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One of the important factors which affect lactic starter cultures activity as well as lack of lactic coagulation in milk is antibiotic residues. Lack of lactic coagulation causes a number of problems such as economic loss in dairy industries when they produce fermented milk products specially cheese and yoghurt. In order to recognize such problem, the present study was undertaken to detect antibiotic residues in milk. The results obtain showed, cow milk which contaminated by ointment in a concentration about 100ppm and the cow under treatment by streptomycin (intramuscular injection) up to 72 hours after injection, no lactic coagulation was observed. Hence, the cow under treatment should be kept separate and the milk drawn should never be mixed with other animals until the antibiotic residues reduce to normal range. Above mentioned parameter have different affects on enzymatic coagulation of milk .

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The present study was conducted to evaluate the effect of Lactobacillus plantarum (KC426951) isolated from the intestine of rainbow trout Guilan on growth factors, carcass composition and the intestinal bacterial flora of rainbow trout (Oncorhynchus mykiss) was conducted. Rainbow trout weighing 3.56±2.24 for 2 weeks were consistent with environmental rearing conditions. Five groups of fish were fed with diets containing 10⁶ (T1), 10⁷ (T2), 10⁸ (T3), 10⁹ (T4), 10¹⁰ (T5) cfu g^-1 of L. plantarum and control group (T6) without diet containing probiotics were fed for 60 days. Results showed that final weight, final length, growth rate, percent weight were gained in treatment 2 the highest and 5 the lowest level in treated. Also, FCR lowest rates in treatment 2 and treatment 5 were accounted for most (p<0.05). The highest total count of lactic acid bacteria were obtained in the intestine of T4(p<0.05). Maximum carcass protein was observed in T4, and low fat content is related to the control treatment (p<0.05). According to the results obtained from the use of Lactobacillus plantarum could be considered as a positive factor for the improvement of the intestinal bacterial flora, growth performance and carcass composition could be used.  

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4 lactobacillus plantarum, strains isolated from natural olive fermentation, was used as a starter culture for aerated olive (Manzanilla green olive) fermentation. Lactic acid bacteria are essential microorganisms in green olive fermentation. Inoculation with a starter culture of lactobacillus plantaru 5 – 7days after brining could standardize olive proccessing. This lactobacillus plantarum must isolated from olive fermentation that is tolerated to high levels of lactic and acetic acids and high level Nacl concentration and also oleuropein 1%. Fermentation took place in 4 glass baril (15 L) with 7 kg of olives and 7 L of brine. Baril 1,baril 2  that were treated with 8% salt and 0.1% acetic acid. Baril 3,baril 4  that were treated with 6% salt and 0.3% acetic acid. Inoculation took place in 5 days after brining for baril 2,4. Aerated condition for barils were supplied with aeration column for approximately 190 days and incubated in 28°C. The samples (olives and brines) were taken at different  fermentation phases. Physical and chemical analyses of olive during the fermentation were including salt, protein, fat, acidity, moisture,ash and in brine olive were including acidity, salt, reducing sugar, pH. In this research, the use of suitable lactobacillus plantarum starter cultures has the potential to improve the microbiological control of process, increase the lactic acid yield and, accordingly, increasing acidity in brine olive and provide the production of natural fermented green olives of consistently high quality. Thus use of inoculation lactic acid bacteria can applied as a new technology during the olive fermentation.

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The aim of this study was to develop a biopreservation strategy for cold-smoked Caspian  roach by the use of Lactobacillus casei previously selected for their capability to inhibit the growth of Listeria monocytogenes in this product.  An application on commercial smoked Caspian roach was tested by spraying L. casei (10⁴ CFU g^-1) on slices smoked Caspian roach. Microbial and chemical characteristics were each ten days compared to a control during forty days of storage. No significant differences were showed in microbiological and chemical characteristics of  inoculated slices with  L. casei. The strain L. casei  inoculated in SCR in a biopreservation goal exhibits some interesting properties: it is able to grow at high level without giving major quality changes in the product. In conclusion, biopreservation of SCR using lactic acid bacteria such as L. casei is a promising way to inhibit the growth of pathogenic bacteria such as L. monocytogenes with low effect on the quality of the product.

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Milk, curd, fresh (1-day old) and ripened (90-days old) Lighvan cheese (10 samples from each one) have been investigated for lactic flora as one the most well-known starter free sheep raw milk cheeses. MRS, MRS+vancomycin, M17 and KAA media were used for determining of Lactobacilli and Pediococci, Leuconostocs, Lactoccoci and Enterococci genera, respectively. Isolated strains were identified up to genus level with gram staining and catalase test, morphology, colony pigmentation,gas production from glucose,growth in 10°C and 45°C,salt tolerance,growth at pH9.6, argenine hydrolysis and citrate utilization. Random colonies were selected from each medium and confirmatory tests showed Enterococcus (33.68%), Lactobacillus (33.68%) and Lactococcus (26.31%) as the most common genera during the all stages. Finally, these isolated colonies were subjected to carbohydrate fermentation with API 50 CH and API 20 STREP methods and were determined up to species and sub species level. Totally,95 strains were isolated and identified during all production stages. API system results showed the following species: Lactobacillus plantarum, Lb. brevis, Lb. paracasei ssp. paracasei, Lb. delbrueckii ssp. delbreuckii, Lb. fructivorans, Lac. lactis. ssp. lactis, Enterococcus.faecalis, Ent. faecium, Ent. durans, P. pentosaceus, Leu. lactis, Leu. mesenteroides. The lactic acid bacteria changes revealed the pattern that Lactococcus and Lactobacillus were predominant at the first stages and replaced by Enterococcus at the end of production and ripening stage.The most dominant species during all satages follows as: Lac. Lactis ssp. lactis (25.26%), Lb. plantarum (20%), Ent. Faecalis (15.78%), Ent. faecium (15.78%). Thus, we expect that these species may play an important role in ripening and production of Lighvan cheese and also have potential application in industrial scale.  

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Fermented sausage is a favorite kind of meat-product that has allocated great proportions meat consumption in the world to itself. For the first time in Iran in this study, production of Fermented sausage from muscle tissue of common carp (Cyprinus carpio) was assessed by means of lactic acid bacteria at different incubation temperatures as 15, 25, 35 ˚C To prepare the fish sausage, common carp mince was grounded and mixed with NaCl (3%), glucose (3%) and lactic acid bacteria (5 log CFU/g) and incubated for 48 h. During the incubation of fish sausage, pH, microbiological tests, moisture and protein content, and TVB-N were measured. According to the results, higher temperature stimulated the rapid growth of lactic acid bacteria, resulting in a rapid decline in pH, and consequently suppressed the growth of pseudomonas, Micrococcaceae and Enterobacteriacea. Finally, apart from the TVB-N parameter, the fish sausage in which was fermented at 35 °C showed better results in terms of pH and bacterial load compared to the other incubation temperatures.    

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  The aim of this work was identified lactic floraas a traditional fermented food and then evaluates antimicrobial activities of some strains. A total of 140 Gram-positive and catalase-negative isolates were subjected to grouping by physiological and biochemical tests and carbohydrates fermentation. Based on the resultsthese 140 isolateswere dividedinto 9 groups. Two or three isolated were selected from each group and 16S rRNA was amplified using universal primers. Diversity of lactic acid bacteria in horreh was as followings:Lactobacillus fermentum (30.00%),Lactobacillus plantarum (28.57%), Lactobacillus brevis (15.00%), Weissellacibaria(8.57%),Enterococcus (faecium and faecalis) (7.14 %), Leuconostoc (citreumand mesenteroides subsp.Mesenteroides) (6.42%) and Pediococcus pentosaceus (4.28%). Antagonistic activity of 20 isolates (strains) of lactic acid bacteriaobtained fromhorreh was evaluated against food- borne bacteria. Sixteen isolates in Agar spot method and 14 isolates in well diffusion assayshowed antibacterial activity against at least one of these indicators. Eight isolates including:Ent. faecium (1), Ent. faecalis (1), P. pentosaceus(1) and Lb. plantarum (2) exhibited  the  highest  antagonistic  activity toward Listeria innocoa. Antagonistic activity of cell free supernatant (CFS) from Lb. plantarum showed the highest thermal stability. Also, two isolates belonging to:Ent. faecium, Ent. Faecalis presented antibacterial activity at pH=7. Only, the supernatant of Lb. plantarum was not influenced by proteinase K.The results showed that the supernatant of some isolatestestedcan be used as a bio preservative in food products.

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     In this study, antimicrobial activity of lactic acid bacteria isolated from traditional Kurdish cheese was evaluated. At first, cell free culture supernatant was prepared, and then divided into three groups (control, treated by heat and treated by NaOH). Antimicrobial activity of supernatant treated or no treated was investigated utilizing Agar diffusion, Disk diffusion and Minimum Inhibition Concentration. In addition, coaggregation of lactic acid bacteria against pathogens was determined. Results showed native lactic acid bacteria were suitable antimicrobial activity in comparison to commercial lactic acid bacteria. Heating of supernatant hadn’t effect on antimicrobial activity, while treating by NaOH didn’t show antimicrobial activity. In addition, native lactic acid bacteria didn’t show significant difference in minimum inhibition concentration with commercial lactic acid bacteria. Native lactic acid bacteria also have a suitable coaggregation with pathogens. Results of this study showed native lactic acid bacteria isolated from traditional Kurdish cheese can be used as natural antimicrobial agents.

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Fruits, vegetable and juices are always interested due to their nutritional contents such as vitamins, minerals and antioxidants. They also seemed to be a suitable media culture for lactic acid bacteria growth and lactic fermentation. In this research, production of a functional beverage red beet juice and fermenting in 37ºC by lactic acid bacteria was carried out. Bacterial growth kinetics, sugar consumption, Acid production and changes in antioxidant activity have been investigated. Lactobacillus reuterii were found to grow faster and produced higher amount of viable cells during fermentation followed by L. delbruckii, L. acidophilus, L. casei, L. paracasei, L. rhamnosus, L. plantarum and L. helveticus. Reducing sugars including sucrose, fructose and glucose were consumed by L. casei and L. delbruckii were more intended to use lactose. Lactic acid was the predominant produced lactic acid which was manufactured by L. reuterii. Antioxidant activity and total polyphenolic compounds increased significantly fermentation and maximum reduction in EC50 has been observed in fermentation by L. rhamnosus and, L. acidophilus in anti-oxidant activity and L. casei,L. rhamnosus and L. helveticus in total polyphenolic compounds. Finally, L. casei was found to growing well in this beverage, resulted in producing functional fermented beverage.

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Doogh is a traditional Iranian fermented milk drink, which is produced by lactic fermentation of pasteurized milk. In order to isolate and identify the microorganisms present in Iran industrial Doogh samples, polymerase chain reaction (PCR) was applied. Doogh samples were 17 name brands. After conducting the preliminary identification by microscopic observations and biochemical tests, in order to verify the obtained results the samples were pure-cultured which was followed by PCR and sequencing. According to the results obtained through sequencing of 16S rRNA, the identified bacteria belonged to lactic acid bacteria (Lactobacillus brevis, L. fermentum, L. paracaseiand L. gallinarum); gram-posetive spore-forming bacteria (Bacilluslicheniformis, B. anthracis and B. subtilis) and acetic acid bacteria (Acetobacter tropicalis and A. indonesiensis). Moreover, based on the results obtained by sequencing of D1/D2 26S rDNA the identified yeasts were including Pichia fermentans, Saccaromyces unisporous and Cryptococcus magnus. The obtaining of present study illustrated that in addition to identified non-starter lactic acid bacteria, other types of bacteria and yeasts were found in Iran industrial Doogh samples.

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Fermentation is used for centuries to protect quality improvements or flavor modifications of cereals, fruits, vegetables, milk and meat. Yellow Zabol kashk (Sistani) is a grain-dairy fermented product, which is highly consumed in Sistan-Baluchistan province. The aim of this study was to isolate and identify the Lactic Acid Bacteria involved in spontaneous fermentation of this product to introduce the native strains. These strains could be used in industry or some of them may be considered as probiotic strains. The cell morphology of each strain was investigated. Then gram-positive and catalase-negative isolates were selected. In order to classify 83 selected isolates that seemed Lactic Acid Bacteria according to preliminary experiments, physiological and biochemical tests, including growth at 10°C and 45°C, 6.5%  NaCl, pH=4.4 and pH=9.6, carbon dioxide production from Glucose and carbohydrates fermentation were performed. Twenty eight selected isolate identified genotypically based on 16S rRNA gene sequencing. The results showed that the isolates belong to: Lactobacillus plantarum (24.09 %), Lactobacillus helveticus (13.25 %), Lactobacillus brevis (963 %), Lactobacillus delbrueckii (18.07 %), Lactococcus lactis (13.25 %), Leuconostoc mesenteroides (9.63 %), Leuconostoc citreum (2.40 %) and Pediococcus pentosaceus (9.63 %). To identify the bacteria, especially lactic acid bacteria it is suggested using both culture and molecular-based method.

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Dairy products can be a rich source of diverse lactic acid bacteria (LAB) with high functional properties, such as exopolysaccharide (EPS) production. EPS are high molecular weight polymers that are composed of sugar units and are secreted by microorganisms into the surrounding environment. Produced EPS can be used as an additive by a health effect and texture properties. In this study, exopolysaccharide producing LAB (ropy and mucoid colonies) were isolated and identified from raw sheep milk and sheep yogurt that made in rural areas of Urmia. For this purpose, lactic acid bacteria cultured on MRS agar and M17 agar media and then isolated on the basis of the ability to produce exopolysaccharides to study the diversity of species by phenotypic methods (Gram stain, biochemical and physiological tests) and then identified by polymerase chain reaction (PCR). 7 strains of LAB isolated were Gram-positive as well as catalase negative and were able to produce large amounts of EPS. The amounts of bonded and abandoned exopolysaccharides which measured by phenol/sulfuric acid method were 40.28±0.2 to 65.26±0.47 mg/L and 105.68±3.2 to 136.35±0.2 mg/L, respectively. Sheep yogurt which manufactured traditionally in West Azerbaijan province contained exopolysaccharide-producing strains that can have the potential to use in the dairy industry.

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Lactic acid bacteria (LAB) are widely used in the food industry as starter cultures for fermentation. Bacteriocin is one of the most important natural inhibitory substances which is produced by various starins such as L.plantarum, the most known member of LABs. In this study, some characters of produced bacteriocins by two isolates of L.plantarum were studied. At fiest, two native isolates of L.plantarum BL1 and L.plantarum EL3 were selected from microbial collection of ABRII, and then the antibacterial trait and inhibitory spectrum of produced bacteriocins were determined. Therefore, bacteriocidal or bacteriostatic activity of produced bacteriocins, and thermal stability of them in different tempretures were studied. Molecular weight of bacteriocins were estimated by SDS-PAGE technique. According to achieved results, produced bacteriocins by two isolates were active against all used pathogens Also, it was observed that both produced bacteriocins were sensitive to proteinase-K. In contrast, alpha-chymotrypsin was not able to destroy bacteriocins properly. Both bacteriocins were resistant to thermal treatments. Produced bacteriocins by both studied L.plantarum strains, had molecular weight lower than 10 kDa and taked place in specified range of class IIb bacteriocins.

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Some lactic acid bacteria (LAB), in particular proteolytic strains, in raw milk have useful technological properties and play important role in developing desired characteristics in the final products. However, they are mostly lost during heating and technological processes. Therefore, it would be important to be isolated and maintained for further applications as pure adjunct cultures. In this study, after selective isolation of LAB from raw cow’s, ewe’s and goat’s milks on MRS agar and M17 agar, Gram-positive catalase-negative were selected and maintained as pure cultures. Then, the isolates were screened according to their proteolytic activities on skim milk agar (well-diffusion method). The potent Gram-positive, catalase-negative proteolytic strains were identified via 16S rDNA gene sequencing and antibiotic resistance (10 antibiotic agents, disc-diffusion method) and hemolytic activities (on blood agar containing 5% sheep blood) were evaluated. BLAST analysis resulted in identification of Lactobacillus delbruekii (five isolates), L. delbruekii subsp. bulgaricus, L. fermentum, L. reuteri, L. curvatus, Lactococcus lactis subsp. Lactis, and Streptococcus lutetiensis. L. lactis subsp. Lactis obtained from cow milk showed the highest proteolytic activity as a 23-mm halo zone was observed on skim milk agar plate after 48 h incubation at 37 °C. In case of hemolysin production, only Lactobacillus fermentum showed α-hemolytic activity and the others showed no activities. All the identified isolates were sensitive to tetracycline, ampicillin, erythromycin, vancomycin and gentamycin with the exception of L. reuteri and lactococcus lactis subsp. lactis that found to be resistant to vancomycin and gentamycin, respectively. About penicillin, chloramphenicol, clindamycin, kanamycin and gent streptomycin, the results were varied. Our results verified diversity of wild proteolytic LAB strains in raw milk, as reported before. Although LAB mainly belong to the GRAS list, strains isolated from raw milk should be re-checked for their safety-related properties.

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Fungal spoilage plays an essential role in the deterioration of food and in the creation of foodborne disease. In addition, the production of various mycotoxins by fungi can cause serious dangers such as carcinogenic, teratogenic, immunotoxic, neuromastoxic, toxic dead, mycotoxicosis and Kashin Beck disease. On the other hand, despite the increasing resistance of molds to synthetic preservatives, that may produce carcinogenic nitrosamine, no effective strategy has been proposed to safely reduce of microbial growth for public health. Therefore, due to the safe and probiotic properties of the lactic acid bacteria that have been approved (GRAS and QPS), can be used as natural preservatives to prevent fungal spoilage of food. The ability to prevent and inhibitory fungal spoilage by lactic acid bacteria is mainly due to the production of antimicrobial compounds such as organic acids, fatty acids, hydrogen peroxide, phenyllactic acid, cyclic delpeptide, proteinaceous compounds, diacetyl, bacteriocin and reuterin. Also, the most important inhibitory mechanisms of lactic acid bacteria against fungal corruption include membrane  destabilization, proton  gradient interference,  enzyme  inhibition,  and  creation  of  reactive  oxygen  species. Therefore, in this paper, it has been tried to overview of antifungal metabolites and their chemical structure, inhibitory mechanisms and probiotic properties of the lactic acid bacteria.

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Masske butter or butter derived from yogurt is a traditional butter used in southern Khorasan with a wide range of lactic bacteria. The aim of this study was to investigate the antibacterial effect of lactate isolates against of Staphylococcus aureus and Salmonella enterica. In this research, lactic isolates were first detected by PCR method, and then microdilution method was used to evaluate the antimicrobial activity of the isolates. BLAST of sequences of S16 rDNA gene with sequences stored in the NCBI database led to the identification of the genus Lactobacillus bulgaricus, Enterococcus faecium, Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus delbrueckii and Enterococcus hirae. The results of antimicrobial activity evaluation against Staphylococcus aureus and Salmonella enterica bacteria showed that all isolates were able to inhibit the growth of these two pathogens, and their inhibitory percent from 55/46 to 84/49 and from 55/46 to 56/55 respectively was variables. Also, the results showed that Lactobacillus plantarum B38, Enterococcus hierae B224, Lactobacillus delbrueckii B37 had the highest inhibitory effect against Staphylococcus aureus (P>0.05) and Lactobacillus plantarum B38 showed the highest percentage of inhibition against Salmonella enterica (P<0.05). In addition, it was found that the inhibitory effect of all isolates against Staphylococcus aureus was significantly higher than Salmonella enterica (P< 0.05). Therefore, lactic acid bacteria isolated from the Masske butter can be used to control the food borne pathogens and food spoilage microorganisms.
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The application of probiotic starter cultures in fermented products is expanding in different communities. The genetic variation makes the effects of these bacteria different and unpredictable in different human societies. Therefore, the safety control and evaluation of their non-pathogenicity is of great importance and monitoring centers are required to closely monitor the safety of the bacteria used in food products.
In this study, two strains of Lactobacillus isolated from dairy products of Ardabil (Heyran mountain road villages) and Khuzestan province (Behbahan city) in Iran were identified based on the biochemical and molecular properties through sequence analysis of 16S rRNA gene. Then, their safety was examined based on the international guidelines, especially the European :union: standard. The two identified strains included Lactobacillus fermentum (PTCC 1929) and Lactobacillus helveticus (PTCC 1930). The results showed the lack of gelatinase enzyme, inability of blood hemolysis, inability of amino acids decarboxylation and the lack of genes responsible for the invasive characteristics of pathogenic microorganisms including gelE, efaA_fm , efaA_{fs ,} agg, ace, cylM, cylA, cylB.  In addition, the results showed the sensitivity of both isolates to Penicillin, Ampicillin, Rifampicin and Tetracycline, and their resistance to Kanamycin and Ciprofloxacin. Lactobacillus fermentum was resistant to vancomycin, whereas Lactobacillus helveticus was susceptible to it. Since cases of antibiotic resistance are inherent according to scientific reports, the obtained results confirmed the potential application of these two isolated strains as starter in the fermented dairy products. It also confirmed the necessity of using safety assessment procedures for probiotic bacteria.

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Aflatoxins are potent carcinogenic and immunosuppressive agents. Acute exposure to high level of aflatoxins leads to aflatoxicosis, which cause rapid death due to liver failure. Immune modulating effects of probiotic bacteria have good prospects to detoxification of natural foods. This study was aimed to investigate the ability of Lactobacillus acidophilus strainLA-5 in the presence and absence of yoghurt starter culture for removing Aflatoxin M₁ (AFM₁) in comparison with yoghurt starter cultures (10⁸ CFU ml^-1). AFM₁ detoxification was evaluated for 21 days of yoghurt storage at 4°C at different concentrations of Aflatoxin (0.1, 0.5 and 0.75 µg L^-1). The amounts of unbound AFM₁ were determined using competitive Enzyme-Linked Immunosorbent Assay (ELISA). L. acidophilus combined with yoghurt starter culture and alone could significantly (P≤ 0.05) remove AFM₁ compared to control group. The results indicated that increasing initial AFM₁ concentration in the yoghurt samples and storage time affected the capacity of AFM₁ binding.