Isolation and characterization of two Staphylococcus aureus lytic bacteriophages "Huma" and "Simurgh".

Nowadays finding the new antimicrobials is necessary due to the emerging of multidrug resistant strains. The present study aimed to isolate and characterize bacteriophages against S. aureus. Strains Huma and Simurgh were the two podovirus morphology phages which isolated and then characterized. Huma and Simurgh had a genome size of 16,853 and 17,245 bp, respectively and both were Rosenblumvirus with G + C content of 29%. No lysogeny-related genes, nor virulence genes were identified in their genomes. They were lytic only against two out of four S. aureus strains. They also were able to inhibit S. aureus for 8 h in-vitro. Both showed a rapid adsorption. Huma and Simurgh had the latent period of 80 and 60 m and the burst sizes of 45 and 40 PFU/ml and also, they showed very low cell toxicity of 1.23%-1.79% on HT-29 cells, respectively. Thus, they can be considered potential candidates for biocontrol applications.

A mechanistic simulation of induced DNA damage in a bacterial cell by X- and gamma rays: a parameter study.

Mechanistic Monte Carlo simulations calculating DNA damage caused by ionizing radiation are highly dependent on the simulation parameters. In the present study, using the Geant4-DNA toolkit, the impact of different parameters on DNA damage induced in a bacterial cell by X- and gamma-ray irradiation was investigated. Three geometry configurations, including the simple (without DNA details), the random (a random multiplication of identical DNA segments), and the fractal (a regular replication of DNA segments using fractal Hilbert curves), were simulated. Also, three physics constructors implemented in Geant4-DNA, i.e., G4EmDNAPhysics_option2, G4EmDNAPhysics_option4, and G4EmDNAPhysics_option6, with two energy thresholds of 17.5 eV and 5-37.5 eV were compared for direct DNA damage calculations. Finally, a previously developed mathematical model of cell repair called MEDRAS (Mechanistic DNA Repair and Survival) was employed to compare the impact of physics constructors on the cell survival curve. The simple geometry leads to undesirable results compared to the random and fractal ones, highlighting the importance of simulating complex DNA structures in mechanistic simulation studies. Under the same conditions, the DNA damage calculated in the fractal geometry was more consistent with the experimental data. All physics constructors can be used alternatively with the fractal geometry, provided that an energy threshold of 17.5 eV is considered for recording direct DNA damage. All physics constructors represent a similar behavior in generating cell survival curves, although the slopes of the curves are different. Since the inverse of the slope of a bacterial cell survival curve (i.e., the D10-value) is highly sensitive to the simulation parameters, it is not logical to determine an optimal set of parameters for calculating the D10-value by Monte Carlo simulation.

Effects of Partial Replacement of Sugar with Fig Syrup on the Survival of Bacillus coagulans and the Physicochemical Properties of Probiotic Ice Cream.

Research background: Various sectors of the food industry demand the enrichment of food with functional compounds. Probiotic products with valuable nutritional and therapeutic properties have attracted great attention in the fields of industry, nutrition and medicine. The aim of the present study is to investigate the sensory and physicochemical properties of probiotic ice cream containing fig syrup and to evaluate the survival of Bacillus coagulans after 90 days of storage at -18 °C. Experimental approach: In this study, four experimental groups of ice cream were produced as follows: plain dairy ice cream (without additives), ice cream containing 109 CFU/g B. coagulans, ice cream containing 25 % fig syrup as sugar substitute and ice cream containing 25 % fig syrup as sugar substitute and 109 CFU/g B. coagulans. They were stored at -18 °C for 3 months. Texture, pH, acidity and viscosity were analysed and microbial counts were determined after 1, 30, 60 and 90 days of storage. The organoleptic evaluation was carried out on days 1 and 90. Results and conclusions: The results showed that during the initial freezing process and the transformation of the mixture into ice cream, the number of B. coagulans decreased from 109 to 107 CFU/g, without significant changes observed over the 90-day period. No significant changes were found in the sensory and textural properties of the samples either. Replacement of 25 % sugar with fig syrup reduced the pH, increased the acidity of the ice cream and improved their viscosity. In conclusion, the production of functional ice cream using fig syrup and B. coagulans is recommended for their health benefits. Novelty and scientific contribution: The results of this study can be used to prepare functional and healthy foods. Our results suggest that fig syrup has the potential to be used as a natural sweetener or sugar substitute in various products.

Isolation and molecular characterization of the Salmonella Typhimurium orphan phage Arash.

The current threat of multidrug resistant strains necessitates development of alternatives to antibiotics such as bacteriophages. This study describes the isolation and characterization of a novel Salmonella Typhimurium phage 'Arash' from hospital wastewater in Leuven, Belgium. Arash has a myovirus morphology with a 95 nm capsid and a 140 nm tail. The host range of Arash is restricted to its isolation host. Approximately 86% of the phage particles are adsorbed to a host cell within 10 min. Arash has latent period of 65 min and burst size of 425 PFU/cell. Arash has a dsDNA genome of 180,819 bp with GC content of 53.02% with no similarities to any characterized phages, suggesting Arash as a novel species in the novel 'Arashvirus' genus. Arash carries no apparent lysogeny-, antibiotic resistance- nor virulence-related genes. Proteome analysis revealed 116 proteins as part of the mature phage particles of which 27 could be assigned a function. Therefore, the present findings shed light on the morphological, microbiological and genomic characteristics of Arash and suggest its potential application as therapeutic and/or biocontrol agent.

The beneficial effects of spraying of probiotic Bacillus and Lactobacillus bacteria on broiler chickens experimentally infected with avian influenza virus H9N2.

This study investigated the clinical, antiviral, and immunological effects of spraying Bacillus spp. and Lactobacillus spp. as a single or mixture probiotic compound on experimentally infected broiler chickens with AIV H9N2. Two hundred and forty 1-day-old broilers were randomly assigned to 6 groups as follows: Ctrl- (no challenge AIV; no spray probiotic), Ctrl+ (AIV challenged; no spray probiotic), AI+B (AIV challenged; daily spraying of probiotic Bacillus spp.), AI+L group (AIV challenged; daily spraying of probiotic Lactobacillus spp.), AIV+BL (AIV challenged; daily spraying of probiotic Bacillus spp. and Lactobacillus spp.), and G-DW (daily spraying of normal saline; no AIV challenged). The birds were reared for 35 d. On the 22nd day of age, broiler chickens were challenged by AIV H9N2. The probiotics were sprayed at 9×109 CFU/m2 daily for 35 d. Growth performance, clinical signs, virus shedding, macroscopic and microscopic lesions were evaluated at various days in all groups. Spraying with probiotics improved the body weight gain and food conversion ratio in the AI+B, AI+L, and AI+BL groups compared to the Ctrl+. The severity of clinical signs, gross lesions, pathological lesions and viral shedding in the probiotic treatment groups was lower than in the Ctrl+ group. The findings of this study suggest the daily spraying of Lactobacillus and Bacillus probiotics alone or in combination during the rearing period reduce clinical and nonclinical aspects of H9N2 virus infection; so, it can be effective as a preventive protocol for controlling the severity of AIV H9N2 infection in broilers.

Expression, purification and investigation of antibacterial activity of a novel hybrid peptide LL37/hBD-129 by applied comprehensive computational and experimental approaches.

Antibiotic-resistant pathogens have become a great universal health concern. Antimicrobial peptides (AMPs) are small amphipathic and cationic polypeptides with high therapeutic potential against various microorganisms containing drug-resistant strains. Two major groups of these peptides, which have antibacterial activity against Gram-positive and Gram-negative bacteria, antiviral activity, and even antifungal activity, are defensins and cathelicidins. Hybridization of various AMPs is an appropriate approach to achieving new fusion AMPs with high antibacterial activity but low cellular toxicity. In the current research, the amino-acid sequence of human cathelicidin LL-37 (2-31) and Human beta-defensin (hBD)-129 were combined, and the fusion protein was evaluated by bioinformatics tool. The designed AMP gene sequence was commercially synthesized and cloned in the pET-28a expression vector. The LL-37/hBD-129 fusion protein was expressed in E.coli BL21-gold (DE3). The expression of the recombinant protein was evaluated using the SDS-PAGE method. The LL37/hBD-129 was successfully expressed as a recombinant hybrid AMP in E.coli BL21-gold (DE3) strain. Purification of the expressed AMP was performed by Ni-NTA column affinity chromatography, and the purified AMP was validated using the Western blot technic. Finally, the antimicrobial activity of the fusion AMP against Staphylococcus aureus and Escherichia coli bacteria was assessed. Based on the in silico analysis and experimental evaluations, the fusion AMP showed a significant antimicrobial effect on E. coli and Staphylococcus aureus bacteria.

Prevalence and risk factors associated with Q fever infection in slaughterhouse workers in Fars province, Iran.

OBJECTIVE: Q fever is a main occupational zoonotic disease. Slaughterhouse is one of the most remarkable ways of transmitting the infection from livestock to humans. This study aimed to survey the prevalence of Q fever in slaughterhouse workers in Fars province, Iran, for the first time. METHODS: Ninety serum samples were collected from slaughterhouse workers and tested to detect Immunoglobulin G (IgG) against Coxiella burnetii using ELISA and indirect immunofluorescence assay (IFA). PCR was also applied to identify C. burnetii DNA in the blood samples. RESULTS: Q fever seroprevalence was found at 26.7% in ELISA, showing recent infection. This result indicates that Q fever seroprevalence is relatively high in the Fars region. IFA showed a high seroprevalence of total IgG antibodies at 1:64 titer (73.3%) and relatively high IgG at 1:256 titer (40%) against C. burnetii. 2.2% of the workers were recognized as having probable acute Q fever. The IgG II prevalence at 1:64 and 1:256 titers was, respectively, 63.3% and 24.4% positive. The IgG I prevalence at 1:64 and 1:256 titers was also found 33.3% and 22.2% positive, respectively. Molecular prevalence of Q fever was also 8.9%. A significant relationship was found between IgG I seropositivity and longer work experience and employing other livestock-related jobs (animal husbandry and butchery) (P < 0.05). CONCLUSIONS: As such, the high seroprevalence of Q fever among abattoir workers highlights the importance of further comprehensive epidemiological studies, occupational screening programs, and preventive measures for Q fever in high-risk groups. This also warns animal health care organizations about the risk of Q fever infection in livestock in this region.

Microencapsulation of Lacticaseibacillus rhamnosus GG and L. plantarum 299 V by reverse spherification: a promising method to improve the survival of probiotics.

This research reports the first application of the reverse spherification (RVS) method for encapsulation of two probiotics (Lacticaseibacillus rhamnosus GG and L. plantarum 299 V) compared to the basic spherification (BS). These probiotics were encapsulated in different solutions encompassing various contents of alginate, gelatin, and gellan gum. The RVS bead diameters was about 1.5 times bigger and hardness was 70%-80% lower than BS samples. As determined by Raman spectral mapping, the RVS beads had two calcium alginate walls but the BS beads had only one. The inner wall of the RVS beads was more than three times thicker than outer wall. The encapsulation yields of gelatin/gellan gum and gelatin beads prepared by both methods were >1.5% alginate beads. All the RVS-prepared beads were resistant to stomach acid and showed no significant reduction in the intestine. Furthermore, the incorporation of gelatin and gellan gum into alginate led to higher cell protection. For 1.5% alginate beads, <67% survival was achieved after acid exposure but in others, >77% survival was observed; RVS beads were about 1 log above than BS ones. The proposed novel microencapsulation method efficiently increased the viability of probiotic bacteria compared to the conventional approaches.

The effects of Shirazi thyme (Zataria multiflora) oil nanoemulsion on the quality of shrimp (Litopenaeus vannamei) during refrigerated storage.

The effects of carboxymethyl cellulose (CMC) coating incorporated with Shirazi thyme (Zataria multiflora) oil nano emulsion (SNE), in different concentrations (10, 20, and 30 mg/ml), on the melanosis and the quality of Pacific white shrimp (Litopenaeus vannamei) was investigated during 10 days in refrigerated temperature (4 ± 0.5 °C). The results showed that incorporating SNE into CMC could significantly (P < 0.05) improve the microbial and lipid oxidation quality of the shrimp. During storage, the incremewnt of total volatile basic-nitrogen and trimethylamine in the SNEs-treated groups were lower than that of the other groups (P < 0.05). Also, the application of SNEs improved the textural, melanosis, and sensory acceptability of the coated shrimps. However, treating the shrimp with SNE in 30 mg/ml concentration caused an increase in the a* and b* values of samples and a decrease in the acceptability of this group. Hence, the SNE incorporation at lower concentrations (10, 20 mg/ml) into CMC coating could be useful in extending the shelf life of the shrimp during refrigerated storage and could be a substitute for sodium metabisulphite.

Multidrug-resistant Salmonella strains from food animals as a potential source for human infection in Iran.

This study aimed to determine the frequency and characterization of Salmonella isolates from food-producing animals and human diarrheal samples in Shiraz, Iran. Overall, 105 Salmonella isolates were obtained from chicken meat (70/100, 70.0%), beef (19/100, 19.0%), lamb (11/100, 11.0%), and human stool (5/295, 1.7%). S. Infantis (40.9%), S. Enteritidis (29.5%), and S. Paratyphi B (8.6%) were the most prevalent serotypes. Totally 59.1% of the isolates were multidrug-resistant. High resistance to nalidixic acid (67.6%), tetracycline (62.9%), and trimethoprim-sulfamethoxazole (42.3%) were observed. Mutations in the gyrA and parC genes were detected in nalidixic acid-resistant isolates from chicken meat and human stool. No qnrA, qnrB or qnrS genes were detected. The blaTEM and blaCMY-2 genes were detected in ß-lactam-resistant isolates from beef and lamb. Despite the high genetic diversity of PFGE patterns, some isolates from different sources and times showed identical PFGE patterns suggesting specific Salmonella species circulate between various sources over time.

Inhibition of histamine accumulation by novel histamine-degrading species of Staphylococcus sp. isolated from goats and sheep milk.

Histamine is an active amine compound that occurs in various fermented foods that may cause adverse effects on the human health. Certain microorganisms are able to degrade histamine by an oxidative deamination reaction. Therefore, the present study aimed to quantify histamine-forming and/or -degrading activity of the isolates derived from milk of goat and sheep herds, in Iran, by the capillary zone electrophoresis (CZE) method; and we evaluated the molecular characteristics of staphylococcal isolates. Among 243 staphylococcal isolates, 29 histamine-degrading bacteria were identified. One of these isolates, identified as Staph. epidermidis, No. 605, exhibited the highest activity compared to others, degrading available histamine to 58.33% within 24 h. By polymerase chain reaction (PCR) analysis, the isolate, No. 605 that exhibited remarkable histamine-degrading activity lacked the genes encoding coagulase and DNase, nor did it harbor any of the five classical enterotoxin genes. This is the first report to show that seven Staphylococcus species, including Staph. chromogenes, Staph. aureus, Staph. haemolyticus, Staph. epidermidis, Staph. pseudintermedius, Staph. agnetis, and Staph. hyicus, were able to degrade histamine, which were hitherto not known to have this capacity. Therefore, histamine-degrading activity is a definite criterion to introduce fermenting organisms able to decrease histamine content in different food products.

The effect of cross-linker type on structural, antimicrobial and controlled release properties of fish gelatin-chitosan composite films incorporated with ε-poly-l-lysine.

In this study, active antibacterial cross-linked composite films were prepared through incorporating ε-poly-l-lysine (ε-PLL) into Siberian sturgeon gelatin-chitosan mixture. Cross-linking was performed by Glutaraldehyde (G) and/or Cinnamaldehyde (C). The antimicrobial, ε-PLL release, mechanical and morphological properties were then investigated. The addition of G to the biopolymer mixture significantly resulted in lower water vapor permeability, enhanced mechanical strength, lower moisture content, and water solubility. The FTIR spectra indicated the formation of imine bonds in the composite film network. The microstructure of composite films was affected by the cross-linking agent. The films cross-linked by G and C showed smooth and rough surfaces, respectively. C induced very small pores in the cross-section of the composite film. The composite films incorporated with ε-PLL revealed higher and steady-state in vitro antimicrobial properties against food spoilage bacteria. A higher release of ε-PLL and hence higher antibacterial activity was measured in the matrices cross-linked by C than those cross-linked by G. The results showed that the ε-PLL-fortified fish gelatin/chitosan composite films can be considered as a food-packaging material. G and C, as cross-linkers, can improve the structural and antimicrobial properties of this composite film.

Production and evaluation of the chemical and mechanical properties of nanocellulose and nanowood starch-based biodegradable films potential candidates for moisture absorbers for food packaging.

This study was conducted to prepare starch-based moisture absorbent pads from nanocellulose (NC) and nanowood (NW) particles using solution casting evaporation method and to evaluate their physical and mechanical properties at different thicknesses. The swelling degree (SD), water vapor permeability (WVP), tensile strength (TS), and elongation at break (EB), of prepared biofilms were measured. Structural properties of biofilms were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated that two types of biopolymers showed the highest level of SD at thicknesses lower than 100 µm. The highest level of SD in the lowest time belonged to nanowood biofilm. Nanowood biofilms also showed highest WVP at lower thicknesses. Due to the highest EB and the lowest TS values, improvement was observed in mechanical properties of both nano biofilms. The high hydration capacity and WVP of low-thickness NW films make it a promising candidate for developing biodegradable films with the potential to be used as a moisture-absorbing pad in active food packaging.

Influence of limited replacement of NaCl with KCl and yeast extract on microbiological, chemical, sensory, and textural properties of emulsion-type chicken sausages.

In this study, the production of emulsion-type sausage by replacement of 20% to 40% KCl plus 1% or 2% yeast extract instead of NaCl was studied. The physical, chemical, microbiological, and sensory properties of the samples were analyzed up to 28 days of storage. The sample sausages were approved by the panelists. The physical, chemical, and microbiological properties of emulsion-type sausages were not considerably influenced by these changes. The 40% replaced salt by KCl showed a similar property rather than the regular sausages. The aroma and taste of the sausages improved by using yeast extract. In addition, the adverse flavors resulted from adding KCl were excluded by adding the yeast extract. As a result, production of healthy emulsion-type sausages (having 40% lower NaCl) with acceptable sensory qualities was introduced.

Interaction between the probiotic Bacillus subtilis and Salmonella Typhimurium in Caco-2 cell culture.

BACKGROUND AND OBJECTIVES: Bacillus probiotics have been recently considered in biotechnological researches, and food additives. The present study was aimed to investigate the effects of Bacillus subtilis probiotics (PY79 and ATCC 6633) and their metabolites on Salmonella Typhimurium in Caco-2 cells. MATERIALS AND METHODS: Cytotoxicity of B. subtilis ATCC 6633 crude supernatant (CS) was evaluated by 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. S. Typhimurium invasion assay was performed in the presence of the probiotics. Cell viability, apoptosis, and necrosis were evaluated in presence of S. Typhimurium, B. subtilis strains, and CS (4%, 8%) using flow cytometry. RESULTS: Results showed a significant reduction in the invasive ability of S. Typhimurium to Caco-2 cells by employing B. subtilis probiotics, and CS (p < 0.05). The less invasion was indicated in B. subtilis PY79 and Salmonella co-cultural group. Furthermore, the cell survival rates, and apoptosis/necrosis were respectively increased and decreased in co-culture groups (p < 0.05). CONCLUSION: Hence, it seems that B. subtilis strains could be suggested as beneficial candidates to overcome the invasion and cytotoxicity of Salmonella on the intestinal cells. However, additional in vivo models are suggested to validate our results.

Evaluation of the effect of neutral electrolyzed water and peroxyacetic acid alone and in combination on microbiological, chemical, and sensory characteristics of poultry meat during refrigeration storage.

The objectives of this study were to evaluate the efficacy of near-neutral electrolyzed water (NEW) (100 and 200 µg/ml), peroxyacetic acid (PAA) (200 and 400 µg/ml), and their combination (NEW 100 µg/ml + PAA 200 µg/ml) on microbial quality, pH, TBARS value, and sensory quality of fresh chicken breast meat dipped into the solutions for 10 min at room temperature. Meat samples were tested immediately after treatments and on days 2, 4, and 6 of storage at 4℃. All treatments were effective in reducing microbial populations throughout the storage (P < 0.05), with combined treatment showing the strongest antimicrobial activity. On the sixth day of storage, the aerobic plate counts, psychrophilic plate count, Enterobacteriaceae, lactic acid bacteria, and Pseudomonas counts in the NEW 100 µg/ml + PAA 200 µg/ml group were 1.33, 1.40, 1.45, 1.01, and 1.45 log CFU/g, respectively, which was lower than the control group (P < 0.05). In all treatments, the pH value of meat samples increased with storage time. During 6 days of storage, PAA400 group had the lowest increase in pH value (P < 0.05). On day 6, the combined treatment and PAA 400 µg/ml had the lowest lipid oxidation (P < 0.05). On day 6, the NEW100 + PAA200 group obtained the highest score in sensory attributes compared to other treatment groups (P < 0.05). According to the microbial and chemical analysis, the combined treatment of NEW and PAA can be a promising method to extend the shelf life of chicken by about 2 days at 4℃. Also, these compounds do not contain any harmful residues in chicken breast meat and their use is recommended in decontamination of poultry meat.

Effects of two probiotic spores of Bacillus species on hematological, biochemical, and inflammatory parameters in Salmonella Typhimurium infected rats.

Salmonella infections have become a major health concern in recent decades. This pathogen has evolved to become resistant to antibiotics, which has caused problems in its treatment. As such, finding a novel preventive method is important in the treatment and management of this infection. In recent years, uses of probiotics, especially spore-former genera such as Bacillus spp. has become increasingly popular. In this study spores of two probiotic bacteria, Bacillus subtilis and Bacillus coagulans were fed to rats for three weeks through their daily water intake after which Salmonella Typhimurium was gavaged to the rats. On days 1, 3, 5 and 7 after gavaging, the number of Salmonella was counted in liver, spleen, mesenteric lymph nodes, feces and content of ileum and cecum. Hematological and biochemical parameters, inflammatory mediators, total antioxidant capacity and malondialdehyde were also measured. The results showed that B. subtilis and B. coagulans caused delation in infiltration of Salmonella into the lymph nodes, spleen and liver, reduction of the inflammatory mediators, and decreases in oxidative stress, hematological and biochemical changes. The overall count of Salmonella in the above mentioned parameters has also decreased and a faster return to normal base were also witnessed. The results showed that the use of B. subtilis and B. coagulans can potentially help boost the body's immune system, to combat the effects of exposure to the Salmonella pathogen.

The morphological and biological characteristics of a virulent PI phage isolated from slaughterhouse sewage in Shiraz, Iran.

BACKGROUND AND OBJECTIVES: Foodborne pathogens are among the serious problems all around the world and thus a novel and natural strategy to control and to inhibit such pathogens is highly demanded nowadays. The aim of this study was to isolate a specific bacteriophage of Escherichia coli O157:H7 from sewage in Fars province, Iran to determine its morphological and antimicrobial activities. MATERIALS AND METHODS: In order to isolate the bacteriophage of E. coli O157:H7, 10 samples of slaughterhouse wastewaters were used. Double-Layer Agar method was employed to isolate the bacteriophage. To identify the fine structure of the bacteriophage, electron microscope was employed. Host range and antibacterial activity of the phage was also investigated, in vitro. RESULTS: The morphological and biological characteristics of a virulent Siphoviridae phage, PI, are reported. It was found that infection of E. coli O157:H7 strains with this specific bacteriophage produce clear plaques. In the one-step growth analysis, it was confirmed that the phage has been characterized with a very short rise period (around 15 min), an average burst size of 193 PFU/cell, high infectivity and potent lytic action. The bacteriolytic activity of PI was also investigated, in vitro. It was also clarified that at the MOI of 100, 10 and 1, the phage rapidly lysed the bacterial cells within 0.5 or 2 h. CONCLUSION: These results indicate that the phage PI is a newly discovered phage against E. coli O157:H7 in Iran which may be recommended to use as bio-control purposes.

The effects of supplementation of Bacillus subtilis and Bacillus coagulans spores on the intestinal microflora and growth performance in rat.

BACKGROUND AND OBJECTIVES: The intestinal microflora has an important role in the health status. Since probiotics can balance the intestinal microflora, they have a lot of health beneficial effects. So the appropriate selection of probiotics can cause health-promoting effects. In this study, the combined effects of Bacillus subtilis and Bacillus coagulans on the intestinal microflora and growth performance in rats were investigated. MATERIALS AND METHODS: 80 male rats were divided into the treatment (receiving 5×107 spores/ml of B. subtilis and 5×107 spores/ml of B. coagulans for three weeks in daily water) and control (tap water without probiotics) groups. The total aerobic and anaerobic microorganisms, lactic acid bacteria (LAB), coliforms and spores were weekly counted in the fecal samples. Additionally, the water and feed consumption, the weight gain and Feed Conversion Ratio (FCR) were calculated for each week. RESULTS: The probiotics significantly increased the total aerobic, LAB and spore counts and caused significant reduction in the anaerobe and coliform counts. Following three weeks of probiotic administration, the number of anaerobic bacteria, and coliforms were reduced by up to 0.7 and 1.18 log and the number of aerobic bacteria, LAB and spores were increased by 1.29, 1.15 and 7.2 log respectively. Also, the results showed the feed consumption reduction, weight gain and FCR enhancement in the probiotic group (p < 0.05). CONCLUSION: Supplementation the spores of B. subtilis and B. coagulans improved the growth performance and was beneficial to the intestinal microbiota in rats.

Antimicrobial spectrum activity of bacteriocinogenic Staphylococcus strains isolated from goat and sheep milk.

Bacteriocins have attracted great attention as potential alternatives to antibiotics and chemical food additives. In the present study, 243 Staphylococcus isolates from milk samples (n = 110) of goat and sheep herds located in Fars province, Iran, were screened for antimicrobial substance production. Twenty-eight isolates showed an antagonistic activity against the indicator strain Micrococcus luteus ATCC 4698. The susceptibility of all antimicrobial substances to proteolytic enzymes allowed us to consider them as bacteriocin-like inhibitory substances (BLIS). The term BLIS is applied to uncharacterized proteinaceous antimicrobials produced by gram-positive bacteria. Based on molecular identification methods, the isolates belonged to the species Staphylococcus chromogenes, Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus pseudintermedius, Staphylococcus aureus, and Staphylococcus agnetis. Pulsed-field gel electrophoresis revealed a high level of genotype diversity among the Staph. chromogenes isolates. All of the isolates harbored nukA or bsaA2 genes, suggesting that their BLIS were related to nukacin or Bsa. The antimicrobial compounds from test strains were not effective against gram-negative pathogens, including Salmonella enterica serovar Typhimurium, Escherichia coli O157:H7, and Klebsiella pneumonia as well as the indicator mold Aspergillus fumigatus. All the gram-positive targets, including Bacillus cereus, Listeria monocytogenes, Enterococcus faecalis Ef37 (a tyramine-producer strain), Lactobacillus saerimneri 30a (a histamine-producer strain), and methicillin-resistant Staph. epidermidis, were inhibited by the Staph. chromogenes isolates. Staphylococcus haemolyticus 4S12 was able to inhibit the majority of gram-positive bacteria. Listeria monocytogenes strains were the only indicators sensitive to the antimicrobial agents produced by Staph. agnetis 4S97B. The other Staphylococcus strains were ineffective on all the organisms tested. Based on their inhibitory capacities, the BLIS produced by the Staph. chromogenes isolates seem to be interesting candidates for developing novel antimicrobial agents.