Abstract This study aimed to evaluate the antibacterial activity of flavonoids extracted from two Libyan brown algae namely Cystoseira compressa and Padina pavonica using microwave-assisted extraction method against pathogenic bacteria isolated from meat, meat products, milk and dairy products (Staphylococcus aureus subsp. aureus (5 isolates), Bacillus cereus (3 isolates), Bacillus pumilus (1 isolate), Salmonella enterica subsp. enteric (4 isolates) and Enterohaemorrhagic Escherichia coli O157 (EHEC O157) (4 isolates)). All of these isolates were muti-drug resistant with high MAR index. The results showed that C. compressa extract exhibited better and stronger antibacterial activities against the seventeen tested isolates with inhibition zones diameter ranged from 14 - 22 mm compared to P. pavonica extract which showed positive effect against 9 isolates with low inhibition zone ranged from 11 - 16.5 mm. Flavonoids extracted from C. compressa also displayed the best spectrum of bactericidal effect with a ratio MBC/MIC ≤ 4 obtained on all susceptible tested bacterial strains. Flavonoids and proanthocyanidins significantly contributed to the antibacterial properties. The mode of action of these active extracts is under investigation.
Hesham Taher Naas(1-2017)

Background: This study was conducted to investigate the presence of Bacillus cereus in meat, meat products, and some seafood in Libya. Materials and Methods: One hundred and thirty‑one samples were collected from different geographic localities in Libya. The samples were subjected to microbiological analysis for enumeration and isolation of B. cereus by conventional cultural, biochemical, and molecular identification using polymerase chain reaction (PCR) and partial sequencing of 16S rDNA techniques. Results: Of 131 samples, only 38 (29%) isolates were found to be B. cereus based on their cultural characteristics on Mannitol Egg‑Yolk Polymyxin (MYP) medium that included 30% beef, 38.2% beef products (minced, burger, kabab, and sausage), 31.8% camel meat, and 48% chicken products (burger, sausage, kabab, and liver). However, B. cereus was not detected from mutton and seafood samples. Seventeen isolates were subjected to molecular identification using PCR and partial sequencing of 16S rDNA technique and confirmed to be B. cereus. The confirmed B. cereus strains were tested for their antibiotic sensitivity profiles and showed a high percentage of multiresistance phenotype. Conclusions: The results provide a better understanding of B. cereus isolated from food of animal origin in Libya and suggest that meat and meat products might play an important role in the spreading of B. cereus through the food chain with antimicrobial resistance characteristics.
Hesham Taher Naas(6-2018)

The objective of this study was to evaluate the effect of nisin in combination with different types of packaging on the survival of Listeria monocytogenes in ready-to-eat low-fat turkey bologna. Bologna was inoculated with L. monocytogenes exposed to 1 of 6 treatments: 3 packaging treatments (100% CO2, air, vacuum), each with and without nisin. Bologna was refrigerated and sampled 9 times over 42 d. Nisin reduced initial L. monocytogenes populations by 1.5 to 2 log cycles and 100% CO2 packaging prevented outgrowth throughout 42 d of storage, whereas non-CO2 packaging displayed a 2-log increase in population during storage. Nisin (500 IU/mL) combined with 100% CO2 was effective in reducing Listeria and preventing outgrowth on bologna over 42 d of refrigerated storage.
Hesham Taher Naas(3-2013)