Pub Date : 2022-01-01DOI: 10.26789/aeb.2022.01.002
Mohammad A. Alkafaween, Mohammad Abu-Sini, Hamid A. Nagi Al-Jamal
Staphylococcus aureus is one of the most common pathogens in biofilm-associated chronic infections. S. aureus that live within biofilms avoid the host's immune response and are more resistant to antibiotics than planktonic bacteria. The current study was conducted to evaluate the antibacterial, antibiofilm and antivirulence of seven antibiotics (Ciprofloxacin (CP), Gentamicin (GEN), Tetracycline (TET), Amikacin (AMK), Clindamycin (CLI), Erythromycin (Ery) and Vancomycin (VAN) against S. aureus. The effects of seven antibiotics (CP, AMK, VAN, TET GEN, Ery and CLI) on S. aureus planktonic and biofilm were determined via Antibiotic susceptibility test, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), disruption of microcolony, biofilm inhibition and degradation (crystal violet staining) and RT-qPCR. Antibiotic susceptibility test showed that CP, AMK, VAN, TET GEN, Ery and CLI has antibacterial activity against S. aureus with an inhibition zone of 28 mm, 21 mm, 27 mm, 20 mm, 25 mm, 27 mm and 19 mm respectively. The results showed that CP and AMK possessed the lowest MIC value against S. aureus with 0.125 µg/mL and 0.25 µg/mL for VAN, TET and GEN and 1.0 for Ery and CLI. The recorded values for MBCs were 0.25 μg for CP and AMK for S. aureus, 0.5 μg for vancomycin, tetracycline and gentamicin for S. aureus and 1.0 μg for Ery and CLI for S. aureus. Notably, CP and AMK demonstrated considerable efficacy, as shown by the low values for MIC; 0.125 μg and MBC; 0.25 μg for S. aureus. All antibiotics were found to disrupt microcolony formation in S. aureus at MIC of each antibiotics. At 0.25 μg concentration to 8 μg concentration of each antibiotic were significantly found to degrade and inhibit biofilm formation of S. aureus. The RT-qPCR showed that four genes including argF, purC, adh, and fabG were downregulated, whilst, three genes including scdA, pykA and menB were upregulated after exposure to CP, AMK, VAN, TET GEN, Ery and CLI. This study showed the efficacy of seven antibiotics against planktonic, biofilm, gene expression and that different concentrations of antibiotics have different degrees of potential effect on established biofilm. In addition, a decreased expression of virulence genes in S. aureus will impact their pathogenicity. These results provide the theoretical parameters for the selection of effective antimicrobial in clinical therapy and demonstrate how to correctly use antibiotics at MIC and sub-MIC as preventive drugs.
{"title":"Antibiotic Susceptibility and Differential expression of virulence genes in Staphylococcus aureus","authors":"Mohammad A. Alkafaween, Mohammad Abu-Sini, Hamid A. Nagi Al-Jamal","doi":"10.26789/aeb.2022.01.002","DOIUrl":"https://doi.org/10.26789/aeb.2022.01.002","url":null,"abstract":"Staphylococcus aureus is one of the most common pathogens in biofilm-associated chronic infections. S. aureus that live within biofilms avoid the host's immune response and are more resistant to antibiotics than planktonic bacteria. The current study was conducted to evaluate the antibacterial, antibiofilm and antivirulence of seven antibiotics (Ciprofloxacin (CP), Gentamicin (GEN), Tetracycline (TET), Amikacin (AMK), Clindamycin (CLI), Erythromycin (Ery) and Vancomycin (VAN) against S. aureus. The effects of seven antibiotics (CP, AMK, VAN, TET GEN, Ery and CLI) on S. aureus planktonic and biofilm were determined via Antibiotic susceptibility test, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), disruption of microcolony, biofilm inhibition and degradation (crystal violet staining) and RT-qPCR. Antibiotic susceptibility test showed that CP, AMK, VAN, TET GEN, Ery and CLI has antibacterial activity against S. aureus with an inhibition zone of 28 mm, 21 mm, 27 mm, 20 mm, 25 mm, 27 mm and 19 mm respectively. The results showed that CP and AMK possessed the lowest MIC value against S. aureus with 0.125 µg/mL and 0.25 µg/mL for VAN, TET and GEN and 1.0 for Ery and CLI. The recorded values for MBCs were 0.25 μg for CP and AMK for S. aureus, 0.5 μg for vancomycin, tetracycline and gentamicin for S. aureus and 1.0 μg for Ery and CLI for S. aureus. Notably, CP and AMK demonstrated considerable efficacy, as shown by the low values for MIC; 0.125 μg and MBC; 0.25 μg for S. aureus. All antibiotics were found to disrupt microcolony formation in S. aureus at MIC of each antibiotics. At 0.25 μg concentration to 8 μg concentration of each antibiotic were significantly found to degrade and inhibit biofilm formation of S. aureus. The RT-qPCR showed that four genes including argF, purC, adh, and fabG were downregulated, whilst, three genes including scdA, pykA and menB were upregulated after exposure to CP, AMK, VAN, TET GEN, Ery and CLI. This study showed the efficacy of seven antibiotics against planktonic, biofilm, gene expression and that different concentrations of antibiotics have different degrees of potential effect on established biofilm. In addition, a decreased expression of virulence genes in S. aureus will impact their pathogenicity. These results provide the theoretical parameters for the selection of effective antimicrobial in clinical therapy and demonstrate how to correctly use antibiotics at MIC and sub-MIC as preventive drugs.","PeriodicalId":36987,"journal":{"name":"Applied Environmental Biotechnology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69126850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Surfactin is one of the most representative biosurfactants and exhibits excellent surface activity plus other biological effects. It has potential applications in microbial enhanced oil recovery, environmental bioremediation, agricultural bio-control, pharmacy, cosmetics and food industries. The low yield of the surfactant from wild strains is a key restriction for industrial applications. The construction of genetically engineered bacteria by promoter substitution is an effective method to enhance surfactin production, as the promoter is a key element in gene expression. This study focuses on constructing strains with efficient surfactin production by replacing the native srfA promoter by strong promoters. In this study, two different promoter patterns with different homology arm positions were used for srfA promoter substitution. The most efficient installation way was identified as the sequence between the transcriptions start site and ribosome binding site of srfA. Moreover, eight endogenous strong auto-inducible phase-dependent promoters were chosen to substitute the native promoter of srfA using an effective substitution by the CRISPR-Cas9 system. As a result, high surfactin yielding strains with potential application in industry were constructed. According to the results, three constructed strains with promoters P43, PspoVG, and PyvyD showed increased yields of 3.5, 2.8, and 2.3 times over the wild stain B. subtilis TD7.
{"title":"Improvement surfactin production by substitution of promoters in Bacillus subtilis TD7","authors":"Bozhong Mu, Fang Liu, Yi-Fan Liu, Yishu Qiao, Yu-Zhe Guo, Fang-Yue Kuang, Xiuying Lin, Jiang Ye, Jin-Feng Liu, Shi‐Zhong Yang, Huizhan Zhang, W. Sand","doi":"10.26789/aeb.2021.01.004","DOIUrl":"https://doi.org/10.26789/aeb.2021.01.004","url":null,"abstract":"Surfactin is one of the most representative biosurfactants and exhibits excellent surface activity plus other biological effects. It has potential applications in microbial enhanced oil recovery, environmental bioremediation, agricultural bio-control, pharmacy, cosmetics and food industries. The low yield of the surfactant from wild strains is a key restriction for industrial applications. The construction of genetically engineered bacteria by promoter substitution is an effective method to enhance surfactin production, as the promoter is a key element in gene expression. This study focuses on constructing strains with efficient surfactin production by replacing the native srfA promoter by strong promoters. In this study, two different promoter patterns with different homology arm positions were used for srfA promoter substitution. The most efficient installation way was identified as the sequence between the transcriptions start site and ribosome binding site of srfA. Moreover, eight endogenous strong auto-inducible phase-dependent promoters were chosen to substitute the native promoter of srfA using an effective substitution by the CRISPR-Cas9 system. As a result, high surfactin yielding strains with potential application in industry were constructed. According to the results, three constructed strains with promoters P43, PspoVG, and PyvyD showed increased yields of 3.5, 2.8, and 2.3 times over the wild stain B. subtilis TD7.","PeriodicalId":36987,"journal":{"name":"Applied Environmental Biotechnology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42251561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-17DOI: 10.26789/AEB.2021.01.003
J. Gu, Tsz Ching Mak
Phthalate esters (PAEs) are a group of endocrine-disrupting organic chemicals commonly used as additives in the manufacturing of a wide range of plastics. Large quantities of different phthalate esters have been used in specific products for quality and performance by the manufacturing industries, and they pose a significant risk to human health and the ecological quality of the environments due to leaching out of phthalates from plastic products and their high mobility. Since phthalate esters are most removed efficiently through biodegradation by microorganisms in the environments, it is important to understand the efficiency, microorganisms involved, biochemical transformation processes and mechanisms of phthalate metabolism by the specific microorganisms. This article addresses the degradation of endocrine-disrupting phthalates and their fates by an integrative comparison and analysis on efficient PAEs-degrading microorganisms, the microbial metabolism, and the biochemical processes and limitation. The comparison reveals that no significant difference is evident on efficiencies between single strains of bacteria or the mixed bacterial consortia when degradation can be carried out. However, there are a few important characteristics among the efficiencies of the PAEs-degrading bacteria. The microorganisms shall utilize the specific phthalate ester as the sole source of carbon and energy. They shall mineralize the substrates, including the original compound and its degradation intermediates to achieve a complete removal. In addition, it is of practical importance for the bacteria to adapt and survive in a range of temperatures, salinity and pH as well as in the presence of indigenous microorganisms in bioremediation of contaminated sites or wastewater treatment. This review also reveals that caution should be given to both the presentation and interpretation of the degradation results for a comprehensive knowledge, particularly data on bacterial growth, extraction and analysis of residual PAEs, and the confounding use of surfactants or co-substrate in the research. The public awareness of plasticizers as an environmental pollutant is mostly due to its increasing quantities being used, constant contacts with human population on a daily basis and potential health hazards. Its toxicity shall be address more focused on reproductive biology meaningfully than the traditional mortality test in toxicology for the significant effects on animals including human.
{"title":"Degradability and Biochemical Pathways of the Endocrine-disrupting Plasticizers Phthalate Esters in Plastics by Microorganisms","authors":"J. Gu, Tsz Ching Mak","doi":"10.26789/AEB.2021.01.003","DOIUrl":"https://doi.org/10.26789/AEB.2021.01.003","url":null,"abstract":"Phthalate esters (PAEs) are a group of endocrine-disrupting organic chemicals commonly used as additives in the manufacturing of a wide range of plastics. Large quantities of different phthalate esters have been used in specific products for quality and performance by the manufacturing industries, and they pose a significant risk to human health and the ecological quality of the environments due to leaching out of phthalates from plastic products and their high mobility. Since phthalate esters are most removed efficiently through biodegradation by microorganisms in the environments, it is important to understand the efficiency, microorganisms involved, biochemical transformation processes and mechanisms of phthalate metabolism by the specific microorganisms. This article addresses the degradation of endocrine-disrupting phthalates and their fates by an integrative comparison and analysis on efficient PAEs-degrading microorganisms, the microbial metabolism, and the biochemical processes and limitation. The comparison reveals that no significant difference is evident on efficiencies between single strains of bacteria or the mixed bacterial consortia when degradation can be carried out. However, there are a few important characteristics among the efficiencies of the PAEs-degrading bacteria. The microorganisms shall utilize the specific phthalate ester as the sole source of carbon and energy. They shall mineralize the substrates, including the original compound and its degradation intermediates to achieve a complete removal. In addition, it is of practical importance for the bacteria to adapt and survive in a range of temperatures, salinity and pH as well as in the presence of indigenous microorganisms in bioremediation of contaminated sites or wastewater treatment. This review also reveals that caution should be given to both the presentation and interpretation of the degradation results for a comprehensive knowledge, particularly data on bacterial growth, extraction and analysis of residual PAEs, and the confounding use of surfactants or co-substrate in the research. The public awareness of plasticizers as an environmental pollutant is mostly due to its increasing quantities being used, constant contacts with human population on a daily basis and potential health hazards. Its toxicity shall be address more focused on reproductive biology meaningfully than the traditional mortality test in toxicology for the significant effects on animals including human.","PeriodicalId":36987,"journal":{"name":"Applied Environmental Biotechnology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46446275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-11DOI: 10.26789/AEB.2021.01.002
M. Anand, R. Ravishankar, K. Vasist, Madhu H N
The demands for materials made of plastics are rapidly increasing, especially in food packaging application. Recently, attention has been drawn to the use of bio-reinforced composites in packaging, automotive, medical and construction applications due to increased concern for environmental sustainability. Poly(vinyl alcohol) (PVA) films reinforced with crystals (unbleached) prepared by solution casting method possessed significantly improved properties compared to film reinforced with cellulose (bleached). From the results, PVA films with the addition of 4% (w/w) of crystalline cellulose exhibited best combination of properties. In addition to good mechanical properties, this composite has good water resistance and biodegradability. The water absorption of biocomposite was found to be 22.63%. From X - ray diffraction (XRD) analysis, diffraction peaks of biocomposite was observed at 2θ = 22.4384. From scanning electron microscopy (SEM) analysis it was found that fractures at surfaces of biocomposite film were smooth and even without any porosity and uniform dispersion of jute crystals in the matrix.
{"title":"Characterization of Lignocellulosic Fibers Reinforced with Poly(vinyl alcohol)","authors":"M. Anand, R. Ravishankar, K. Vasist, Madhu H N","doi":"10.26789/AEB.2021.01.002","DOIUrl":"https://doi.org/10.26789/AEB.2021.01.002","url":null,"abstract":"The demands for materials made of plastics are rapidly increasing, especially in food packaging application. Recently, attention has been drawn to the use of bio-reinforced composites in packaging, automotive, medical and construction applications due to increased concern for environmental sustainability. Poly(vinyl alcohol) (PVA) films reinforced with crystals (unbleached) prepared by solution casting method possessed significantly improved properties compared to film reinforced with cellulose (bleached). From the results, PVA films with the addition of 4% (w/w) of crystalline cellulose exhibited best combination of properties. In addition to good mechanical properties, this composite has good water resistance and biodegradability. The water absorption of biocomposite was found to be 22.63%. From X - ray diffraction (XRD) analysis, diffraction peaks of biocomposite was observed at 2θ = 22.4384. From scanning electron microscopy (SEM) analysis it was found that fractures at surfaces of biocomposite film were smooth and even without any porosity and uniform dispersion of jute crystals in the matrix.","PeriodicalId":36987,"journal":{"name":"Applied Environmental Biotechnology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69126721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.26789/aeb.2021.02.005
Himanshi Mangla, Hitesh Sharma, S. Dave, Jebi Sudan, H. Pathak
Petroleum hydrocarbon compounds are recognized to be neurotoxic and xenobiotic organic pollutants, because they are presently a large environmental issue as a result of the increased mining of petroleum compounds and similar products, both of which have important environmental consequences. Petroleum products include cancer - causing compounds which can have a range of impacts on ecology biotic and abiotic variables, and leakage is generally induced by mistakes in pumping, transportation, and refining. Physical and biological procedures are commonly cleaned to separate petroleum from polluted areas. Both methods are efficient but can be costly. Because it is not very costly and leads to complete mineralization, bioremediation is the best and most advanced method for treating these polluted sites. Another very significant and successful natural technique for eliminating petroleum hydrocarbon environmental contaminants is microbial decomposition. Hydrocarbon contaminants could be deteriorated by a variety of indigenous microbes in water and soil. A variety of limiting variables have been identified that impact petroleum hydrocarbon biodegradation. This study outlines the aerobic and anaerobic microbiological breakdown of organic compounds, as well as the different variables that influence the process. Microbial deterioration could be regarded a vital aspect in the cleaning approach for petroleum hydrocarbon recovery, it can be inferred.
{"title":"Microbial mechanism of petroleum hydrocarbons degradation: “An Environmental perspective”","authors":"Himanshi Mangla, Hitesh Sharma, S. Dave, Jebi Sudan, H. Pathak","doi":"10.26789/aeb.2021.02.005","DOIUrl":"https://doi.org/10.26789/aeb.2021.02.005","url":null,"abstract":"Petroleum hydrocarbon compounds are recognized to be neurotoxic and xenobiotic organic pollutants, because they are presently a large environmental issue as a result of the increased mining of petroleum compounds and similar products, both of which have important environmental consequences. Petroleum products include cancer - causing compounds which can have a range of impacts on ecology biotic and abiotic variables, and leakage is generally induced by mistakes in pumping, transportation, and refining. Physical and biological procedures are commonly cleaned to separate petroleum from polluted areas. Both methods are efficient but can be costly. Because it is not very costly and leads to complete mineralization, bioremediation is the best and most advanced method for treating these polluted sites. Another very significant and successful natural technique for eliminating petroleum hydrocarbon environmental contaminants is microbial decomposition. Hydrocarbon contaminants could be deteriorated by a variety of indigenous microbes in water and soil. A variety of limiting variables have been identified that impact petroleum hydrocarbon biodegradation. This study outlines the aerobic and anaerobic microbiological breakdown of organic compounds, as well as the different variables that influence the process. Microbial deterioration could be regarded a vital aspect in the cleaning approach for petroleum hydrocarbon recovery, it can be inferred.","PeriodicalId":36987,"journal":{"name":"Applied Environmental Biotechnology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69126835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dissolved organic matter (DOM) and Cu(II), originated from livestock manure, often co-exist in livestock effluents. The effects of DOM on adsorption of Cu(II) by adsorbent remain unknown, which may prevent the removal of Cu(II) from livestock effluents using the method of adsorption. In this study, the effects of DOM on adsorption behaviors of Cu(II) by Aliinostoc sp. YYLX235, a epiphytic cyanobacterium, were investigated. The results showed that Aliinostoc could effectively bind with Cu(II) and remove it from water. Rather than absorption, most of Cu(II) were bound on the cell surface through adsorption. The decay of Aliinostoc did not resulted in rapid release of Cu(II) into water. The amount of Cu(II) adsorbed by Aliinostoc through ion exchange and complexation was decreased by DOM addition.
{"title":"Cattle manure DOM on adsorption of copper by the cyanobacterium Aliinostoc species","authors":"Qiong Yan, Chen-Xi Sun, Ye-cheng Feng, Kanying Miao, Siqing Wang, J. Shao","doi":"10.26789/aeb.2021.02.002","DOIUrl":"https://doi.org/10.26789/aeb.2021.02.002","url":null,"abstract":"Dissolved organic matter (DOM) and Cu(II), originated from livestock manure, often co-exist in livestock effluents. The effects of DOM on adsorption of Cu(II) by adsorbent remain unknown, which may prevent the removal of Cu(II) from livestock effluents using the method of adsorption. In this study, the effects of DOM on adsorption behaviors of Cu(II) by Aliinostoc sp. YYLX235, a epiphytic cyanobacterium, were investigated. The results showed that Aliinostoc could effectively bind with Cu(II) and remove it from water. Rather than absorption, most of Cu(II) were bound on the cell surface through adsorption. The decay of Aliinostoc did not resulted in rapid release of Cu(II) into water. The amount of Cu(II) adsorbed by Aliinostoc through ion exchange and complexation was decreased by DOM addition.","PeriodicalId":36987,"journal":{"name":"Applied Environmental Biotechnology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69126756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.26789/aeb.2021.02.004
Zhong-Huo Li, Fangfang Min, Haoming Chen
Biochar is one of the most concerned research hotspots at present, which is a stable and carbon-rich solid produced by pyrolysis of organic biomass under anoxic conditions. Biochar has abundant pore structure, functional groups, aromatic hydrocarbons and other characteristics, which enable it to improve soil physical and chemical properties, increase nutrient content, and regulate soil microbial community structure. In recent years, with the continuous research on biochar, the role of biochar in the remediation of heavy metal pollution has been further studied. The physical adsorption, ion exchange, electrostatic attraction, complexation reaction, mineral precipitation, redox and other functions of biochar are the main factors for repairing heavy metal ions. In addition, immobilization is the primary goal of biochar remediation of heavy metals in agricultural soils, because it can greatly reduce the risk of human health caused by heavy metals entering the food chain. This paper reviewed the current knowledge of biochar and its function in agricultural heavy metal soil. Based on the background of heavy metal pollution in agricultural soil in China, the possible remediation mechanism of biochar was discussed. It provides scientific basis for the development and application of biochar in the remediation of heavy metal pollution in agricultural soil in China.
{"title":"Biochar as a potential soil remediation agent for heavy metals in agriculture","authors":"Zhong-Huo Li, Fangfang Min, Haoming Chen","doi":"10.26789/aeb.2021.02.004","DOIUrl":"https://doi.org/10.26789/aeb.2021.02.004","url":null,"abstract":"Biochar is one of the most concerned research hotspots at present, which is a stable and carbon-rich solid produced by pyrolysis of organic biomass under anoxic conditions. Biochar has abundant pore structure, functional groups, aromatic hydrocarbons and other characteristics, which enable it to improve soil physical and chemical properties, increase nutrient content, and regulate soil microbial community structure. In recent years, with the continuous research on biochar, the role of biochar in the remediation of heavy metal pollution has been further studied. The physical adsorption, ion exchange, electrostatic attraction, complexation reaction, mineral precipitation, redox and other functions of biochar are the main factors for repairing heavy metal ions. In addition, immobilization is the primary goal of biochar remediation of heavy metals in agricultural soils, because it can greatly reduce the risk of human health caused by heavy metals entering the food chain. This paper reviewed the current knowledge of biochar and its function in agricultural heavy metal soil. Based on the background of heavy metal pollution in agricultural soil in China, the possible remediation mechanism of biochar was discussed. It provides scientific basis for the development and application of biochar in the remediation of heavy metal pollution in agricultural soil in China.","PeriodicalId":36987,"journal":{"name":"Applied Environmental Biotechnology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69126821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.26789/aeb.2021.01.005
{"title":"Different optimization conditions required to enhance the reduction potential of silver nanoparticle biosynthesis via the Mycelia-free filtrate step using the fungus Aspergillus flavus","authors":"","doi":"10.26789/aeb.2021.01.005","DOIUrl":"https://doi.org/10.26789/aeb.2021.01.005","url":null,"abstract":"","PeriodicalId":36987,"journal":{"name":"Applied Environmental Biotechnology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69126730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.26789/aeb.2021.02.003
Mohammad A. Alkafaween, Abu Bakar Mohd Hilmi
Biofilm formation has different stages and can be classified based on the bacterial strain, culture vessel, and the method employed. Biofilm formation is carried out in culture vessels to represent mode of infection in humans. Microbial concentration, growth medium, supplement, and incubation time are key factors to successfully form biofilm in a culture vessel. This study aimed to identify the optimum conditions for biofilm formation in a 96-well plate by culturing Pseudomonas aeruginosa and Streptococcus pyogenes. We utilized the infectious and pathogenic bacteria, P. aeruginosa and S. pyogenes strains. These bacteria were cultured in Mueller–Hinton Broth (MHB) and Tryptic Soy Broth (TSB) at two different optical densities OD600 (0.05) and OD600 (0.1). After a certain incubation time, the formed biofilm was stained by using 0.1% crystal violet. The stained bacteria were disaggregated and measured using a microplate reader. Biofilm was then classified based on bacterial adherence to the plate. Our results showed that P. aeruginosa and S. pyogenes biofilms were strongly formed on days 3 and 5 in MHB and TSB, respectively. However, the strongest biofilm formation was seen on day 3 after P. aeruginosa being incubated in MHB at OD600 (0.1) and after S. pyogenes being incubated in MHB at OD600 (0.05). Biofilm formation is ranged between weak, moderate, and strong in accordance with the density of bacterial adhesion. P. aeruginosa and S. pyogenes biofilms were optimized at specific OD600 (0.1 and 0.05, respectively) for 3 days’ cultivation in MHB.
{"title":"Evaluation of the effect of different growth media and incubation time on the suitability of biofilm formation by Pseudomonas aeruginosa and Streptococcus pyogenes","authors":"Mohammad A. Alkafaween, Abu Bakar Mohd Hilmi","doi":"10.26789/aeb.2021.02.003","DOIUrl":"https://doi.org/10.26789/aeb.2021.02.003","url":null,"abstract":"Biofilm formation has different stages and can be classified based on the bacterial strain, culture vessel, and the method employed. Biofilm formation is carried out in culture vessels to represent mode of infection in humans. Microbial concentration, growth medium, supplement, and incubation time are key factors to successfully form biofilm in a culture vessel. This study aimed to identify the optimum conditions for biofilm formation in a 96-well plate by culturing Pseudomonas aeruginosa and Streptococcus pyogenes. We utilized the infectious and pathogenic bacteria, P. aeruginosa and S. pyogenes strains. These bacteria were cultured in Mueller–Hinton Broth (MHB) and Tryptic Soy Broth (TSB) at two different optical densities OD600 (0.05) and OD600 (0.1). After a certain incubation time, the formed biofilm was stained by using 0.1% crystal violet. The stained bacteria were disaggregated and measured using a microplate reader. Biofilm was then classified based on bacterial adherence to the plate. Our results showed that P. aeruginosa and S. pyogenes biofilms were strongly formed on days 3 and 5 in MHB and TSB, respectively. However, the strongest biofilm formation was seen on day 3 after P. aeruginosa being incubated in MHB at OD600 (0.1) and after S. pyogenes being incubated in MHB at OD600 (0.05). Biofilm formation is ranged between weak, moderate, and strong in accordance with the density of bacterial adhesion. P. aeruginosa and S. pyogenes biofilms were optimized at specific OD600 (0.1 and 0.05, respectively) for 3 days’ cultivation in MHB.","PeriodicalId":36987,"journal":{"name":"Applied Environmental Biotechnology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69126777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.26789/aeb.2021.02.001
Mousa K. Magharbeh, Khaled M Khleifat, Mohammad A. Al-kafaween, Razan Saraireh, Moath Alqaraleh, H. Qaralleh, Amjad Al-Tarawneh, Muhamad O. Al-limoun, T. El-Hasan, T. Hujran, Salah H. Ajbour, N. Jarrah, Malik Amonov, Hamid Ali Nagi Al-Jamal
Phenol is one of the main pollutants that have a serious impact on the environment and can even be very critical to human health. The biodegradation of phenol can be considered an increasingly important pollution control process. In this study, the degradation of phenol by Bacillus simplex was investigated for the first time under different growth conditions. Six different initial concentrations of phenol were used as the primary substrate. Culture conditions had an important effect on these cells' ability to biodegrade phenol. The best growth of this organism and its highest biodegradation level of phenol were noticed at pH 7, temperature 28 °C, and periods of 36 and 96 h, respectively. The GC-MS analysis of the bacterial culture sample revealed that further degradation of the catechol by 1,2-dioxygenase produce a cis, cis-mucconic acid via ortho-pathway and/or by 2,3-dioxygenase into 2-hydroxymucconic semialdehyde via meta-pathway. The highest biodegradation rate was perceived at 700 mg/L initial phenol concentration. Approximately 90% of the phenol (700 mg / L) was removed in less than 96 hours of incubation time. It was found that the Haldane model best fitted the relationship between the specific growth rate and the initial phenol concentration, whereas the phenol biodegradation profiles with time could be adequately described by the modified Gompertz model. The obtained parameters from the Haldane equation are: 1.05 h−1, 9.14 ppm, and 329 ppm for Haldane's maximum specific growth rate, the half-saturation coefficient, and the Haldane’s growth kinetics inhibition coefficient, respectively. The Haldane equation fitted the experimental data by minimizing the sum of squared error (SSR) to 1.36 X 10-3.
苯酚是对环境有严重影响的主要污染物之一，甚至可能对人体健康非常关键。苯酚的生物降解可以被认为是一个日益重要的污染控制过程。本研究首次研究了单纯芽孢杆菌在不同生长条件下对苯酚的降解。六种不同初始浓度的苯酚作为主要底物。培养条件对这些细胞生物降解苯酚的能力有重要影响。在pH为7、温度为28℃、时间为36 h和96 h时，该菌的生长最佳，对苯酚的生物降解水平最高。细菌培养样品的GC-MS分析表明，1,2-双加氧酶通过正途径进一步降解儿茶酚生成顺式，顺式mucconic酸，或2,3-双加氧酶通过后途径进一步降解生成2-羟基mucconic半醛。苯酚初始浓度为700 mg/L时生物降解率最高。在不到96小时的孵育时间内，约90%的苯酚(700毫克/升)被去除。结果表明，Haldane模型能较好地拟合特定生长速率与苯酚初始浓度之间的关系，而改进的Gompertz模型能较好地描述苯酚随时间的生物降解曲线。由霍尔丹方程得到的霍尔丹最大比生长速率、半饱和系数和生长动力学抑制系数分别为1.05 h−1、9.14 ppm和329 ppm。Haldane方程通过最小化均方根误差(SSR)为1.36 X 10-3来拟合实验数据。
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