Molecular investigation of prevalence, phenotypic and genotypic diversity, antibiotic resistance, frequency of virulence genes and genome sequencing in Pseudomonas aeruginosa strains isolated from lobster.

AIM: Aquatic organisms are too susceptible to the increased growth of bacterial contamination. It seems that preventive measures should be prioritized to reduce bacterial load, and improve the health situation of marine-based product consumers. Hence, this study is aimed at molecular investigation of the prevalence of Pseudomonas aeruginosa as one of the most food-borne pathogens, antibiotic resistance, and virulence factor encoding gens in lobster samples. METHODOLOGY: After the collection of aquatic samples from Isfahan and Chabahar city during the summer and autumn seasons, they were cultured, and confirmed by biochemistry tests. Then, they were investigated for antibiotic resistance by the Kirby Bauer method. Then, antibiotic resistance, virulence factor encoding genes, and Multi-Drug Resistance (MDR) patterns were analyzed. Statistical analysis was done by SPSS through chi-square tests. RESULTS: Bacterial contamination in samples taken from Isfahan city was higher than in Chabahar city despite having a cooler climate on summer days. Antibiotic resistance to piperacillin in fresh shrimp samples taken in summer In Isfahan city was contrary to its usage as a front-line antibiotic agent for Pseudomonas aeruginosa. Lowered MDR pattern in frozen samples, was related to the varied expression of antibiotic resistance, highlighting the importance of regulations for cold chain in storage, transportation, and distribution of marine samples, especially when compared to fresh shrimps. CONCLUSION: Food-borne pathogens, antibiotic resistance, and their virulence factors are of clinical and environmental importance. Results of our study indicated a high rate of frequency for Pseudomonas aeruginosa isolated from marine samples, antibiotic resistance, antibiotic resistance encoding genes, virulence factors encoding genes, and MDR. Maintenance of the cold chain, and proper food processing, have indispensable roles in the preservation, and reduction of Pseudomonas aeruginosa frequency in aquatic organisms.

Antibacterial effects of extracted corn zein with garlic extract-based nanoemulsion on the shelf life of Vannamei prawn (Litopenaeus vannamei) at refrigerated temperature.

BACKGROUND: Litopenaeus vannamei is one of the most perishable foods due to microorganism growth. Using essential oil-based nanoemulsion as a biodegradable and edible coating can enhance the shelf life of shrimp at refrigerated temperature through retarding microbial growth compared to synthetic coatings. METHODS: Zein was extracted from 50 g dry milled corn with ethanol. Garlic essential oil was prepared by mixing with Tween 80. Nanoemulsion was prepared in an ultrasonic bath. DLS analysis, turbidity, and stability of nanoemulsions were performed. Radical scavenging activity, and total phenol content were done for evaluation of garlic essential oil and nanoemulsion. A 10% zein solution was prepared using ethanol 95% and glycerol plasticizer (2.5%). In the end, various microbial analysis, peroxide value, the thiobarbituric acid reactive substance (TBARS) value, the total volatile basic nitrogen (TVB-N) values, and sensory evaluations of different shrimp samples were determined. RESULTS: Corn zein along with garlic-based nanoemulsion, had a great impact on the TVB-N, TBARS, and peroxide value (which indicated that z+24% garlic nanoemulsion group was the lowest among other groups on days 3, 7, and 14 (p < 0.05) as well as microbial properties (garlic EO nanoemulsion had significantly better antibacterial effectiveness compared to other groups (p < 0.05)), and sensory evaluation (the z+24% garlic nanoemulsion sample received a significantly higher score than other groups (p < 0.05)) of Litopenaeus vannamei. CONCLUSIONS: Corn zein nanoemulsion functioned as an antioxidant and antimicrobial agent, increasing the shelf life of Litopenaeus vannamei at refrigerated temperature. PRACTICAL APPLICATION: Emerging nanotechnology-based approaches with no side-effects on immune system of consumers plays a vital role in bioactive packaging, and on reduction of food spoilage or food poisoning in the transportation, exporting, and distribution stages of food products, especially marine-based products with cold chain transportation. Additionally, it can reduce aquaculture and environmental risks due to the usage of chemical agents used in packaging. Our results showed that administration of a corn zein with nanoemulsion of garlic extract can prolong shelf life of Litopenaeus vannamei. The paper should be of interest to readers such as food microbiologists, aquaculture scientists, fisheries scientists, marine biologists, biomaterial scientists, food packaging industrialists, medical microbiologists, public health managers, and health system managers.