Modeling inhibitory activity of a novel antimicrobial peptide AMPNT-6 from Bacillus subtilis against Vibrio parahaemolyticus in shrimp under various environmental conditions

Food Control ◽  
2013 ◽  
Vol 33 (1) ◽  
pp. 249-253 ◽  
Author(s):  
Yuehua Pu ◽  
Lijun Sun ◽  
Yaling Wang ◽  
Deng Qi ◽  
Danmin Chen ◽  
...  
2020 ◽  
Author(s):  
Sarah E. Avery ◽  
Susannah P. Ruzbarsky ◽  
Amanda M. Hise ◽  
Harold J. Schreier

ABSTRACTAcute hepatopancreatic necrosis disease (AHPND) is caused by PirAB toxin-producing Vibrio parahaemolyticus and has devastated the global shrimp aquaculture industry. One approach for preventing growth of AHPND-producing Vibrio spp. is through the application of beneficial bacteria capable of inhibiting these pathogens. In this study we focus on the inhibitory activity of Bacillus subtilis subsp. inaquosorum strain T1, which hinders V. parahaemolyticus growth in co-culture experiments in a density-dependent manner; inhibition was also obtained using cell-free supernatants from T1 stationary phase cultures. Using a mariner-based transposon mutagenesis, 17 mutants were identified having complete or partial loss of inhibitory activity. Of those having total activity loss, 13 had insertions within a 42.6 kb DNA region comprising 15 genes whose deduced products were homologous to non-ribosomal polypeptide synthetases (NRPSs), polyketide synthases (PKSs) and related activities, which were mapped as one transcriptional unit. Mutants with partial activity contained insertions in spo0A and oppA, indicating stationary phase control. Expression of lacZ transcriptional fusions to NRPS and PKS genes was negligible during growth and at their highest during early stationary phase. Inactivation of sigH resulted in loss of inhibitor activity, indicating a role for σH in transcription. Disruption of abrB resulted in NRPS and PKS gene overexpression during growth as well as enhanced growth inhibition. This is the first study examining expression and control of an NRPS-PKS region unique to the inaquosorum subspecies of B. subtilis and an understanding of factors involved in T1 inhibitor production will enable its development for use as a potential tool against AHPND Vibrio pathogens in shrimp aquaculture.IMPORTANCEThe shrimp aquaculture industry has been impacted by the rise of acute hepatopancreatic necrosis disease (AHPND), resulting in significant financial losses annually. Caused by strains of the bacterial pathogen, Vibrio parahaemolyticus, treatment of AHPND involves the use of antibiotics, which leads to a rise in antibiotic resistant strains. An alternative approach is through the application of beneficial microorganisms having inhibitory activities against AHPND-generating pathogens. In this study, we examine the genetic basis for the ability of Bacillus subtilis strain T1 to inhibit growth of an AHPND Vibrio strain and show that activity is associated with genes having the potential for synthesizing antibacterial compounds. We found that expression of these genes is under stationary phase control and showed that inactivation of a global transition state regulator results in enhancement of inhibitory activity against the AHPND Vibrio. Our approach for understanding the factors involved in production B. subtilis strain T1 inhibitory activity may allow for development of this strain for use as a potential tool for the prevention of AHPND outbreaks.


2019 ◽  
Vol 9 (02) ◽  
Author(s):  
Hussein A Kadhum ◽  
Thualfakar H Hasan2

The study involved the selection of two isolates from Bacillus subtilis to investigate their inhibitory activity against some bacterial pathogens. B sub-bacteria were found to have a broad spectrum against test bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa. They were about 23-30 mm and less against Klebsiella sp. The sensitivity of some antibodies was tested on the test samples. The results showed that the inhibitory ability of bacterial growth in the test samples using B. subtilis extract was more effective than the antibiotics used.


Author(s):  
Nguyễn Thị Bích Đào ◽  
Trần Quang Khánh Vân ◽  
Nguyễn Văn Khanh ◽  
Nguyễn Quang Linh

Khi tình hình bệnh hội chứng tôm chết sớm (EMS) đã gây thiệt hại vô cùng to lớn đối với Nuôi trồng thủy sản thì các giải pháp được đề nghị và áp dụng nhằm hạn chế dịch bệnh. Trong đó, việc tìm hiểu và đưa vi khuẩn có lợi để cạnh tranh và ức chế loài vi khuẩn gây bệnh rất được quan tâm, được cho là giải pháp có nhiều triển vọng phù hợp với điều kiện môi trường, đảm bảo sức khỏe cho con người, cũng như hạn chế được dịch bệnh. Đặc biệt, đưa vi khuẩn Bacillus spp. qua đường tiêu hóa của tôm ngay từ khi mới thả đã hạn chế được mật độ vi khuẩn Vibrio. Nghiên cứu này đã phân lập được các chủng Bacillus subtilis B1, Bacillus subtilis B2, Bacillus amyloliquefaciens B4và thử khả năng đối kháng với vi khuẩn Vibrio parahaemolyticus V1 ở các nồng độ 103, 104, 105, 106 CFU theo dõi ở các thời điểm 6h, 12h, 24h, 48h và 72h. Kết quả cho thấy cả ba chủng vi khuẩn Bacillus trên phân lập được đều có khả năng ức chế tốt vi khuẩn Vibrio parahaemolyticus V1, trong đó vi khuẩn Bacillus amyloliquefaciens B4 làtốt nhất với đường kính vòng kháng khuẩn 52,67 ± 4,31mm ở thời điểm 48h; hai chủng Bacillus subtilis B1, Bacillus subtilis B2 lầnlượt là  49,67 ± 3,15 mm, 44,07 ± 5,19 mm, với mức sai số có ý nghĩa thống kê p < 0,05.


Author(s):  
Umeh Odera Richard ◽  
E. I. Chukwura ◽  
Ibo Eziafakaego Mercy

A fish pond with recommended water quality will produce healthy fishes. Fish ponds with poor water quality will cause fish mortality and outbreak of diseases to fish consumers. Physicochemical analysis was done using standard analytical methods, the total bacterial count was determined by dilution and membrane filtration techniques. Parasitological analysis was done using the centrifugation method. A total of fifteen well waters were sampled during wet season. Results showed that the temperature ranged from 27°C to 29°C, pH, 6.21 to 8.15; dissolved oxygen, 4.28 mg/l to 5.78 mg/l, electrical conductivity, 166.36 µs/cm to 394.00 µs/cm; total dissolved solids, 41 mg/l to 121 mg/l; total suspended solids, 1.00 mg/l to 19.40 mg/l; total solids, 42.00 mg/l to 140.4 mg/l; turbidity values, 7.01 NTU to 10.36 NTU; nitrate, 3.10 mg/l to 28.00 mg/l; total alkalinity, 36 mg/l to 91 mg/l; phosphate, 1.26 mg/l to 13.11 mg/l; sulphate, 0.39 mg/l to 4.37 mg/l; total chloride, 7.08 mg/l to 14.19 mg/l; carbonates, 1.33 mg/l to 2.35 mg/l; bicarbonates, 34.59 mg/l to 89.38 mg/l; total hardness, 25.31 mg/l to 53.04 mg/l; calcium hardness, 23.94 mg/l to 51.96 mg/l; magnesium hardness, 1.08 mg/l to 4.20 mg/l; total acidity, 2 mg/l to 22 mg/l; potassium, 0.04 mg/l to 2.23 mg/l; cadmium, 0.00 mg/l to 0.04 mg/l; lead, 0.01 mg/l - 0.16 mg/l; chromium, 0.00 mg/l - 0.03 mg/l; mercury was not detected, copper, 0.00 mg/l - 0.04 mg/l; arsenic, 0.00 mg/l - 0.02 mg/l; zinc, 0.00 mg/l to 0.02 mg/l; iron, 0.01 mg/l - 1.19 mg/l. The total bacterial counts ranged from 3.60-4.12 log cfu/ml; total coliforms, 14-46 cfu/100ml, Vibrio cholerae, 0-11 cfu/100ml; Vibrio parahaemolyticus, 0-15 cfu/100ml; faecal coliform, 1-9 cfu/100 ml; Acinetobacter calcoaceticus, 0-8 cfu/100 ml; Bacillus subtilis, 0-9 cfu/ml; Staphylococcus aureus, 0-5 cfu/ml; Pseudomonas aeruginosa, 0-12 cfu/100 ml; Pseudomonas fluorescens, 0-12 cfu/100 ml and Clostridium perfringens were not detected in any of the samples. Twelve bacterial species namely Klebsiella pneumoniae, Acinetobacter calcoaceticus, Escherichia coli, Staphylococcus aureus, Vibrio cholerae, Pseudomonas fluorescens, Pseudomonas aeruginosa, Proteus mirabilis, Vibrio parahaemolyticus, Bacillus subtilis, Shigella flexineri and Salmonella typhi were isolated and identified using standard analytical and molecular procedures. Parasites identified were Ichthyobodo species, Diplostomum species, Myxobolus species, Chilodonella species, Bothriocephalus species, Ambiphrya species and Leech species. Salmonella typhi had the highest frequency of isolation (20.63%) while Acinetobacter calcoaceticus and Staphylococcus aureus had the lowest frequency of isolation (2.83%). Ichthyobodo species had the highest frequency of isolation (21.43%) while Leech species had the lowest frequency of isolation (5.71%). Some of the physicochemical, bacteriological and parasitological parameters had values above World Health Organization admissible limits and therefore proper sanitary practices and water treatments must be employed to prevent epidemic among fish consumers.


2006 ◽  
Vol 69 (5) ◽  
pp. 1040-1045 ◽  
Author(s):  
CHIA-HSIN JU ◽  
P. S. MARIE YEUNG ◽  
JESSICA OESTERLING ◽  
DANIEL A. SEIGERMAN ◽  
KATHRYN J. BOOR

Since 1996, Vibrio parahaemolyticus serotype O3:K6 and closely related strains have been associated with an increased incidence of V. parahaemolyticus gastroenteritis worldwide, suggesting the emergence of strains with enhanced abilities to cause disease. One hypothesis for the recent emergence of V. parahaemolyticus O3:K6 and related strains is an enhanced capacity for environmental survival relative to other strains, which might result in increased human exposure to these organisms. Therefore, the objective of this study was to test the hypothesis that survival or growth characteristics of clinical V. parahaemolyticus isolates differ from those of nonclinical isolates under different environmental conditions. Twenty-six V. parahaemolyticus isolates selected to represent either clinical or food sources were monitored for either survival following exposure to high magnesium (300 mM) or growth under iron-limited conditions. Isolates in each category (clinical or food) differed widely in survival capabilities following 24 h of exposure to 300 mM Mg2+. Although 4 of 15 clinical isolates grew better at approximately 0.96 μM Fe2+ (iron-limited conditions) than at 50 μM Fe2+ (iron-rich conditions), as an entire group clinical isolates in this study were not more effective at growing under iron-limited conditions than were strains not associated with disease. Within the diverse collection of strains examined in these experiments, neither growth characteristics in low-iron environments nor survival capabilities following exposure to high magnesium concentrations were uniformly different between clinical and nonclinical V. parahaemolyticus isolates. Therefore, neither phenotypic characteristic can be used to reliably differentiate potentially pathogenic V. parahaemolyticus strains.


1990 ◽  
Vol 54 (5) ◽  
pp. 1289-1290 ◽  
Author(s):  
San-Lang WANG ◽  
Sawao MURAO ◽  
Motoo ARAI

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