Digital Repository for University of Tripoli

Algal alkaloids are widely used for their pharmacological properties as antimicrobial agents. This study determined the antibacterial activities of algal alkaloid-rich extracts against isolates of multidrug-resistant Staphylococcus aureus and enterohaemorrhagic Escherichia coli (EHEC) O157, as well as the probable mode of action underlying their antibacterial effect. The total alkaloids were extracted from two Libyan brown algae, namely Sargassum hornschuchii and Cystoseira compressa and tested against six different isolates from the bacteria mentioned above using the agar-well diffusion method, and their mode of action on isolates was evaluated by several bacterial physiological indicators, including intracellular potassium ion efflux and nucleotide leakage. Also, the extracts' hemolytic activity was assessed as an indicator of their cytotoxicity on red blood cells. Although not to the same extent, both alkaloid extracts presented antibacterial activities against all tested isolates with no evidence of bacterial regrowth. The alkaloid extract from S. hornschuchii exerted the best effect on bacteria growth with minimum inhibitory concentration values ranging between 125 and 500 mg/mL. The results showed that the alkaloid extracts significantly induced a distinct release of nucleotide and potassium ions out of the cell membrane, indicating that they cause a change in the fluidity or permeability or both of the cell membrane. Moreover, the results revealed that there were very low cytotoxic effects. Therefore, algal alkaloids may contribute to the development of potential antibacterial agents in the future.
Salah M. Azwai(1-2021)

Background and Aim: Foodborne illnesses are a serious challenge to human health and the economic sector. For example, salmonellosis remains a burden in developed and developing nations. Rapid and reliable molecular methods to identify Salmonella strains are essential for minimizing human infection. This study aimed to identify Salmonella spp. in raw milk and dairy products using conventional and molecular techniques and to test the antibiotic susceptibility of the isolated strains. Materials and Methods: One hundred and thirty-one milk and dairy product samples were randomly collected from different localities in Libya. Samples were examined for the presence of Salmonella by conventional culture techniques, including cultivation in Rappaport-Vassiliadis broth and streaking on xylose lysine deoxycholate agar. Identification also used polymerase chain reaction and partial sequencing of 16S rDNA. Twenty-four antibiotics were used for the examination of antimicrobial resistance of Salmonella spp. isolates with the agar disk diffusion method (Kirby–Bauer technique). Multi-antibiotic resistance index and antibiotic resistance index (ARI)for Salmonella enterica isolates were calculated. Results: Twenty-one of 131 samples (16%) were positive for Salmonella spp. recovered from 9 (16%), 2 (11%), 4 (22.2%), and 6 (46%) samples of raw cow milk, fermented raw milk, and fresh locally made soft cheeses, Maasora and Ricotta), respectively. Samples of ice cream, milk powder, and infant formula showed no Salmonella spp. contamination. Only 9 of 21 (42.8%) isolates were confirmed as S. enterica by partial sequence 16S rDNA analysis. All isolates were resistant to amoxycillin, bacitracin, penicillin G, lincomycin, vancomycin, clindamycin,
Salah M. Azwai(5-2022)

Background & aim: There is significant evidence indicating that endocrine disrupted bisphenol A (BPA) seriously endangers human health. In males, BPA affects testis architecture and sperm quality, and ultimately reduces fertility. This study explored the therapeutic potential of Nigella sativa (NS) seed extract on testis and sperm abnormalities in BPA-exposed mice and characterized the underlying mechanism. Methods: Forty male Swiss albino mice (5.5 weeks old, N = 8 per group) were randomly divided into five groups: Group I, normal control, Group II, vehicle control (sterile corn oil); Group III, NS-exposed (oral 200 mg/kg); Group IV, BPA-exposed (oral 400 μg/kg body weight); Group V, BPA + NS-exposed mice. Animals were treated for 6 weeks and sacrificed for biochemical and histological examination. Results: The results indicated that BPA exposure results in significant testis and sperm abnormalities. Specifically, BPA promoted a marked reduction in the body and testis compared with the control group. Histopathological findings showed that BPA caused a widespread degeneration of spermatogenic cells of the seminiferous epithelium, decreased sperm counts and motility, and augmented sperm abnormalities, and whereas little alteration to sperm DNA was observed. In addition, BPA increased the levels of the lipid peroxidation marker, malondialdehyde (MDA), and reduced the levels of the antioxidant marker, reduced glutathione (GSH). Treatment with NS oil extract during BPA exposure significantly alleviated testis and sperm abnormalities, reduced MDA levels, and enhanced GSH levels. Conclusions: The results demonstrate that NS oil protects mice against BPA-induced sperm and testis abnormalities, likely by suppressing levels of the oxidative stress marker, MDA, and enhancing the levels of the antioxidant marker, GSH.
Mohamed A M Al Griw (5-2022)

The study presents results obtained by examination of cloacal swabs from poultry for the presence of verotoxigenic stains of E.coli O157:H7. Twenty samples (9.2%0 of 216 samples examined were positive for E.coli O157. Out of the twenty E.coli O157, 19 strains were positive for the production of both verotoxins (V1 and V2). However, none of them was positive for the presence of H7 antigen.
Hesham Taher Naas(1-2022)

Abstract Overall equipment effectiveness (OEE) is a well-accepted measure of performance in industry. In this thesis, the components of OEE were calculated over a period of 28 months using failure and repair data gathered from food and beverages packaging line. The failure and repair data of the packaging line were statistically analyzed to understand the nature of the failure patterns, and to estimate the reliability and maintainability characteristics of the packaging line in precise quantitative terms, moreover, the best fit distribution for TBF and TTR based on failure data were computed, these distributions were included in the simulation model to describe the reliability behavior of the packaging line. Among the techniques to tackle maintenance and reliability issues, simulation can undoubtedly play an important role as it provides what-if analysis and hence help to evaluate quantitative benefits. This thesis also describes the modelling of machine breakdown behavior in industrial machines, a packaging line machines in the Aseptic Liquid Food (ALF) factory. The model also examines three important scheduled tasks (parameters) influence on packaging machines to study the correlation between these parameters and the occurrence of breakdown. Results show that the component Availability of the OEE metric should be improved to optimise the productivity and the efficiency of the line. the model results of failure time metrics (i.e. MTBF and MTTR) were validated using Output Analyzer template within Arena simulation software; and the results were near actual figures of collected data. The results of second experiment model showed a decrease in breakdown occurrences compared to first experiment, however, the scheduled tasks usage rate didn't correlate to breakdown occurrences, indicating the need to study and analyze different possible reasons of breakdown occurrence. Keywords: TPM, WCM, OEE, Simulation and modelling
Tajedeen Ramadan Own(1-2022)

يعتمد البحث على اجراء دراسة للمركبات الليبدية التي لها دورا مهما في حياة الانسان كمادة غذائية غنية باطاقة و في المنتجات المختلفة الشائعة كصناعة الصابون والمنظفات الصناعية و مواد التجميل و صناعة حبر لطابعة و لأهمية الليبديات تم تحليل عشر عينات من الدهون و الزيوت الحيوانية و النباتية و دهن الزبدة ودهن البقر (بالعلف المحلي و بدون علف )زيت الزيتون المحلي و زيت الذرة corn oil ،وزيت عباد الشمس sun flower وزيت الكتان ،زيت القطن ،زيت الفول السوداني ،زيت الصويا ،زيت النخيل (وزيت الخروع المحلي )،والتي لها دورا مهما في صناعة الصابون وقدرت درجة التصبن عن طريق معايرة الأحماض الدهنية الحرة في وزنة قدرها (5 جرام )من الدهن أو زيت بواسطة معايرتها بحمض الهيدروكلوريك تركيزه (0.52N) وكذلك تم حساب رقم الأسترة ،واالرقم اليودي لكل العينات باستخدام محلول تركيزه0.1 عياري من ثايو سلفات الصوديوم Na2S2O3.5H2O والدليل المستخدم النشأ1%.
أأبوبكر ابراهيم أبوبكر الحاجي, فرج عبد الجليل العارف المودي, شعبان جاب الله سعيد الاسطى(3-2022)

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)

Abstract 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 underreported and inaccurate estimations 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 and subjected to microbiological enumeration and isolation techniques, followed by molecular identification by PCR and partial sequencing of 16S rDNA. Results: The results showed contamination of samples with enteric and spoilage bacteria. Fifteen genera of spoilage bacteria yielded 149 isolates which were detected and identified by PCR and partial 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 partial 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 qualities. These findings ought to be helpful in risk assessments and quality assurance of meat in order to improve food safety.
Hesham Taher Naas(9-2020)