fei Peng,Yonggang Hu
The oxidation of As(III) to As(V) is a critical process in the treatment of contaminated water. We found that 95% As(III) (10 mg L−1) could be rapidly oxidized to As(V) by a laccase–2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) system in 1 h. Based on this finding, we used Bacillus subtilis spores instead of laccase for As(III) oxidation with the same effect because the former had plenty of CotA–laccase on their surface. The catalytic ability of CotA protein and spores was confirmed by expressing the CotA protein and knocking out the cotA gene from wild-type spores. Both laccase– and spore–TEMPO systems displayed similar oxidation rate constants, Michaelis–Menten constants, and maximal velocities owing to the formation of the oxoammonium cation of TEMPO in the presence of dissolved oxygen. Several other laccase mediators such as 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic-acid) (ABTS), acetosyringone (AS), 1-hydroxybenzotriazole (HBT), 2-hydroxybutyl acrylate (HBA), violuric acid (VLA), 4-oxo-TEMPO, 4-amino-TEMPO, 4-methoxy-TEMPO, 4-hydroxy-TEMPO benzoate, and 4-hydroxy-TEMPO coupled with spores for As(III) oxidation were also investigated in detail. The spore–TEMPO system exhibited the highest oxidation efficiency and tolerated the addition of 10 mg L−1 Al3+, Ti4+, Cu2+, K+, Fe3+, Zn2+, Ni2+, Mg2+, Co2+, and Mn2+. Both laccase and spores recovered via ultrafiltration and centrifugation, respectively, could be reused for at least five cycles. The developed spore-based system has several advantages including eco-friendliness, ease of operation and storage, low cost, recyclability, sustainability, and without the need for enzyme purification. These findings may have promising implications for developing a new eco-friendly and cost-effective technology for the treatment of arsenic-containing water.
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AMB Express
·
2018
·Vol. 8
·期 1
·1-8
·
IF 1.719
Liang Xiao-Sheng,Liu Chun,Long Zhu,Guo Xiao-Hua
Spore counting in probiotic Bacillus cultures using dipicolinic acid (DPA) as a marker was studied for developing a rapid and simple detection method. The newly developed method is based on the fluorescence enhancement by a new chelating agent, which forms a complex with EuCl 3 and DPA. The results showed that 1,2-cyclohexanediamine-N,N,N′N′-tetraacetic acid (CyDTA) greatly enhanced the fluorescence intensity in all selected chelating agents. The optimal composition of the fluorescence complex DPA-Eu-CyDTA had a detection limit of 0.3 nM of DPA. Metal ions in high concentrations, including Cu 2+ , Fe 2+ , Fe 3+ , Al 3+ , and Zn 2+ , might lower the detection sensitivity, which could be eliminated by diluting the sample with the metal ions below 10 μM. The maximum release of DPA was achieved by heating treatments at 121 °C for at least 10 min for two types of Bacillus endospores. The spore concentrations and corresponding released DPA fluorescence intensities were linearly associated (coefficient R 2 = 0.9993 and 0.9995 for Bacillus subtilis MA139 and Bacillus licheniformis BL20386, respectively). The detection limit for both strains reached approximately 6800 spores/mL. The verification results showed that the DPA fluorimetry assay developed in the present study was fully consistent with the plate-counting assay. The study shows that the fluorescence complex DPA-Eu-CyDTA can be reliably used for the detection of endospores in Bacillus fermentation for the production of probiotics.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2018
·
IF 2.829
Leila Abdoli,Chunhai Guo,Xiuyong Chen,Xiaoyan He,Hua Li
Formation of microbial biofilm on marine structures is crucial for subsequent attachment of macro fouling species and understanding the impact of fluid conditions on formation and growth of the biofilm is essential for preventing biofouling. Here we report the effect of shear stresses generated by laminar and weakly turbulent flow on the adhesion of typical marine bacterium Bacillus sp. biofilm on stainless steel . Numerical simulation was carried out to calculate the distribution of pressure and shear stress applied on adhered bacteria. The shear stress was proportional to both the distance from the center of rotating disk and rotation speed. The stress reached 18 Pa as the flow velocity was 2.4 m/s and the rotation speed was 600 rpm. Further adhesion testing revealed that development of the bacterial biofilm in early stage was unaffected by the shear stresses. However, shear stress regulated the adherence orientations of the bacteria on the steel surface. Turbulent flow obviously shaped development of the architecture of the biofilm, as revealed by CLSM and SEM characterization. Biofilm growth patterns were clearly observed under weakly turbulent flow, however, they were not seen under laminar flow . The microcolonies assumed elongated forms, possibly triggered by exerted pressure drag force. The results give insights into possibly controlling the formation of marine biofilm on marine infrastructures for desired antifouling performances.
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ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
·
2018
·
IF 3.974
Yuan Chen,Yuancai Chen,Jingyi Wu,Jianyi Zhang
In this paper, we found a bacteria ( Bacillus wiedmannii MSM) that could not only culture quickly under aerobic condition , but also can biological reduction of Pd (II) under both aerobic and anaerobic conditions. For reducing Pd (II) by Bacillus wiedmannii MSM, the best electron donor was sodium formate and the best growth time was 24 h (mid-log growth phase cells). TEM indicated that a lot of palladium nanoparticles (Pd-NPs) were mainly located in the periplasmic space of the live cells. However, the autoclaved cells could not synthesize Pd-NPs, which proved the role of enzyme in the reduction of Pd (II). A few of Pd-NPs were only formed on the surface of Cu 2+ -treated cells, which proved the main but not the only role of periplasmic hydrogenase in the reduction of Pd (II). XRD and XPS also proved that Pd-NPs could be synthesized by live cells over broad ranges of temperature (20–40 °C) and pH (pH 3.0–7.0). This may be especially useful for in situ reduction and remediation of Pd (II) for both anaerobic and aerobic wastewater.
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ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
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2018
·
IF 3.974
Weijie Liu,Yanting You,Di Sun,Shiwei Wang,Jingrong Zhu,Cong Liu
Effluents loaded with various synthetic dyes are considered as a huge burden to the surrounding ecosystems. Sudan dyes are relatively difficult to decolorize due to its water-insolubility. In the present study, the strain Shewanella putrefaciens CN32 was firstly applied to decolorize Sudan dyes under the anaerobic condition , and the physicochemical parameters on the decolorization were optimized. The results demonstrated that the suitable decolorization condition was temperature 26 °C, initial pH 7.0–8.0 and NaCl concentrations 0–20 g/L. Electron competitive acceptors including nitrite, nitrate, dimethyl sulphoxide and oxygen could cause the significant inhibition to the decolorization of Sudan dyes. Biosurfactant rhamnolipid played a positive role in enhancing the decolorization of Sudan I. The co-culture of S. putrefaciens CN32 and Bacillus circulans BWL1061 is reported for the first time to accelerate the decolorization through improving the synergistic effect of enzymatic degradation and biological reductive effect. The highest decolorization of 90.23% to Sudan I was achieved within 108 h, suggesting that co-culture technique has a good potential in the treatment of dyeing wastewater. Furthermore, the microbial toxicity tests indicated that the toxicity of Sudan I to Escherichia coli BL21 and Bacillus subtilis 168 was obviously decreased after the decolorization.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2018
·
IF 3.909
Lu Zhao,Youzhi Zhou,Song Qin,Panpan Qin,Jianlin Chu,Bingfang He
β-Galactosidases can catalyze the hydrolysis of lactose and the synthesis of galacto-oligosaccharides (GOS) from lactose. The catalytic activity of β-galactosidases is usually inhibited by galactose and glucose, which hampers the complete hydrolysis of lactose in food products. In this report, a β-galactosidase (denoted as BMG) from Bacillus megaterium YZ08 without the inhibition by galactose and glucose is the first to our knowledge reported. Efficient secretory expression of BMG was successfully achieved in Bacillus subtilis WB800. With the increasing of galactose and glucose, the activity of BMG dramatically enhanced. With addition of 0.6 M galactose or 1 M glucose, the initial activity to o NPG hydrolysis was increased by 2.1-fold and 4.3-fold, respectively. Moreover, the synthetic rate of galacto-oligosaccharides was enhanced by 1.1-fold and 1.9-fold with the addition of 0.7 M galactose or glucose, respectively. The GOS (278 g/L) from 600 g/L lactose by BMG were efficiently produced within 12 h, and the substrate lactose was completely used up. These results suggest that BMG shows a potential application in the food industry.
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Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Zhenkun Deng,Bing Hu,Changliu He,Lihe Zhang,Xi Zhao,Xu Zhang
Understanding the biodegradation of benzotriazole compounds (BTs) is crucial for improving their removal from the environment. Experiments using activated sludge showed a 61.65 % removal rate for benzotriazole (BTA), primarily through biodegradation. Notably, microbial diversity changed significantly, especially within the class Bacilli , which increased from 0.17 % to 0.75 % over 21 days ( p < 0.05). A novel Bacillus strain, DH-12, was identified, capable of degrading over 85 % of BTA and 5-methylbenzotriazole (MBT) within 24 hours. During the degradation of three BTs, seven possible intermediates were detected. Strain DH-12 appears to use methylation and carboxylation pathways for transformation and shows aerobic dechlorination ability. Additionally, this strain helps reduce the toxicity of BTs. This research enhances our understanding of BTs biodegradation by both microbial communities and a specific bacterial strain, offering valuable insights for environmental biotransformation strategies.
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APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
·
2015
·Vol. 178
·期 3
·558-575
·
IF 1.735
Liang Jiayuan,Zhang Yun,Sun Aijun,Deng Dun,Hu Yunfeng
A novel microbial esterase BSE01281 identified from the Indian Ocean was cloned, expressed, and functionally characterized. Esterase BSE01281 could enanoselectively resolve (±)-1-phenylethanol and (±)-1-phenylethyl acetate through two types of enzymatic reactions. After the optimization of enzymatic reactions, BSE01281 could efficiently generate ( R )-1-phenylethyl acetate with high enantiomeric excess (>99 %) and high conversion (42 %) after 96 h trans-esterification reactions. Additionally, BSE01281 could also produce ( R )-1-phenylethanol ( e.e . > 99 %) and ( S )-1-phenylethyl acetate ( e.e . > 95 %) at a conversion of 49 % through direct hydrolysis of inexpensive racemic 1-phenylethyl acetate for 8 h. Optically pure ( R )-1-phenylethanol generated from direct enzymatic hydrolysis of racemic 1-phenylethyl acetate by BSE01281 is not easily prepared by dehydrogenases, which generally follow the “Prelog’s rule” and give ( S )-1-phenylethanol instead.
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BIOCONTROL SCIENCE AND TECHNOLOGY
·
2017
·
IF 0.919
Xiaohua Hu,Yajie Guo,Songqing Wu,Zhaoxia Liu,Tao Fu,Ensi Shao,Carballar-Lejarazú Rebeca,Guohui Zhao,Zhipeng Huang,Ivan Gelbič,Xiong Guan,Shuangquan Zou,Lei Xu,Lingling Zhang
Bacillus thuringiensis var. israelensis (Bti) is highly pathogenic to mosquito larvae and is widely used for mosquito control. Its mosquitocidal activity however is relatively low compared to many chemical insecticides. The detoxification mechanisms in the mosquito, among other things, might neutralize the Bti activity, resulting in resistance or tolerance. We tested whether or not the detoxification mechanisms against chemical insecticides might also operate against Bti, rendering it less effective. We targeted four enzymes in Aedes aegypti larvae involved in detoxification with inhibitors that have been used in resistance studies in chemical insecticides and assayed their effects on Bti toxicity. Results revealed that phenylmethanesulphonyl fluoride (PMSF), diethyl maleate, phenobarbital (PB), and piperonyl butoxide (PBO) altered Bti toxicity to various degrees. PMSF is a serine protease inhibitor that prevents Bti digestion and improves Bti activity. PB that induces several detoxifying enzymes had two different effects depending on the method of treatment. Mortality was higher when treatment with PB was discontinuous (149%) whereas with continuous treatment it was lower (101%). PBO, a typical cytochrome P450 inhibitor, increased Bti effect (159%). The combination of discontinuous pretreatment of larvae with PB followed by PBO had a synergistic effect and showed increased activity (146%). It appears that the mechanism for Bti resistance in mosquitoes is similar to that of chemical insecticides. Our studies indicate that we may be able to increase Bti activity by inhibiting some of the detoxification systems as active as broad spectrum chemical insecticides.
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