JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2022
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IF 5.895
Huibing Chi,Yilian Wang,Bingjie Xia,Yawen Zhou,Zhaoxin Lu,Fengxia Lu,Ping Zhu
l-Asparaginase has gained much attention for effectively treating acute lymphoblastic leukemia (ALL) and mitigating carcinogenic acrylamide in fried foods. Due to high-dose dependence for clinical treatment and low mitigation efficiency for thermal food processes caused by poor thermal stability, a method to achieve thermostable l-asparaginase has become a critical bottleneck. In this study, a rational design including free energy combined with structural and conservative analyses was applied to engineer the thermostability of l-asparaginase from Bacillus licheniformis (BlAsnase). Two enhanced thermostability mutants D172W and E207A were screened out by site-directed saturation mutagenesis. The double mutant D172W/E207A exhibited highly remarkable thermostability with a 65.8-fold longer half-life at 55 °C and 5 °C higher optimum reaction temperature and melting temperature (Tm) than those of wild-type BlAsnase. Further, secondary structure, sequence, molecular dynamics (MD), and 3D-structure analysis revealed that the excellent thermostability of the mutant D172W/E207A was on account of increased hydrophobicity and decreased flexibility, highly rigid structure, hydrophobic interactions, and favorable electrostatic potential. As the first report of rationally designing l-asparaginase with improved thermostability from B. licheniformis, this study offers a facile and efficient process to improve the thermostability of l-asparaginase for industrial applications.
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CHEMICAL ENGINEERING JOURNAL
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2023
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IF 15.1
Qiuting Yan,Yalin Yang,Wei Chen,Xiulan Weng,Gary Owens,Zuliang Chen
The efficient removal and recovery of rare earth elements (REEs) from mine wastewater is highly desirable due to the increasing public demands to both protect the environment and recover valuable REEs resources. In this study, bio-nanoparticles ( BC @FeNPs-EPS), which combined extracellular polymeric substances (EPS) and iron nanoparticles (FeNPs) were synthesized via Bacillus cereus and used to remove REEs such as Eu(III) from mine wastewaters. The removal efficiency of BC @FeNPs-EPS (90.2%) was consistently higher than the removal efficiencies of the three constituent components alone, FeNPs (85%), Free cell (67%) and EPS (10%) exhibited. SEM and XPS analysis indicated the existence of substantial organic capping agents derived from microorganisms on the FeNPs, where comparison of FTIR spectra before and after exposure to Eu(III) showed changes in both wavenumber and peak intensity of these various organic functional groups suggesting the formation of surface complexes with Eu(III), whereas Zeta potential measurements of the material also supported electrostatic interactions between Eu(III) and BC @FeNPs-EPS. Adsorption kinetics almost perfectly correlated with the non-linear pseudo-second-order model. Collectively, these results indicated that the removal mechanism for Eu(III) by BC @FeNPs-EPS involved both surface complexation and ion exchange and the additive effect removal of Eu(III) by FeNPs, Free cell and EPS. In addition, the practical removal efficiency of a range of REEs from real mine wastewaters by BC @FeNPs-EPS was consistently high being 88% for Eu(III), 89% for Tb(III) and 89% for Ce(III). The material produced was also highly reusable, maintaining a high Eu(III) removal rate (69%) even after 5 consecutive removal cycles.
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INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY
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2022
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IF 5.911
Haiying Cui,Jingyu Lu,Changzhu Li,Marwan M.A. Rashed,Lin Lin
Bacillus cereus ( B. cereus ) is a recognized foodborne pathogen widely distributed in various protein-rich foods , which is a huge challenge to food safety. Herein, a novel enzyme-responsive nanomaterial based on cationic starch (CSt) nanofibers loaded with carvacrol@casein nanoparticles (CL@CSNPs) was constructed (CL@CS/CSt nanofiber) to prevent the contamination of B. cereus in soybean products. Considering the excellent antibacterial activity of carvacrol (CL) against B. cereus , CL@CSNPs were prepared by electrostatic adsorption and hydrophobic interaction and characterized by SEM and FTIR .CL@CS/CSt nanofibers with better performance were determined by comparing the physical properties of the electrospinning solution and the prepared nanofiber. Nanofibers were prepared by electrospinning technology and analyzed by SEM and AFM to investigate the size and structural morphology of fibers. FTIR analyses were done to confirm the successful embedding of CL@CSNPs in CSt nanofibers. Subsequently, the controlled release of CL was verified by GC–MS and disc diffusion method. The application experiment results indicated that the treatment based on CL@CS/CSt nanofibers reduced the B. cereus in soy products by 2 log CFU/g, which reflected a significant antibacterial activity. In addition, CL@CS/CSt nanofibers could also prevent texture and chroma changes under refrigeration and maintain the sensory quality of soy products. Thus, CL@CS/CSt nanofibers appear to have great potential in controlling the contamination of soybean products by B. cereus while maintaining the physical quality.
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ENZYME AND MICROBIAL TECHNOLOGY
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2022
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IF 3.705
Kangli Wu,Meiling Shi,Xiaomei Pan,Jianqiang Zhang,Xiaomeng Zhang,Tong Shen,Yongqiang Tian
In this study, a ligninolytic enzyme-producing strain F5 was isolated and identified as Bacillus thuringiensis , which can efficiently degrade methylene blue (MB) dye. The optimal pH, temperature, rotation speed, NaCl concentration, and inoculum of strain F5 for MB degradation were pH 6.0, 30 °C, 140 rpm, 10 g/L NaCl, 4% inoculum (v/v), and the strain F5 had salt tolerance, the MB decolorization rate reached 95% after 12 h. The degraded products were characterized by UV–vis, FT-IR, and GC-MS. Based on products analysis, four different intermediates were identified, and a new pathway for the degradation of MB was proposed. The degradation of MB by strain F5 was due to the synergistic effects of laccase (Lac), manganese peroxidase (MnP), lignin peroxidase (LiP), and NADH-DCIP reductase ; among them, Lac and MnP were the key enzymes. The phytotoxicity results showed that MB degraded metabolites' toxicity was lower than that of the parent compound, indicating that the strain F5 had a detoxification effect on MB dyes.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2022
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IF 10.753
Zhen Han,Qihua Lin,Shusheng Zhang,Xinru Zhou,Si Li,Faqian Sun,Chaofeng Shen,Xiaomei Su
Polychlorinated biphenyl (PCB)-degrading strains resuscitated by resuscitation promoting factor (Rpf) enlarged pure degraders to screen effective bio-inoculants for soil bioaugmentation . In this study, whole-genome analysis and PCB-degrading performance of a resuscitated strain LS1 were investigated. Importantly, the persistence and the physiological response of soil-inoculated LS1 were checked. The results indicate that the Bacillus sp. strain LS1 possessed the potential to degrade polycyclic aromatic compounds. LS1 exhibited better performance in degrading PCBs 18 and 52, but lower PCB 77 degradation capability. At PCBs concentration of 10 mg/L, the degradation efficiencies of PCBs 18, 52 and 77 within 96 h were 62.8 %, 59.6 % and 39.8 %, respectively. Combined the bph genes and metabolites detected, as well as the genes found in the genome, the abilities of LS1 for oxidative dehalogenation and mineralization of PCBs via HOPDA-benzoate-protocatechuate- β -ketoadipate pathway were determined. Notably, LS1 can still maintain survival and culturable state after inoculation into PCB-contaminated soil for 70 days. This is the first report to demonstrate the fate of resuscitated strain when used as soil bio-inoculant, which revealed the necessity and feasibility of using resuscitated strains to enhance bioremediation of PCB-contaminated soils.
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INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
·
2022
·Vol. 23
·期 12
·6588
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IF 6.208
Jiafeng Niu,Ruxue Yan,Juan Shen,Xiaoyu Zhu,Fanqiang Meng,Zhaoxin Lu,Fengxia Lu
Type I L-asparaginase fromBacillus licheniformisZ-1 (BlAase) was efficiently produced and secreted inBacillus subtilisRIK 1285, but its low yield made it unsuitable for industrial use. Thus, a combined method was used in this study to boost BlAase synthesis inB. subtilis. First, fifteen single strong promoters were chosen to replace the original promoter P43, with PyvyD achieving the greatest BlAase activity (436.28 U/mL). Second, dual-promoter systems were built using four promoters (PyvyD, P43, PaprE, and PspoVG) with relatively high BlAase expression levels to boost BlAase output, with the engine of promoter PaprE-PyvyD reaching 502.11 U/mL. The activity of BlAase was also increased (568.59 U/mL) by modifying key portions of the PaprE-PyvyD promoter. Third, when the ribosome binding site (RBS) sequence of promoter PyvyD was replaced, BlAase activity reached 790.1 U/mL, which was 2.27 times greater than the original promoter P43 strain. After 36 h of cultivation, the BlAase expression level in a 10 L fermenter reached 2163.09 U/mL, which was 6.2 times greater than the initial strain using promoter P43. Moreover, the application potential of BlAase on acrylamide migration in potato chips was evaluated. Results showed that 89.50% of acrylamide in fried potato chips could be removed when combined with blanching and BlAase treatment. These findings revealed that combining transcription and translation techniques are effective strategies to boost recombinant protein output, and BlAase can be a great candidate for controlling acrylamide in food processing.Keywords:L-asparaginase;Bacillus subtilis;promoter;dual-promoter systems;ribosome binding site;scale-up fermentation;acrylamide
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ACS Sustainable Chemistry & Engineering
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2022
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IF 9.224
Ze-Wang Guo,Zi-Fu Ni,Min-Hua Zong,Wen-Yong Lou
Consolidated bioprocessing (CBP) has emerged as a promising strategy for green synthesis of 2,3-butanediol (BDO) from Jerusalem artichoke tubers (JAT). Here, modular metabolic engineering of Bacillus licheniformis MW3 was implemented, in which the overall BDO synthesis process was divided into four modules (inulin hydrolysis, sporulation elimination, carbon flux redistribution, and enantiopure meso-BDO synthesis). First, endo-inulinase was introduced to boost inulin utilization. Second, sporulation was blocked by spoIIE knockout, thus reducing the leakage risk of the genetically engineered strain from the fermentation plant. Third, more carbon flux was shunted into BDO production via exchanging the alsS start codon, blocking acetoin catabolism, and competing pathways. Finally, enantiopure meso-BDO was synthesized by gdh knockout. Encouragingly, the final engineered strain, MWO-8, produced meso-BDO with 99.3% purity at a titer, productivity, and yield of 82.51 g/L, 1.38 g/L/h, and 0.439 g/g, respectively. To our knowledge, this is the highest titer of BDO from JAT by CBP so far. Collectively, this work provides a highly promising alternative approach for sustainable and cost-effective production of BDO.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2021
·Vol. 29
·期 2
·1824-1835
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IF 4.223
Chen Yuan,Chen Yuancai
At present, there are many studies on microbial reduction of Pd (II), although few of these studies assess the bacterial toxicity of Pd (II) before and after reduction by microorganisms. In this study, the toxicity of Pd (II) to Bacillus wiedmannii MSM ( B. wiedmannii MSM) was assessed before and after reduction by live B. wiedmannii MSM cells (referred to as “Pd (0)-loaded cells”) and after biosorption by dead B. wiedmannii MSM cells (referred to as “Pd (II)-loaded cells”). B. wiedmannii MSM is a widely occurring, nonpathogenic aerobic bacterium. Compared with Pd (II), the EC 20 , EC 50 , and EC 80 of Pd (0)-loaded cells increased by 77.73-, 112.75-, and 163.91-fold, respectively, while the EC 20 , EC 50 , and EC 80 of Pd (II)-loaded cells increased by only 11.55-, 9.77-, and 8.29-fold, respectively. The sterilization contribution rates of the mechanisms of action of Pd (0)-loaded cells were ranked in the order of: remaining Pd (II) > oxidative stress > physical puncture. Pd (II) was found to increase cell membrane permeability, glutathione S-transferase (GST) enzyme activity, and reactive oxygen species levels in cells and decrease the cell membrane potential. XPS results indicated that Pd (II) increased the content of polysaccharides and peptides and decreased the content of hydrocarbons in cells. These findings reveal the bactericidal mechanism of toxicity of Pd (II) and Pd (0)-loaded cells on Bacillus wiedmannii MSM and provide an environmentally friendly and inexpensive method for Pd (II) detoxification.
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BIOCATALYSIS AND BIOTRANSFORMATION
·
2021
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IF 2.181
Lu Dong,Shujuan Qi,Jianwei Jia,Yun Zhang,Yunfeng Hu
Bacillus sp. DL-1 was isolated from the deep sea of the Western Pacific Ocean and behaved very good resistance to NaCl. The extracellular proteases of Bacillus sp. DL-1 were found to exhibit excellent enantioselectivity for the kinetic resolution of (±)-1-phenylethyl acetate. To improve the stability of the enzyme, the immobilized extracellular proteases were preparated by using 60 g kieselguhr and 1-L crude fermentation broth containing extracellular proteases of Bacillus sp. DL-1, shaking at 25 °C, 200 r/min for 10 h. Every gram of kieselguhr adsorbed 25.7 mg extracellular protease and the enzymatic activity recovery was 79.86%. The immobilized proteases preserved about 35.8% of its activity after 6 repeated uses, which were also used as biocatalyst to asymmetrically hydrolyse (±)-1-phenylethyl acetate for the preparation of (R)-1-phenylethanol and (S)-1-phenylethyl acetate with high optical purities. The effects of pH, temperature, enzyme concentration, substrate concentration, reaction time and additives (metal ions/surfactants) on the resolution were investigated by single factor experiments. Under the optimal reaction conditions (10 mM (±)-1-phenylethyl acetate, 40 mg/mL immobilized extracellular proteases, pH 7.5 (Tris-HCl), 5% (v/v) methanol and 45 °C for 2 h), (R)-1-phenylethanol was generated with the e.e.p being > 97%, and the yield being 53%, respectively. Analogously, under the optimal reaction conditions (10-mM (±)-1-phenylethyl acetate, 360 mg/mL immobilized extracellular proteases, pH 6.0 (PB), 5% (v/v) DMSO and 35 °C for 1.5 h), (S)-1-phenylethyl acetate was generated with the e.e.s being over 99% and the yield being 79%, respectively. Compared with the extracellular proteases from Bacillus sp. DL-2, the immobilized extracellular proteases from Bacillus sp. DL-1 exhibited higher hydrolytic activity and could asymmetrically hydrolyse (±)-1-phenylethyl acetate by using higher substrate concentrations, shorter reaction times to obtain higher yields. Notably, the extracellular proteases of Bacillus sp. DL-1 were demonstrated to behave the same enantio-preference as those of most other reported esterases/lipases. Proteases from deep-sea Bacillus sp. DL-1 are promising biocatalysts for the synthesis of valuable chiral chemicals.
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ACS Sustainable Chemistry & Engineering
·
2021
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IF 8.198
Kemin Lv,Zhimeng Yu,Marcelo M. Pedroso,Bin Wu,Zhen Gao,Bingfang He,Gerhard Schenk
Establishing a suitable immobilization strategy to improve the accessibility of immobilized cellulase for insoluble cellulose and subsequently recover the enzyme from the remaining substrate is crucial to promote the industrialization of biofuels. Here, using iminodiacetic acid (IDA) and Ni2+ ions, a novel metal-chelated copolymer of methacrylic acid and methyl methacrylate was prepared for the immobilization of His-tagged processive endoglucanase EG5C-1 via affinity interaction between polyhistidine tag and Ni2+. The optimum loading capacity of the functionalized polymer (Eud-IDA-Ni2+) for EG5C-1 was about 280 mg/g, where more than 80% of the activity was recovered. Immobilized EG5C-1 exhibited improved thermal and pH stability and better reusability than the free one, and after five cycles of usage, the hydrolysis productivity remained above 70% of the initial value. The Eud-IDA-Ni2+/EG5C-1 biocomposite displayed reversibly soluble–insoluble characteristics with pH change, which was in the soluble state during the enzyme reaction process but could be recovered in an insoluble form by lowering the pH after the reaction. Thus, the yield obtained from the hydrolysis of an insoluble phosphoric acid-swollen cellulose substrate was similar for the free and immobilized form of EG5C-1. Our combined results suggested that a metal-ion-chelated, pH-responsive polymer had the potential for His-tagged cellulase immobilization to improve both the operational efficiency and economic benefit of the cellulosic biorefinery industry.
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Microorganisms
·
2020
·Vol. 8
·期 11
·1750
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IF 4.152
Chun Li,Xiaoming Yuan,Na Li,Juan Wang,Shubo Yu,Haiyan Zeng,Jumei Zhang,Qingping Wu,Yu Ding
Bacillusphage φ29 and its relatives have been considered as one of the most important model organisms for DNA replication, transcription, morphogenesis, DNA packaging studies, and nanotechnology applications. Here, we isolated and characterized a new member of the φ29-like phage, namedBacillus cereusphage vB_BceP-DLc1. This phage, with a unique inserted gene cluster, has the largest genome among known φ29-like phages. DLc1 can use the surface carbohydrate structures of the host cell as receptors and only infects the most relatedB. cereusstrains, showing high host-specificity. The adsorption rate constant and life cycle of DLc1 under experimental conditions were also determined. Not only stable under temperatures below 55 °C and pH range from 5 to 11, the new phage also showed tolerance to high concentrations of NaCl, 75% ethanol, chloroform, and mechanical vortex, which is preferable for practical use in the food and pharmaceutical industries.Keywords:Bacillus cereus;bacteriophage;φ29;stability;adsorption;largest genome
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Marine Drugs
·
2020
·Vol. 18
·期 2
·126
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IF 4.073
Chunrui Ma,Xiao Li,Kun Yang,Shangyong Li
Chitooligosaccharide (COS) has been recognized to exhibit efficient anti-oxidant activity. Enzymatic hydrolysis using chitosanases can retain all the amino and hydroxyl groups of chitosan, which are necessary for its activity. In this study, a new chitosanase encoding gene,csnQ, was cloned from the marineBacillussp. Q1098 and expressed inEscherichia coli. The recombinant chitosanase, CsnQ, showed maximal activity at pH 5.31 and 60 °C. Determination of CsnQ pH-stability showed that CsnQ could retain more than 50% of its activity over a wide pH, from 3.60 to 9.80. CsnQ is an endo-type chitosanase, yielding chitodisaccharide as the main product. Additionally, in vitro and in vivo analyses indicated that chitodisaccharide possesses much more effective anti-oxidant activity than glucosamine and low molecular weight chitosan (LMW-CS) (~5 kDa). Notably, to our knowledge, this is the first evidence that chitodisaccharide is the minimal COS fragment required for free radical scavenging.Keywords:chitosanase;pH-stability;Bacillussp. Q1098;chitooligosaccharide;anti-oxidant activity
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