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Sachdeva S, Sarethy IP. Diving into freshwater microbial metabolites: Pioneering research and future prospects. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2024:1-19. [PMID: 38887995 DOI: 10.1080/09603123.2024.2351153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 04/30/2024] [Indexed: 06/20/2024]
Abstract
In practically every facet of life, especially nutrition, agriculture, and healthcare, microorganisms offer a prospective origin for abundant natural substances and products. Among these microorganisms, bacteria also possess the capability to rapidly acclimate to diverse environments, utilize varied resources, and effectively respond to environmental fluctuations, including those influenced by human activities like pollution and climate change. The ever-changing environment of freshwater bodies influences bacterial communities, offering opportunities for improving health and environmental conservation that remain unexplored. Herein, the study discusses the bacterial taxa along with specialised metabolites with antioxidant, antibacterial, and anticancer activity that have been identified from freshwater environments, thus achieving Sustainable Development Goals addressing health and wellbeing (SDG-3), economic growth (SDG-8) along with industrial development (SDG-9). The present review is intended as a compendium for research teams working in the fields of medicinal chemistry, organic chemistry, clinical research, and natural product chemistry.
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Affiliation(s)
- Saloni Sachdeva
- Department of Biotechnology, Jaypee Institute of Information Technology, Noida, India
| | - Indira P Sarethy
- Department of Biotechnology, Jaypee Institute of Information Technology, Noida, India
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Rafiee Z, Jalili Tabaii M, Moradi M, Harirchi S. Unveiling Antibacterial Potential and Physiological Characteristics of Thermophilic Bacteria Isolated from a Hot Spring in Iran. Microorganisms 2024; 12:834. [PMID: 38674778 PMCID: PMC11051818 DOI: 10.3390/microorganisms12040834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/06/2024] [Accepted: 04/15/2024] [Indexed: 04/28/2024] Open
Abstract
The increasing worldwide demand for antimicrobial agents has significantly contributed to the alarming rise of antimicrobial resistance, posing a grave threat to human life. Consequently, there is a pressing need to explore uncharted environments, seeking out novel antimicrobial compounds that display exceptionally efficient capabilities. Hot springs harbor microorganisms possessing remarkable properties, rendering them an invaluable resource for uncovering groundbreaking antimicrobial compounds. In this study, thermophilic bacteria were isolated from Mahallat Hot Spring, Iran. Out of the 30 isolates examined, 3 strains exhibited the most significant antibacterial activities against Escherichia coli and Staphylococcus aureus. Furthermore, the supernatants of the isolated strains exhibited remarkable antibacterial activity, displaying notable resistance to temperatures as high as 75 °C for 30 min. It was determined that the two strains showed high similarity to the Bacillus genus, while strain Kh3 was classified as Saccharomonospora azurea. All three strains exhibited tolerance to NaCl. Bacillus strains demonstrated optimal growth at pH 5 and 40 °C, whereas S. azurea exhibited optimal growth at pH 9 and 45 °C. Accordingly, hot springs present promising natural reservoirs for the isolation of resilient strains possessing antibacterial properties, which can be utilized in disease treatment or within the food industry.
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Affiliation(s)
- Zeinab Rafiee
- Department of Biotechnology, Faculty of Biological Sciences and Technology, Shahid Ashrafi Esfahani University, Isfahan 81799-49999, Iran; (Z.R.); (M.M.)
| | - Maryam Jalili Tabaii
- Department of Biotechnology, Faculty of Biological Sciences and Technology, Shahid Ashrafi Esfahani University, Isfahan 81799-49999, Iran; (Z.R.); (M.M.)
| | - Maryam Moradi
- Department of Biotechnology, Faculty of Biological Sciences and Technology, Shahid Ashrafi Esfahani University, Isfahan 81799-49999, Iran; (Z.R.); (M.M.)
| | - Sharareh Harirchi
- Swedish Centre for Resource Recovery, University of Borås, 501 90 Borås, Sweden
- Department of Biotechnology, Iranian Research Organization for Science and Technology, Tehran P.O. Box 3353-5111, Iran
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Wang Y, Haqmal MA, Liang YD, Muhammad I, Zhao XO, Elken EM, Gao YH, Jia Y, He CG, Wang YM, Kong LC, Ma HX. Antibacterial activity and cytotoxicity of a novel bacteriocin isolated from Pseudomonas sp. strain 166. Microb Biotechnol 2022; 15:2337-2350. [PMID: 35849816 PMCID: PMC9437881 DOI: 10.1111/1751-7915.14096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 05/15/2022] [Accepted: 05/18/2022] [Indexed: 11/30/2022] Open
Abstract
Pseudomonas sp. strain 166 was isolated from soil samples from Changbai Mountains. A novel bacteriocin PA166 from Pseudomonas sp. 166 was purified using ammonium sulfate, dextran gel chromatography column and Q-Sepharose column chromatography successively. The molecular mass of bacteriocin PA166 was found to be 49.38 kDa by SDS-PAGE and liquid chromatography-mass spectrometry (MS)/MS. Bacteriocin PA166 showed stability at a wide range of pH (2-10), and thermal stability (40, 60, 80 and 100°C). The bacteriocin PA166 antimicrobial activity was slightly inhibited by Ca2+ , K+ and Mg2+ . The minimum bactericidal concentrations of bacteriocin PA166 against five Pasteurella multocida strains ranged from 2 to 8 μg ml-1 . Bacteriocin PA166 showed low cytotoxicity and a higher treatment index (TI = 82.51). Fluorescence spectroscopy indicated that bacteriocin PA166 destroyed the cell membrane to exert antimicrobial activity. In summary, bacteriocin PA166 had strong antibacterial activity, high TI and low toxicity, and hence could serve as a potential clinical therapeutic drug.
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Affiliation(s)
- Yu Wang
- College of Veterinary Medicine, Jilin Agricultural University, 130118, Changchun, Jilin, China
| | - M Aman Haqmal
- College of Veterinary Medicine, Jilin Agricultural University, 130118, Changchun, Jilin, China
| | - Yue-Dong Liang
- College of Veterinary Medicine, Jilin Agricultural University, 130118, Changchun, Jilin, China
| | - Inam Muhammad
- College of Veterinary Medicine, Jilin Agricultural University, 130118, Changchun, Jilin, China.,Department of Animal Sciences, Shaheed Benazir Bhutto University Sheringal Dir Upper-Pakistan, Sheringal, Pakistan
| | - Xiao-Ou Zhao
- College of Veterinary Medicine, Jilin Agricultural University, 130118, Changchun, Jilin, China
| | - Emad Mohammed Elken
- College of Veterinary Medicine, Jilin Agricultural University, 130118, Changchun, Jilin, China.,Animal Production Department, Faculty of Agriculture, Al-Azhar University, Nasr City, Cairo, 11884, Egypt
| | - Yun-Hang Gao
- College of Veterinary Medicine, Jilin Agricultural University, 130118, Changchun, Jilin, China
| | - Yu Jia
- Jilin Agricultural University, College of Life Science, Changchun, China
| | - Cheng-Guang He
- Jilin Agricultural University, College of Life Science, Changchun, China
| | - Yi-Ming Wang
- College of Veterinary Medicine, Jilin Agricultural University, 130118, Changchun, Jilin, China
| | - Ling-Cong Kong
- College of Veterinary Medicine, Jilin Agricultural University, 130118, Changchun, Jilin, China.,The Key Laboratory of New Veterinary Drug Research and Development of Jilin Province, Jilin Agricultural University, Xincheng Street No. 2888, Changchun, 130118, China
| | - Hong-Xia Ma
- Jilin Agricultural University, College of Life Science, Changchun, China.,The Key Laboratory of New Veterinary Drug Research and Development of Jilin Province, Jilin Agricultural University, Xincheng Street No. 2888, Changchun, 130118, China.,The Engineering Research Center of Bioreactor and Drug Development, Ministry of Education, Jilin Agricultural University, Changchun, China
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Zada S, Xie J, Yang M, Yang X, Sajjad W, Rafiq M, Hasan F, Hu Z, Wang H. Composition and functional profiles of microbial communities in two geochemically and mineralogically different caves. Appl Microbiol Biotechnol 2021; 105:8921-8936. [PMID: 34738169 DOI: 10.1007/s00253-021-11658-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 10/17/2021] [Accepted: 10/22/2021] [Indexed: 12/18/2022]
Abstract
Microbial communities in cave ecosystems have specific survival strategies, which is far from being well explicated. Here, we reported the genetic and functional diversity of bacteria and archaea in typical limestone (Kashmir Cave) and silicate-containing (Tiser Cave) caves. X-ray diffraction (XRD) and Fourier transform infrared spectroscopic (FTIR) analyses revealed the different geochemical and mineral compositions of the two caves. Amplicon barcode sequencing revealed the dominancy of Actinobacteria and Proteobacteria in Kashmir and Tiser Caves. Bacteroidetes and Firmicutes were the dominant phyla in Tiser Cave, and the abundance is relatively small in Kashmir Cave. Archaea was also abundant prokaryotes in Kashmir Cave, but it only accounted for 0.723% of the total prokaryote sequences in Tiser Cave. Functional analysis based on metagenomic sequencing data revealed that a large number of functional potential genes involved in nutrient metabolism and biosynthesis of bioactive compounds in Tiser and Kashmir Cave samples could significantly influence the biogeochemical cycle and secondary metabolite production in cave habitats. In addition, the two caves were also found to be rich in biosynthetic genes, encoding bioactive compounds, such as monobactam and prodigiosin, indicating that these caves could be potential habitats for the isolation of antibiotics. This study provides a comprehensive insight into the diversity of bacteria and archaea in cave ecosystems and helps to better understand the special survival strategies of microorganisms in cave ecosystems.Key points• Geochemically distinct caves possess unique microbial community structure.• Cavernicoles could be important candidates for antibiotic production.• Cavernicoles are important for biogeochemical cycling.
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Affiliation(s)
- Sahib Zada
- Department of Biology, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, Shantou, China
| | - Jianmin Xie
- Department of Biology, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, Shantou, China
| | - Min Yang
- Department of Biology, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, Shantou, China
| | - Xiaoyu Yang
- Department of Biology, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, Shantou, China
| | - Wasim Sajjad
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Muhammad Rafiq
- Department of Microbiology, Faculty of Life Sciences and Informatics, Engineering and Management Sciences, Balochistan University of Information Technology, Quetta, Pakistan
| | - Fariha Hasan
- Department of Microbiology, Quaid-I-Azam University, Islamabad, Pakistan
| | - Zhong Hu
- Department of Biology, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, Shantou, China
| | - Hui Wang
- Department of Biology, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, Shantou, China.
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Sharma N, Kumar J, Abedin MM, Sahoo D, Pandey A, Rai AK, Singh SP. Metagenomics revealing molecular profiling of community structure and metabolic pathways in natural hot springs of the Sikkim Himalaya. BMC Microbiol 2020; 20:246. [PMID: 32778049 PMCID: PMC7418396 DOI: 10.1186/s12866-020-01923-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 07/26/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Himalaya is an ecologically pristine environment. The geo-tectonic activities have shaped various environmental niches with diverse microbial populations throughout the Himalayan biosphere region. Albeit, limited information is available in terms of molecular insights into the microbiome, including the uncultured microbes, of the Himalayan habitat. Hence, a vast majority of genomic resources are still under-explored from this region. Metagenome analysis has simplified the extensive in-depth exploration of diverse habitats. In the present study, the culture-independent whole metagenome sequencing methodology was employed for microbial diversity exploration and identification of genes involved in various metabolic pathways in two geothermal springs located at different altitudes in the Sikkim Himalaya. RESULTS The two hot springs, Polok and Reshi, have distinct abiotic conditions. The average temperature of Polok and Reshi was recorded to be 62 °C and 43 °C, respectively. Both the aquatic habitats have alkaline geochemistry with pH in the range of 7-8. Community profile analysis revealed genomic evidence of plentiful bacteria, with a minute fraction of the archaeal population in hot water reservoirs of Polok and Reshi hot spring. Mesophilic microbes belonging to Proteobacteria and Firmicutes phyla were predominant at both the sites. Polok exhibited an extravagant representation of Chloroflexi, Deinococcus-Thermus, Aquificae, and Thermotogae. Metabolic potential analysis depicted orthologous genes associated with sulfur, nitrogen, and methane metabolism, contributed by the microflora in the hydrothermal system. The genomic information of many novel carbohydrate-transforming enzymes was deciphered in the metagenomic description. Further, the genomic capacity of antimicrobial biomolecules and antibiotic resistance were discerned. CONCLUSION The study provided comprehensive molecular information about the microbial treasury as well as the metabolic features of the two geothermal sites. The thermal aquatic niches were found a potential bioresource of biocatalyst systems for biomass-processing. Overall, this study provides the whole metagenome based insights into the taxonomic and functional profiles of Polok and Reshi hot springs of the Sikkim Himalaya. The study generated a wealth of genomic data that can be explored for the discovery and characterization of novel genes encoding proteins of industrial importance.
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Affiliation(s)
- Nitish Sharma
- Center of Innovative and Applied Bioprocessing (DBT-CIAB), SAS Nagar, Mohali, India
- Department of Biotechnology, Panjab University, Chandigarh, India
| | - Jitesh Kumar
- Center of Innovative and Applied Bioprocessing (DBT-CIAB), SAS Nagar, Mohali, India
| | - Md Minhajul Abedin
- Institute of Bioresources and Sustainable Development, Sikkim Centre, Tadong, Gangtok, India
| | - Dinabandhu Sahoo
- Institute of Bioresources and Sustainable Development, Sikkim Centre, Tadong, Gangtok, India
| | - Ashok Pandey
- CSIR-Indian Institute of Toxicology Research, Lucknow, India
| | - Amit K Rai
- Institute of Bioresources and Sustainable Development, Sikkim Centre, Tadong, Gangtok, India.
| | - Sudhir P Singh
- Center of Innovative and Applied Bioprocessing (DBT-CIAB), SAS Nagar, Mohali, India.
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Riabinin G, Abd El-Aty AM, Blumberga D, Baranenko D. Alternative “Green” Antimicrobial Agents Obtained by Selective Sorption from Lactobacillus plantarum Culture. ENVIRONMENTAL AND CLIMATE TECHNOLOGIES 2020; 24:740-754. [DOI: 10.2478/rtuect-2020-0046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
Abstract
According to the world health organization report from September 2016, the development of pathogenic bacteria resistance to antimicrobial drugs is one of the most important problems of the modern medicine. In this regard, the urgent task is the search for alternative antibiotics for the treatment of bacterial infections. One approach to solving this problem is obtaining antimicrobial compounds synthesized by probiotic lactic acid bacteria. The probiotic strain of Lactobacillus plantarum 8P-A3, was chosen to study its antimicrobial action. This strain produces at least two bacteriocins – plantaricin EF and plantaricin NC8. The chromatographic isolation of peptide fractions from the supernatant was carried out using a polymer sorbent based on methacrylic acid and ethyleneglycol dimethacrylate. Optimal parameters for chromatographic process were determined. It is shown that all the target biologically active substances were bound with the sorbent in sorption at acidic pH values. Elution was performed in isocratic mode. The antimicrobial activity of the obtained peptide fractions against indicator culture was determined by turbidimetric method. During incubation process, the turbidity of the microbial suspension was determined by measuring the optical density at λ = 600 nm. It is revealed that the fraction obtained at rinse by eluent with pH 8 has the maximum inhibitory ability. Сhromatomass-spectrometry analysis of the peptide fraction was carried out using Shimadzu LCMS-8040.The antimicrobial activity of the fraction is comparable to the action of ampicillin against gram-negative bacteria Escherichia coli. To confirm the peptide nature of the antimicrobial activity of the fraction, an indicator culture was incubated with the fraction treated with proteolytic enzymes (trypsin). It is determined the fraction can be stored at −18 °C and saves antimicrobial properties after defrosting.
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Affiliation(s)
- Georgii Riabinin
- International research centre “Biotechnologies of the Third Millennium” , ITMO University , Lomonosova street 9, Saint Petersburg, Russia
| | - A. M. Abd El-Aty
- Department of Pharmacology, Faculty of Veterinary Medicine , Cairo University , 12211 - Giza , Egypt
| | - Dagnija Blumberga
- Institute of Energy Systems and Environment , Riga Technical University , Azenes iela 12/1, LV-1048 , Riga , Latvia
| | - Denis Baranenko
- International research centre “Biotechnologies of the Third Millennium” , ITMO University , Lomonosova street 9, Saint Petersburg, Russia
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Cesa-Luna C, Baez A, Quintero-Hernández V, De la Cruz-Enríquez J, Castañeda-Antonio MD, Muñoz-Rojas J. The importance of antimicrobial compounds produced by beneficial bacteria on the biocontrol of phytopathogens. ACTA BIOLÓGICA COLOMBIANA 2020. [DOI: 10.15446/abc.v25n1.76867] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Bacteria produce antimicrobial compounds to compete for nutrients and space in a particular habitat. Antagonistic interactions can be evaluated by several methodologies including the double-layer agar and simultaneous inhibition assays. Among the well-known inhibitory substances produced by bacteria are the broad-spectrum antibiotics, organic acids, siderophores, antifungal, and bacteriocins. The most studied bacterial genera able to produce these inhibitory substances are Enterococcus, Lactococcus, Streptomyces, Bacillus, Pseudomonas, Klebsiella, Escherichia, and Burkholderia. Some beneficial bacteria can promote plant growth and degrade toxic compounds in the environment representing an attractive solution to diverse issues in agriculture and soil pollution, particularly in fields with damaged soils where pesticides and fertilizers have been indiscriminately used. Beneficial bacteria may increase plant health by inhibiting pathogenic microorganisms; some examples include Gluconacetobacter diazotrophicus, Azospirullum brasilense, Pseudomonas fluorescens, Pseudomonas protegens, and Burkholderia tropica. However, most studies showing the antagonistic potential of these bacteria have been performed in vitro, and just a few of them have been evaluated in association with plants. Several inhibitory substances involved in pathogen antagonism have not been elucidated yet; in fact, we know only 1 % of the bacterial diversity in a natural environment leading us to assume that many other inhibitory substances remain unexplored. In this review, we will describe the characteristics of some antimicrobial compounds produced by beneficial bacteria, the principal methodologies performed to evaluate their production, modes of action, and their importance for biotechnological purposes.
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Purification, characterization and mode of action of enterocin, a novel bacteriocin produced by Enterococcus faecium TJUQ1. Int J Biol Macromol 2019; 144:151-159. [PMID: 31846663 DOI: 10.1016/j.ijbiomac.2019.12.090] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 11/28/2019] [Accepted: 12/11/2019] [Indexed: 12/12/2022]
Abstract
Enterococcus faecium TJUQ1 with high bacteriocin-producing ability was isolated from pickled Chinese celery. In this study, enterocin TJUQ1 was purified by ammonium sulfate precipitation, reversed-phase chromatography (Sep-Pak C8) and cation-exchange chromatography. The activity of the purified bacteriocin was 44,566.41 ± 874.69 AU/mg, which corresponds to a purification fold of 35.89 ± 2.34. The molecular mass was 5520 Da by MALDI-TOF MS and Tris-Tricine SDS-PAGE. The result of LC-MS/MS showed that the bacteriocin shared 59.15% identity with enterocin produced by E. faecium GN (accession no. O34071). PCR amplification revealed that E. faecium TJUQ1 possesses a gene encoding enterocin B with 60% identity to enterocin B. Circular dichroism (CD) spectroscopy showed that the molecular conformation was 32.6% helix, 19.5% beta, 12.9% turn and 35.0% random. The stability of enterocin TJUQ1 was measured. After exposure at 121 °C for 15 min, the residual antimicrobial activity of enterocin TJUQ1 was 85.95 ± 1.32%. The antimicrobial activity of enterocin TJUQ1 was still active over a pH range of 3-11. Enterocin TJUQ1 was inactivated after exposure to proteolytic enzymes but was not inactivated by lipase or amylase. These results showed that enterocin TJUQ1 was a novel class II bacteriocin. Enterocin TJUQ1 showed wide antibacterial activity against food-borne gram-negative and gram-positive pathogens, such as Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salmonella enterica. The MIC was 5.26 ± 0.24 μg/mL against L. monocytogenes CMCC 1595. SEM and TEM were used to observe the changes in the morphological and intracellular organization of L. monocytogenes CMCC 1595 cells treated with enterocin TJUQ1. The results demonstrated that enterocin TJUQ1 increased extracellular electrical conductivity, facilitated pore formation, triggered the release of UV-absorbing materials, ATP and LDH, and even caused cell lysis in L. monocytogenes CMCC 1595 cells. Based on the characterization, the wide inhibitory spectrum and mode of action determined so far, enterocin TJUQ1 is a potential preservative for the food industry.
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Purification and partial characterization of M1-UVs300, a novel bacteriocin produced by Lactobacillus plantarum isolated from fermented sausage. Food Control 2017. [DOI: 10.1016/j.foodcont.2017.05.030] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Sources of antibiotics: Hot springs. Biochem Pharmacol 2017; 134:35-41. [DOI: 10.1016/j.bcp.2016.11.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 11/22/2016] [Indexed: 11/17/2022]
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Antagonistic interactions and production of halocin antimicrobial peptides among extremely halophilic prokaryotes isolated from the solar saltern of Sfax, Tunisia. Extremophiles 2016; 20:363-74. [PMID: 27074936 DOI: 10.1007/s00792-016-0827-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 03/24/2016] [Indexed: 10/22/2022]
Abstract
Thirty-five extremely halophilic microbial strains isolated from crystallizer (TS18) and non-crystallizer (M1) ponds in the Sfax solar saltern in Tunisia were examined for their ability to exert antimicrobial activity. Antagonistic assays resulted in the selection of eleven strains that displayed such antimicrobial activity and they were further characterized. Three cases of cross-domain inhibition (archaea/bacteria or bacteria/archaea) were observed. Four archaeal strains exerted antimicrobial activity against several other strains. Three strains, for which several lines of evidence suggested the antimicrobial activity was, at least in part, due to peptide/protein agents (Halobacterium salinarum ETD5, Hbt. salinarum ETD8, and Haloterrigena thermotolerans SS1R12), were studied further. Optimal culture conditions for growth and antimicrobial production were determined. Using DNA amplification with specific primers, sequencing and RT-PCR analysis, Hbt. salinarum ETD5 and Hbt. salinarum ETD8 were shown to encode and express halocin S8, a hydrophobic antimicrobial peptide targeting halophilic archaea. Although the gene encoding halocin H4 was amplified from the genome of Htg. thermotolerans SS1R12, no transcript could be detected and the antimicrobial activity was most likely due to multiple antimicrobial compounds. This is also the first report that points to four different strains isolated from different geographical locations with the capacity to produce identical halocin S8 proteins.
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