11 research outputs found

    Determination of cadmium, lead and mercury residual levels in meat of canned light tuna (Katsuwonus pelamis and Thunnus albacares) and fresh little tunny (Euthynnus alletteratus) in Libya

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    Surveillance for mercury (Hg), lead (Pb) and cadmium (Cd) contamination in tuna products is crucial for consumer food safety. Hg, Pb and Cd contaminants were monitored in a total of 60 specimens of fresh little tunny (Euthynnus alletteratus) and popular brands of skipjack and yellowfin (Katsuwonus pelamis and Thunnus albacares) canned tuna commercially available in Tripoli, Libya. Direct Mercury Analyzer (DMA-80) was implemented for determination of total Hg level and graphite furnace atomic absorption spectrometry (GFAAS) was employed for determination of Cd and Pb concentrations. The results indicated that Hg had the highest concentration level and Cd had the lowest concentration level either in tested canned tuna or fresh little tunny samples. The average concentration of Hg in fresh little tunny samples was 1.185 ± 0.968 mg kg-1 wet weight (ww) and often exceeded the standard permissible limit. In addition, canned yellowfin tuna had the lowest levels of Cd (0.027 ± 0.026 mg kg-1 ww), Pb (0.075 ± 0.071) and Hg (0.163 ± 0.122 mg kg-1 ww). Results of the current surveillance indicated that canned skipjack and yellowfin tuna sold in Tripoli markets show contaminant levels well under the European thresholds adopted for Cd, Pb and Hg. However, consumption of large quantities of Mediterranean little tunny products significantly increases human exposure to the risk of Hg toxicity.Keywords: Cadmium, Canned tuna, Lead, Little tunny, Mercury

    Determination of cadmium, lead and mercury residual levels in meat of canned light tuna (Katsuwonus pelamis and Thunnus albacares) and fresh little tunny (Euthynnus alletteratus) in Libya

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    Surveillance for mercury (Hg), lead (Pb) and cadmium (Cd) contamination in tuna products is crucial for consumer food safety. Hg, Pb and Cd contaminants were monitored in a total of 60 specimens of fresh little tunny (Euthynnus alletteratus) and popular brands of skipjack and yellowfin (Katsuwonus pelamis and Thunnus albacares) canned tuna commercially available in Tripoli, Libya. Direct Mercury Analyzer (DMA-80) was implemented for determination of total Hg level and graphite furnace atomic absorption spectrometry (GFAAS) was employed for determination of Cd and Pb concentrations. The results indicated that Hg had the highest concentration level and Cd had the lowest concentration level either in tested canned tuna or fresh little tunny samples. The average concentration of Hg in fresh little tunny samples was 1.185 ± 0.968 mg kg-1 wet weight (ww) and often exceeded the standard permissible limit. In addition, canned yellowfin tuna had the lowest levels of Cd (0.027 ± 0.026 mg kg-1 ww), Pb (0.075 ± 0.071) and Hg (0.163 ± 0.122 mg kg-1 ww). Results of the current surveillance indicated that canned skipjack and yellowfin tuna sold in Tripoli markets show contaminant levels well under the European thresholds adopted for Cd, Pb and Hg. However, consumption of large quantities of Mediterranean little tunny products significantly increases human exposure to the risk of Hg toxicity

    Raw cow’s milk relatively inhibits quorum sensing activity of Cromobacterium violaceum in comparison to raw she-camel’s milk

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    Milk from different animal species has variable levels of antimicrobial factors against some of spoilage bacteria. For example, they are significantly present in higher concentration in she-camel’s milk than in cattle or buffalo and they are more heat-resistant than their counterparts in cattle and buffalo. Spoilage bacteria are known to communicate with each other by release of signaling molecules, a phenomenon described as quorum sensing (QS). Some food matrices inhibit these signaling compounds. In this study we screened QS inhibitory activities in raw milk of cattle and camel. Ten samples each of fresh raw cow’s milk and she-camel’s milk from apparently healthy animals were screened using the bacterial model Cromobacterium violaceum. The tested cow’s raw milk samples were able to inhibit the production of QS signalling molecules acyl-homoserine lactones (AHLs) produced by C. violaceum. However, she-camel’s milk samples were less effective in inhibiting such AHLs. Thus, one of the factors which influence the inhibitory activity could be derived from variation in milk chemical composition, especially in the percentage of fat which is significantly higher in tested cow’s milk samples (2.22±0.12) than in tested she-camel’s milk samples (1.44±0.35). Natural inhibition of QS signaling by cow’s milk may offer a unique means to control foodborne pathogens and reduce microbial spoilage.Keywords: Quorum, Sensing, Inhibition, Cromobacterium violaceum, Mil

    Antibacterial effect of olive (Olea europaea L.) leaves extract in raw peeled undeveined shrimp (Penaeus semisulcatus)

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    Olive (Olea europaea L.) leaves are rich in phenolic substances, which exert important antioxidant and antibacterial effects. In this study, the effect of olive leaves extract (OLE) on the microbial load of raw peeled undeveined (PUD) shrimp (Penaeus semisulcatus) was evaluated. Alcoholic OLE extracts were prepared at 0.5%, 1% and 2% (w/v) concentrations. Raw PUD shrimp samples were immersed in the treatment solutions for 3 h at 4 °C and samples were taken for determination of total viable count (TVC) and total coliforms count (TCC). OLE at concentration of 1% (w/v) significantly (p < 0.01) reduced the count of the aerobic and coliforms bacteria at least 1 log cycle CFU/g in reference to the non-treated control group. Such antimicrobial activity was concentration dependent and usage of 2% OLE had the most beneficial effect in controlling microbial load in PUD shrimp stored at 4 °C. This study demonstrates the potential use of OLE formulations to improve the microbial quality of PUD shrimp and OLE might be useful to the seafood industry as a natural preservative

    Attenuated virulence of pigment-producing mutant of Aeromonas veronii bv. sobria in HeLa cells and Nile tilapia (Oreochromis niloticus)

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    Aeromonas species are potential water/foodborne pathogens, whereas Aeromonas veronii bv. sobria is one of the most virulent species to human and fish. Most current experimental evidence has publicized that suicide plasmid dependent IS1-element untargeted integration into A. veronii bv. sobria ATCC 9071T strain was recently used to generate brown pigment-producing and spontaneous pelleting (BP+SP+) mutant. Current study was conducted to compare virulence of wild-type ATCC 9071T strain and its BP+SP+ mutant with respect to cytotoxicity in HeLa cells and lethality in Nile tilapia. It was found that the cytotoxicity of wild-type ATCC 9071T strain to HeLa cells has reached 75% versus 50% for the cytotoxicity of BP+SP+ mutant. Further, the median lethal dose (LD50) of wild-type ATCC 9071T strain in Nile tilapia was 8.25 Log10 colony-forming units (CFU)/ml, compared to 9.16 Log10 CFU/ml for the LD50 of BP+SP+ mutant. Thus, current study supports the notion that non pigment-producing Aeromonas strains are more virulent than pigment-producing ones

    Isolation and molecular identification of Vibrio spp. by sequencing of 16S rDNA from seafood, meat and meat products in Libya

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    The genus Vibrio includes several food-borne pathogens that cause a spectrum of clinical conditions including septicemia, cholera and milder forms of gastroenteritis. Several Vibrio spp. are commonly associated with food-borne transmission including Vibrio cholerae, Vibrio parahemolyticus, and Vibrio vulnificus. Microbiological analysis for enumeration and isolation of Vibrio spp. were carried out for a total of 93 samples of seafood, meat and meat products from different geographic localities in Libya (Tripoli, Regdalin, Janzour and Tobruk). Vibrio spp. were detected by conventional cultural and molecular method using PCR and sequencing of 16S rDNA. Out of the 93 cultured samples only 48 (51.6%) yielded colonies on Thiosulfate Citrate Bile Salt agar (TCBS) with culture characteristics of Vibrio spp. More than half (n=27) of processed seafood samples (n=46) yielded colonies on TCBS, while only 44.6% of samples of meat and meat products showed colonies on TCBS. Among cultured seafood samples, the highest bacterial count was recorded in clam with a count of 3.8 Ń…104 CFU\g. Chicken burger samples showed the highest bacterial count with 6.5 Ń…104 CFU\g. Molecular analysis of the isolates obtained in this study, showed that 11 samples out of 48 (22.9%) were Vibrio spp. Vibrio parahemolyticus was isolated from camel meat for the first time. This study is an initial step to provide a baseline for future molecular research targeting Vibrio spp. foodborne illnesses. This data will be used to provide information on the magnitude of such pathogens in Libyan seafood, meat and meat products.Keywords: 16S rDNA, Libya, Meat, Seafood, Vibri

    Extent of pathogenic and spoilage microorganisms in whole muscle meat, meat products and seafood sold in Libyan market

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    Background: Whole muscle meat, meat products, and seafood contain different nutrients in adequate quantity providing a better environment for presence and replication of different microorganisms. There are underreporting and inaccurate estimation of foodborne diseases due to the lack of effective surveillance systems in Libya. Aim: To determine the extent of microbiological contamination of whole muscle meat, meat products and seafood. Methods: A total number of 731 samples of retail meat were collected from different stores in four cities in Libya. Samples were analyzed for aerobic plate count (APC), and subjected to microbiological enumeration and isolation techniques, followed by molecular identification by PCR and partially sequencing of 16S rDNA. Results: The results showed contamination of samples with enteric and spoilage bacteria. Fifteen genera of spoilage bacteria yielded 149 isolates were detected and identified by PCR and partially sequencing of 16S rDNA as: Proteus spp., Provedencia spp., Raouttella ornithinolytical, Citrobacter spp., Enterobacter spp., Morganella morgi, Shewanella algea, Rhodobacter capsulatus, Listonella pelagia, Kluyvera spp., Pectobacterium spp., Brenneria spp., Klebsiella spp., Acintobacter radioresistens, and Pantoea spp. While for pathogenic bacteria, 143 isolates distributed among nine genera were identified by PCR and partially sequencing of 16S rDNA as: Bacillus spp., Escherichia spp., Shigella spp., Enterococci spp., Cronobacter spp., Staphylococci spp., Salmonella spp., Aeromonas spp., and Vibrio spp.. Many isolated bacteria are zoonotic bacteria with high importance for public health. Conclusion: Excessive handling and processing of meat and meat products seems to be one of the poorest microbiological quality. These findings ought to be helpful in risk assessments and quality assurance of meat in order to improve food safety

    Occurrence, characterization, and antibiogram of Staphylococcus aureus in meat, meat products, and some seafood from Libyan retail markets

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    Aim: The aim of the current investigation was to screen the presence of Staphylococci spp., especially S. aureus in meat, meat products of different animal species, and some seafood sold in some retail markets in Libya using cultural and molecular techniques, and to study their antibiotics resistance profiles. Materials and Methods: A total of 139 samples from red meat, meat products, and seafood were collected from many areas in Libya. Enumeration and isolation of Staphylococci spp. and S. aureus by normal cultural methods followed by molecular identification using molecular techniques by bacterial DNA extraction and partial sequencing of 16S rDNA. Results: Out of 139 samples, 112 (80.6%) were contaminated with different species of Staphylococci based on cultural characteristics of Staphylococci on Baird-Parker medium, for which S. aureus was detected in only 32 samples (23%). However, only six out of 18 (33.3%) isolates sent for sequencing were confirmed to be S. aureus using the molecular technique. The six identified isolates of S. aureus were tested for antimicrobial resistance against 24 most commonly used antibiotics. All isolates were resistant to only two antibiotics (cefotaxime and clindamycin). Among these six isolates, only one confirmed to be Methicillin-resistant Staphylococcus aureus. Conclusion: Results of this study suggest that food of animal origin could be a source of S. aureus with antimicrobial resistance characteristics that can be spread through the food chain, and raise the importance of these results for public health

    Enterohemorrhagic Escherichia coli O157 in milk and dairy products from Libya: Isolation and molecular identification by partial sequencing of 16S rDNA

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    Aim: The aim of this work was to isolate and molecularly identify enterohemorrhagic Escherichia coli (EHEC) O157 in milk and dairy products in Libya, in addition; to clear the accuracy of cultural and biochemical identification as compared with molecular identification by partial sequencing of 16S rDNA for the existing isolates. Materials and Methods: A total of 108 samples of raw milk (cow, she-camel, and goat) and locally made dairy products (fermented cow’s milk, Maasora, Ricotta and ice cream) were collected from some regions (Janzour, Tripoli, Kremiya, Tajoura and Tobruk) in Libya. Samples were subjected to microbiological analysis for isolation of E. coli that was detected by conventional cultural and molecular method using polymerase chain reaction and partial sequencing of 16S rDNA. Results: Out of 108 samples, only 27 isolates were found to be EHEC O157 based on their cultural characteristics (Tellurite-Cefixime-Sorbitol MacConkey) that include 3 isolates from cow’s milk (11%), 3 isolates from she-camel’s milk (11%), two isolates from goat’s milk (7.4%) and 7 isolates from fermented raw milk samples (26%), isolates from fresh locally made soft cheeses (Maasora and Ricotta) were 9 (33%) and 3 (11%), respectively, while none of the ice cream samples revealed any growth. However, out of these 27 isolates, only 11 were confirmed to be E. coli by partial sequencing of 16S rDNA and E. coli O157 Latex agglutination test. Phylogenetic analysis revealed that majority of local E. coli isolates were related to E. coli O157:H7 FRIK944 strain. Conclusion: These results can be used for further studies on EHEC O157 as an emerging foodborne pathogen and its role in human infection in Libya
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