-In this study, a new bacteriocin-producing strain Pediococcus pentosaceus BH105 was isolated from human faeces and subsequently in vitro probiotic and antagonistic properties were investigated. This strain exhibited high viability at pH 3.0 and in the presence of pepsin, pancreatin and bile salts (0.3%). BH105 was sensitive to 19 of 25 antibiotics and showed no haemolytic activity. The bacteriocin produced by BH105 was active at wide pH range of 2.0 to 11.0 and was heat stable at 80, 90 and 100 °C for 15 min. Bacteriocin activity was inhibited by pepsin, α-chymotrypsin, and proteinase K but not by trypsin, α-amylase, catalase, lysozyme and lipase. The Tricine-SDS-PAGE analysis allowed an approximation of bacteriocin BH105 size about 5 kDa. Pediococcus pentosaceus BH105 was able to adhere to Caco-2 cells (10.12 ± 2.40%) and inhibited the adhesion of Escherichia coli LMG3083 (88.72 ± 5.53%) and Salmonella typhimurium SL1344 (60.64 ± 10.97%).
Ezine cheese is a non-starter and long-ripened cheese produced in the Mount of
Ida region of Çanakkale, Turkey, with a protected designation of origin
status. Non-starter lactic acid bacteria (NSLAB) have a substantial effect on
the quality and final sensorial characteristics of long-ripened cheeses. The
dominance of NSLAB can be attributed to their high tolerance to the hostile
environment in cheese during ripening relative to many other microbial groups
and to its ability to inhibit undesired microorganisms. These qualities promote
the microbiological stability of long-ripened cheeses. In this study, 144
samples were collected from three dairies during the ripening period of Ezine
cheese. Physicochemical composition and NSLAB identification analyses were
performed using both conventional and molecular methods. According to the
results of a 16S rRNA gene sequence analysis, 13 different species belonging to
seven genera were identified. Enterococcus faecium
(38.42%) and E. faecalis (18.94%) were dominant
species during the cheese manufacturing process, surviving 12 months of ripening
together with Lactobacillus paracasei (13.68%) and
Lb. plantarum (11.05%). The results indicate that
NSLAB contributes to the microbiological stability of Ezine cheese over 12
months of ripening. The isolation of NSLAB with antimicrobial activity,
potential bacteriocin producers, yielded defined collections of natural NSLAB
isolates from Ezine cheese that can be used to generate specific starter
cultures for the production of Ezine cheese (PDO).
The probiotic characteristics of Lactobacillus brevis BG18 and Lb. plantarum BG33, isolated from traditional Turkish Tulum cheese were assessed. These two bacteriocinproducer strains exhibited good probiotic characteristics such as resistance in media containing 0.3% bile salt, pepsin (3 mg mL⁻¹), and pancreatine (1 mg mL⁻¹) as well as acid resistance at pH 2. They were also adhered to Caco-2 epithelial cells in a manner comparable to Escherichia coli LMG3083 (ETEC) and Salmonella Typhimurium SL1344. The strains produced a heat-stable antimicrobial compound that was shown to be proteinaceous in nature, and therefore, referred to as bacteriocins. The bacteriocins were able to inhibit growth of a number grampositive bacteria such as Listeria monocytogenes, Clostridium botulinum, Staphylococcus aureus and Bacillus cereus. Tricine-SDS-PAGE of the active fraction resulted in single bands with estimated molecular masses of 2.5 kDA and 2.7 kDA for Lb. brevis BG18 and Lb. plantarum BG33 bacteriocins, respectively.
Fermantasyon gıdaları bozulma etmeni ve hastalık yapıcı mikroorganizmalara karşı korumak için kullanılan en eski geleneksel yöntemdir. Termal uygulamalar, pH ve su aktivitesinin düşürülmesi ve koruyucu katkı maddelerinin ilavesi yaygın kullanılan diğer gıda muhafaza teknikleridir. Koruyucu katkı maddesi olarak çok sayıda antibiyotik ve kimyasal ajan geliştirilmiş olmasına rağmen, bakterilerin kullanılan antibiyotiklere karşı hızla direnç kazanmaları, kimyasal koruyucuların insan sağlığını tehdit edici boyutlarının bulunması ile çeşitli alerjik reaksiyonlara neden olmaları kullanımlarını sınırlayan faktörlerdir. Son yıllarda tüketicilerde gelişen mikrobiyolojik açıdan güvenli ve minimum işlem görmüş gıdalara karşı oluşan talep doğrultusunda toksik veya herhangi bir olumsuz etkisi bulunmayan, Laktik Asit Bakterileri gibi insan tüketimi için güvenli bakteriler tarafından üretilen bakteriyosinler üzerine yapılan çalışmalar yoğunluk kazanmıştır. Yeni nesil antimikrobiyel ajan olarak kabul edilen bakteriyosinlerin koruyucu olarak kullanılmasının gıdaların raf ömrünün uzatılması, kimyasal koruyucuların kullanımının ve bozulma etmeni mikroorganizmaların neden olduğu ekonomik kayıpların azaltılması gibi önemli etkileri bulunmaktadır. FDA tarafından GRAS (Genel Olarak Güvenli) olarak tanımlanan ve E234 koduyla 'Nisin-koruyucu' veya 'doğal koruyucu' olarak gıda katkı maddeleri listesinde yer alan Nisin, ilk olarak 1988 yılında ABD'de antibiyotiklerin gıdalarda kullanımının yasaklanmasıyla doğal koruyucu olarak kullanılmıştır. Nisinin günümüzde 50'den fazla ülkede süt ve ürünlerinden konserve gıdalara kadar pek çok gıdanın korunmasında başarılı uygulamaları bulunmaktadır.
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