مجله میکروبیولوژی کاربردی در صنایع غذایی
سال پنجم شماره 1 (بهار 1398)

This study evaluated the effects of different levels of probioenzyme™ (including four probiotic strains; Bacillus Lichenformis, B. subtilis, Entrococcus faecium, and Lactobacillus acidophilus with five enzymes α-glucanase, β-glucanase, α-xylanase, α-amilase, protease, and cellulase) on some growth performance, hematological indices and carcass proximate composition of grass carp fry. 120 fish (average weight of 7±0.5 g) were randomly divided into 12 fiberglass tanks. The fish were fed with three concentrations of probioenzyme including: 0 (control group), 1, 2 and 3 g/kg of feed for 45 days at 23.59±1.2 ºC. At the end of the trial, the hematological parameters were measured. The results showed that the use of probioenzyme increased the growth parameters and feed efficiency between treared groups compared to control one (p<0.05). The highest level of weight gain (10.02±0.22 g), specific growth rate (0.96±0.8 %/day), protein efficiency ratio (24.50±0.03) and condition factor (1.28±0.13 %) and the lowest level of feed conversation ratio (1.20±0.11) was observed in of 3 g of probioenzyme. Also, the level of WBC, monocyte and lymphocytes was not significantly difference between experimental treatments (p>0.05). However, the level of RBC, Ht and Hb were significantly increased in 3g probioenzyme compared with others (p<0.05). Also, the level of lipid and ash contents of the fish fleh showed not any significant differences between experimental treatment (p>0.05). While, the highest content of protein (14.33±29%) was observed in 3 g probioenzyme and the highest level of moisture (83.82±0.38%) was observed in 2 g probioenzyme per kg of feed (p<0.05). In conclusion, oral admistration of 3 g probioenzyme per kg of feed had a positive effect on growth performance, hematological indices and carcass quality of grass carp fry.

In this study, the chemical compositions, total phenolic content, antioxidant power and the antimicrobial effect of Heracleum lasiopetalum essential oil on Enterobacter aerogenes, Pseudomonas aeruginosa, Staphylococcus aureus, Listeria innocua and Candida albicans were determined. The essential oil was extracted by hydrodistillation. Its chemical composition was determined through gas chromatography-mass spectrometry in comparison with standard mass spectra. Total phenolic content and antioxidant activity were measured using the Folin-Ciocalteu and DPPH scavenging methods. The essential oil antimicrobial activity was quantified by disk diffusion, well diffusion agar, minimum inhibitory concentration and minimum bactericidal/fungicidal concentration methods. Eucalyptol was the major constituent of the essential oil with a percentage of 30.75. The total phenolic content and antioxidant power of the essential oil were 35/44±0.95 mg GAE/g and 24.20±1.60 mg/ml respectively. The antimicrobial activity based on disk diffusion and agar well showed that Candida albicans was the most sensitive species to the essential oil. The minimum inhibitory concentration of the essential oil was equal to 16, 16, 4, 8 and 4 mg/ml for Pseudomonas aeruginosa, Enterobacter aerogenes, Staphylococcus aureus, Listeria innocua and Candida albicans respectively. The results of the bactericidal and fungicidal concentrations were totally equal to or higher than those of the minimum inhibitory concentration. The results revealed that Heracleum Lasiopetalum essential oil has appropriate antioxidant power and is able to control the growth of foodborne pathogens and can be utilized as a natural preservative in food industry.

Citric acid is the most important organic acid that used in food industry and pharmaceutical industry. Todays, microbial methods are used to produce citric acid. It is mostly produced by microbial fermentation using Aspergillus niger. In this study we used Yarrowia lipolytica to biosynthesis of citric acid by solid state fermentation from different sources of carbohydrates, such as glucose and straw. At first the culture with different source of carbon were Prepared and yeasts were inoculated and incubated at 250c, 180 rpm for 5 days then concentration of citric acid were measured by spectrophotometer 420 nm. For optimized of conditions such as pH, temperature and, rpm we used Taguchi method. Result that shown that Yarrowia lipolytica could to biosynthesis of citric acid in glucose and straw. In glucose culture the best condition was 300c, pH=5.25, 180 rpm and the amount of citric acid produced was 0.819 g/L. In straw culture the best condition was 320c, pH=4.5, 200 rpm and the amount of citric acid produced was 0/959 g/L. Referring to the results Yarrowia lipolytica had a good potential to biosynthesis of citric acid, in other hands One of the aim of biotechnology, which is the use of agricultural waste and scrap material as a source of food for microorganisms, in this study provided.

Nowadays, the increase in diseases and the appearance of antibiotic-resistant bacteria has urged researchers to increase the nutritional health of society by applying new methods and benefiting from useful microorganisms, including probiotics. Therefore, the isolation and identification of beneficial microorganisms with probiotic properties has been important for increasing health among people. The most important probiotic bacteria are the genus Lactobacillus. In this study, Lactobacillus brevis strain PML1's probiotic properties have been evaluated. The tolerance of bile salts, antibiotic resistance, the ability to control pathogens, and the hydrophobicity properties of the strain have been studied. Then, in the complementary assay, the adhesion ability to Caco-2 cells, the survival in gastrointestinal simulated conditions are evaluated. The results show that the strain has a high potential for survival in bile salts of the intestine. The percentage of hydrophobicity of strain was 18/33%. Adhesion rates for Caco-2 cells were 13.8%, also L. brevis strain PML1 showed a high ability to prevent the pathogenicity of adhesion (35.5%). According to the results of the L. brevis strain PML1 has a relatively suitable probiotic potential. Therefore, it is recommended to use this strain as a probiotic supplement in fermentative cultivations or as a co-cultivation in the fermentation process of various foods.

Almond and soy milk, due to unsaturated fatty acids phytosterols and antioxidant Compounds are important among functional Drinks. Fermentation of these products using probiotic microorganisms of kefir grains increases the functional properties. Therefore, in this study, we investigated the physicochemical properties (acidity, antioxidant and viscosity), microbial (number of bacteria of lactic acid and yeast) and sensory of fermented almond / soybean milk using kefir starter. For this purpose, different conditions of fermentation processes including different concentrations of sugar (1-5%), and inoculum (0/04-0/1%), and fermentation temperature (20-30 °C) were investigated using response surface methodology (RSM) in Central Composite Design (CCD). The results showed by increasing the sugar concentration and inoculum, the acidity and antioxidant activity of the samples were increased. Effect of sugar concentration, inoculation and fermentation time had a significant effect on the number of lactic bacteria and yeasts (p<0.01). Sensory evaluation results of the samples showed that with increasing the percentage of inoculum, overall acceptance of samples were increased. Based on the results of the optimization of the conditions of the beverage production process, it can be stated that for the production of beverages with appropriate physico-chemical and organoleptic properties was 3.51% sugar concentration, 0.1% inoculation and 23.50 °C. fermentation temperature. In this condition, maximum antioxidation powerful, number of probiotics (acid lactic bacteria and yeasts), apparent viscosity was 47.19%, 48×106 cfu/ml and 28×106 cfu/ml, 165.17CP respectively with a maximum score for sensory assessments.

In the poultry industry, additives such as antibiotics are used to increase performance and reduce mortality. In recent years, probiotics are used in poultry nutrition due to their beneficial effects on production and absence in carcasses. In the poultry industry, Bacillus spp. probiotics are used to help increase feed intake and reduce the risk of salmonella infection. The purpose of this study was to isolate native probiotic strains with these abilities. In this research, 25 samples from freshly feces from 7 poultry and 16 samples from 3 rice field regions of Golestan province were collected. After isolation of Bacillus spp. on nutrient agar, their probiotic characteristics such as enzyme production, bile salt, acid, pepsin, trypsin and antibiotic resistance, and the ability of attachment to intestinal epithelial cells and inhibit Salmonella enterica serovar Typhimurium invasion were evaluated. The selected strain was identified by polymerase chain reaction (PCR) and 16S rDNA sequence. Top strain was identified as Bacillus tequilensis, which showed the highest binding to epithelial cells of the intestine and prevented the binding of Salmonella spp. This strain can improve the quality of poultry as a chicken diet and reduce the incidence of salmonellosis in chickens and humans, which, if this is achieved, will be a step towards consumer health. Considering the results obtained in this project, it is hoped to produce native probiotic for the prevention of Salmonella infection in Iran.