Sulfites and other preservatives are considered food additives to limit bacterial contamination, and are generally regarded as safe for consumption by governmental regulatory agencies at concentrations up to 5000 parts per million (ppm). Consumption of bactericidal and bacteriostatic drugs have been shown to damage beneficial bacteria in the human gut and this damage has been associated with several diseases. In the present study, bactericidal and bacteriostatic effects of two common food preservatives, sodium bisulfite and sodium sulfite, were tested on four known beneficial bacterial species common as probiotics and members of the human gut microbiota. Lactobacillus species casei, plantarum and rhamnosus, and Streptococcus thermophilus were grown under optimal environmental conditions to achieve early log phase at start of experiments. Bacterial cultures were challenged with sulfite concentrations ranging between 10 and 3780 ppm for six hours. To establish a control, a culture of each species was inoculated into media containing no sulfite preservative. By two hours of exposure, a substantial decrease (or no increase) of cell numbers (based on OD600 readings) were observed for all bacteria types, in concentrations of sulfites between 250–500 ppm, compared to cells in sulfite free media. Further testing using serial dilution and drop plates identified bactericidal effects in concentrations ranging between 1000–3780 ppm on all the Lactobacillus species by 4 hours of exposure and bactericidal effects on S. thermophilus in 2000ppm NaHSO3 after 6 hours of exposure.

No abstract

Qishta is a popular Middle Eastern coagulated cream product, prepared using a traditional heating and skimming process. This study in Lebanon aimed to assess the microbiological and chemical profile of the product. Samples selected from 31 different manufacturers and outlets were analysed using standard methods. The plate counts for the various microorganisms were either of borderline acceptability or unacceptable for Escherichia coli, Salmonella spp. and Listeria monocytogenes (detected in 32%, 7% and 42% of the analysed samples respectively). Chemically, the mean moisture content [67.5 (SD 2.6) g/100 g] and pH (6.53) were relatively high. High counts of spoilage and pathogenic microorganisms and the nature of its chemical composition make qishta highly perishable. ‫مالك‬‫أمل‬ ‫طوفييل،‬ ‫عامد‬ ‫نجار،‬ ‫حممد‬ ‫القصيفي،‬ ‫زينة‬ ‫الدراسة‬ ‫هذه‬ ‫وتسعى‬ ‫املعتادة.‬ ‫والقشد‬ ‫التسخني‬ ‫بعملية‬ ‫رَّ‬ ‫حتض‬ ‫وهي‬ ‫األوسط،‬ ‫الرشق‬ ‫يف‬ ‫الرائجة‬ ‫اللبن‬ ‫ختثر‬ ‫منتجات‬ ‫أحد‬ ‫هي‬ ‫القشدة‬ ‫إن‬ ‫اخلالصة:‬ ‫بالطرق‬ ‫العينات‬ ‫حتليل‬ ‫وجرى‬ ‫والبيع،‬ ‫للتصنيع‬ ً ‫خمتلفا‬ ً ‫موقعا‬ 31 ‫من‬ ‫عينات‬ ‫اختريت‬ ‫وقد‬ ‫املنتج.‬ ‫هلذا‬ ‫والكيميائي‬ ‫املكروبيولوجي‬ ‫املرتسم‬ ‫تقييم‬ ‫إىل‬ ‫اللبنانية‬ ‫دة‬ ِ ‫ح‬ ْ ‫َو‬ ‫ت‬ ْ ‫س‬ ُ ‫الـم‬ ‫واللستريية‬ ‫والساملونيلة،‬ ‫القولونية،‬ ‫لإلرشيكية‬ ‫بالنسبة‬ ‫يكاد‬ ‫أو‬ ‫مقبول‬ ‫غري‬ ‫اجلرثومية‬ ‫املزارع‬ ‫يف‬ ‫املختلفة‬ ‫املكروبات‬ ‫عدد‬ ‫وكان‬ ‫املعيارية.‬ ‫(بانحراف‬ 67.5[ ‫الرطوبة‬ ‫حمتوى‬ ‫متوسط‬ ‫كان‬ ‫فقد‬ ‫الكيميائية،‬ ‫الناحية‬ ‫من‬ ‫أما‬ ‫التـرتيب).‬ ‫عىل‬ ‫املفحوصة‬ ‫العينات‬ ‫من‬ ‫و24%‬ ‫و7%،‬ ،%32 ‫يف‬ ‫اكتشفت‬ ‫(إذ‬ ‫التـركيب‬ ‫وطبيعة‬ ‫للفساد،‬ ‫واملحدثة‬ ‫املمرضة‬ ‫املكروبات‬ ‫من‬ ‫الكبري‬ ‫العدد‬ ‫إن‬ . ً ‫نسبيا‬ ْ ‫ني‬ َ ‫مرتفع‬ )6.53( ‫والباهاء‬ ‫غرام]‬ ‫غرام/001‬ )2.6 ‫ه:‬ ُ ‫ر‬ ‫دْ‬ َ ‫ق‬ ‫معياري‬ ‫العطب.‬ ‫رسيعة‬ ‫جيعلها‬ ‫للقشدة‬ ‫الكيميائية‬ Profil microbiologique et chimique de la qishta libanaise (lait coagulé par traitement thermique)RÉSUMÉ La qishta est un produit crémeux coagulé très populaire au Moyen-Orient, préparé selon un procédé traditionnel de chauffage et d'écrémage. Cette étude réalisée au Liban visait à évaluer le profil microbiologique et chimique de ce produit. Les échantillons choisis auprès de 31 fabricants et points de ventes ont été analysés à l'aide de méthodes standardisées. Le comptage sur plaque des divers micro-organismes a fourni des valeurs soit à la limite de l'acceptabilité, soit non acceptables pour Escherichia coli, Salmonella spp. et Listeria monocytogenes (détectées dans 32 %, 7 % et 42 % des échantillons analysés, respectivement). Sur le plan chimique, la teneur moyenne en eau (67,5 g/100g [ET 2,6]) et le pH (6,53) sont apparus relativement élevés. Compte tenu du nombre important de micro-organismes pathogènes et provoquant l'autolyse qu'elle contient et de la nature de sa composition chimique, la qishta est une denrée très périssable.

Aims: This study aims to predict the presence of bacteriocin-and probiotic-associated genes in the genome of Weissella cibaria NM1 isolated from Asian sea bass using a machine learning-based NeuBI prediction approach, followed by the investigation of the crude bacteriocin antimicrobial and probiotic properties via in vitro analysis. Methodology and results: This study utilized the machine learning-based NeuBI prediction approach with a homology search of highly conserved bacteriocin-associated genes present in the genome of W. cibaria NM1. This approach discovered a putative bacteriocin gene (WC_2064) and bacteriocin operon with complete immunity, transporter, regulator and modifier genes. Furthermore, the genome of W. cibaria NM1 was found to harboured specific probioticassociated genes that would contribute to acid and bile tolerance, adhesion on the host cell and exhibited cholesterolreducing ability. On top of that, the genome also shows the absence of virulence and antibiotic resistance genes, which signifies the safety of W. cibaria NM1 as a potential probiotic candidate. In vitro study has confirmed the antipseudomonal activity of crude bacteriocin NM1 with MIC of 62.5 mg/mL. Weissella cibaria NM1 can tolerate 0.3% (v/v) of bile salt condition and the transit through the simulated gastric (pH 3 and 4) and small intestinal (pH 8) tract. Conclusion, significance and impact of study: Current findings suggested in silico approach can speed up the search for putative bacteriocin and probiotic-associated genes from the genome of W. cibaria NM1. Nevertheless, further verification through experimental works will be deemed essential.