[Antimicrobial effect of probiotics in combination with prebiotics against Staphylococcus aureus and Listeria monocytogenes]

Background and Objective: Probiotc bacteria have benefical effect on consumer health. This study was done to investigate the antimicrobial effect of several probiotic in combinations with different prebiotics against food patoghenic bacteria including Staphylococcus aureus and Listeria monocytogenes

Methods: In this descriptive - analytical study, probiotics including Lactobacillus plantarum, L. acidophilus, L. fermntum, L. casei and L. rhamnosus with prebiotics [1%] including raffinose, lactulose, inulin and trehalose were cultured in MRS broth for 24 hours at 30[degree]C in anaerobic conditions. Antimicrobial property of them was determined with well diffusion plate's method

Results: Probiotics in the presence of prebiotics indicated the higher antimicrobial effect compared to probiotics alone [P<0.05]. The application of prebiotics such as L. casei with raffinose showed higher antimicrobial property against Listeria monocytogenes than the free prebiotics consumption. The diameter of inhibitory growth zone in the presence of raffinose as a prebiotics was 14.66 mm and its absence reduced to 11.75 mm

Conclusion: Antimicrobial effect of probiotics in combination with prebiotics against Staphylococcus aureus and Listeria monocytogenes was higher than probiotics consumption alone

Enzymatic pre-hydrolysis of high fat content dairy wastewater as a pretreatment for anaerobic digestion

Enzymatic extract preparation from Psendomonas aeruginosa KM110 under accession No. HQ730879 with lipase activity [0.3 U/ml], was used to perform enzymatic hydrolysis pretreatment of a synthetic dairy wastewater with 1000 mg/L total fat content. The pretreatment was optimized for 48 h hydrolysis time, at 45[ae%] C with 10% v/v enzymatic extract. The biological treatment of synthetic dairy wastewater was investigated using a batch bioreactor. Both raw and prehydrolyzed wastewater was digested in a batch bioreactor. Enhanced anaerobic digestion efficiency compare to raw wastewater was achieved [chemical oxygen demand [COD], removal efficiency of 90% vs. 66% and biogas production of 4710 ml vs. 2330 ml after 13days]. The results obtained in this study illustrated that the application of a pretreatment process to hydrolyze and dissolve fats may improve the biological degradation of fatty wastewaters, accelerating the process and reducing time of anaerobic digestion. Moreover, the pretreatment of wastewater from several sources is a new and promising application for Upases

Isolation and identification of a novel, lipase-producing bacterium, Pseudomnas aeruginosa KM110

Lipases are particularly important due to the fact that they specifically hydrolyze acyl glycerol, oils and greases, which is of great interest for different industrial applications. In this study, several lipase-producing bacteria were isolated from wastewater of an oil processing plant. The strain possessing the highest lipase activity was identified both biochemically and sequencing of 16S rRNA gene. Then we increase lipase activity by improving conditions of production medium. Also, lipase from this strain was preliminarily characterized for use in industrial application. The 16S rRNA sequensing revealed it as a new strain of Pseudomonas aeruginosa and the type strain was KM110. An overall 3-fold enhanced lipase production [0.76 U mL[-1]] was achieved after improving conditions of production medium. The olive oil and peptone was found to be the most suitable substrate for maximum enzyme production. Also the enzyme exhibited maximum lipolytic activity at 45°C where it was also stably maintained. At pH 8.0, the lipase had the highest stability but no activity. It was active over a pH range of 7.0-10.0. The lipase activity was inhibited by Zn[2+] and Cu[2+] [32 and 27%, respectively] at ImM. The enzyme lost 29% of its initial activity in 1.0% SDS concentration, whereas, Triton X-100, Tween-80 and DMSO did not significantly inhibit lipase activity. Based on the findings of present study, lipase of P. aeruginosa KM110 is a potential alkaline lipase and a candidate for industrial applications such as detergent, leather and fine chemical industries

[Prevalence of nano structure S-layer and beta-lactamase in Bacillus cereus strains]

S-layer is the outer protein layer in the most archaea and bacteria. S-layer protects bacteria against phagocytosis and prohibits entry of some biomolecules and some antibiotics and adhesion to matrix proteins. S-layer is a virulence agent in bacteria, beta-lactamase can inactive [beta-lactame antibiotics. According to role of beta-lactame antibiotics in the treatment of infectious diseases with Bacillus spp., increasing frequency of S-layer and beta-lactamase producer Bacillus cereus strains in hospitals lead to increase antibiotic resistant nosocomial infections. In this basic study, 274 samples were evaluated with laboratory methods in Alzahra hospital and Isfahan University between 2004 and 2006. Bacterial identification was performed with microbiological methods, such as staining, chemical test, use of differential and selective Bacillus cereus selective agar media. Bacteria cultured in TSA for 16h, and then separated surface proteins, and finally electrophoresis was performed. S-layer in Bacillus cereus has 97KD molecular weight. Production of beta-lactamase was evaluated by acidometric method. Of 247 isolated bacteria, frequency of Bacillus cereus strains, S-layer and beta-lactamase in S-layer producer Bacillus cereus strains were 9.49%, 46.20% and 100%, respectively. Results showed high prevalence of nano structure S-layer and beta-lactamase producer Bacillus cereus strains in hospital. We recommend controlling bacterial population in crowded places and health and therapeutic centers to decrease producing antibiotic resistance bacteria

[ study of antibacterial effect of humulus lupulus on some of gram positive and gram negative bacteria]

In recent years, a new view has been stablished toward pharmaceutical plants and applicational use of them all over the world and researchers, in various medical courses are investigating about this issue. On this basis, antibacterial effect of Humulus lupulus, the pharmaceutical plant which has an important place in traditional medicine of Iran, was evaluated on some of bacteria. Based on scientific methods after being dried, prepared extract by using macerasion method. Antibacterial effects of ethanol extract were studied on Staphylococcus aureus [1112PTCC], Escherichia coli [1276PTCC], Bacillus subtilis [1023PTCC], Psedomonas aeroginosa [1430PTCC], by using spreading method, well plate method and MIC. The ethanol extract of Humulus lupulus showed antimicrobial activity on S. aureus and B. subtilis. The extract exhibited antimicrobial activity at a range of 125 mg/ml to 62/5 mg/ml against S. aureus and B. subtilis respectively. With the increase of worldwide antibiotic resistance of many strains of disease producing bacteria, there is a need to access new and complementary approaches to antibiotic therapy. Extract of Humulus lupulus has antibacterial effect. The antimicrobial activities of Humulus lupulus against a variety of gram positive bacteria confirm its use for treatment of infectious

Comparing the frequency of beta-lactamase enzyme existence in isolated nosocomial infection bacteria

beta-lactame antibiotics are very important in the cure of diseases, beta-lactamase as a virulence agent causes resistance to these antibiotics. Existence of beta-lactamase in the pathogen bacteria can cause delay in the treatment. The aim of this research was to compare the frequency of beta-lactamase enzyme existence in different types of isolated nosocomial infection bacteria in Alzahra hospital, Isfahan, Iran. This laboratory study was performed in Alzahra hospital of Isfahan in 2005-2006. According to sample size estimation, 100 infection samples [blood, urine, skin] were randomly selected. Identification of bacteria was performed using microbiological methods; such as: staining, chemical test, and use of differential and selective media. To determine beta-lactamase production in bacteria, acidimetric method was used. Data was analyzed using descriptive statistics. From the 100 isolated pathogen bacterias, 68.45% produced beta-lactamase; 83.33% produced Staphylococcus spp. 70.95% produced Enterobacteriaceae spp. and 18.8% produced Pseudomonas 18.8%. Based on the results, the frequency of beta-lactamase Enzyme existence in isolated bacteria of nosocomial infection was very high, which can be due to the increase of resistance of beta-lactam antibiotics in pathogen Bacteria

Effect of anti-microbial fiber and its interaction with penicillin G on opportunistic skin micro-flora

The standard of hygiene in daily life and hospitals can be increased by the use of new antimicrobial fibers, which diminish the danger of pathogenic bacteria. In this study, the antimicrobial effect of special fibers on some staphylococcus isolates was investigated. The antimicrobial effect of special type of fibers produced in Isfahan Poly Acryl Plant on three species of Staphylococcus aureus, epidermidis and lugdunensis isolated from 96 samples of hand and foot skin micro-flora was studied. The sensitivity of strains regarding resistant strains, to various antibiotics and beta-lactamase enzyme production was studied. The most resistance to antibiotics and beta-lactamase producer were chosen. Using the cup plate method, the inhibiting effect of pure antimicrobial agent on these strains was proven. Next, using shake flask method the effect of antimicrobial fiber on these strains was studied. In order to compare the effect of the antimicrobial agent of the fiber with that of penicillin G, the minimal inhibitory concentration [MIC] of the fiber antimicrobial agent and of penicillin G was tested on the strains. The effect of the interaction of these two antimicrobial agents and their fractional inhibitory concentration [FIC] on the chosen strains was studied using checkerboard method. The results show a significant effect by antimicrobial fiber with 30%, 60% and 100% antimicrobial agent on Staphylococcus species after 24 hrs. Moreover despite the high level MIC of penicillin G on these bacteria [8-256 mg/ml], the MIC of the pure antimicrobial agent of fiber at a level of 10-4 ml/ml caused growth inhibition. The interaction of these two antibacterial agents on the chosen strains was evaluated as synergism. According to this study the antimicrobial effect of the fiber on growth inhibition of common, resistant skin bacterial flora is positive and therefore may be used after other successful clinical trials

[ effect of lactobacillus fermentum ATCC9338 as a probiotic on the adhesion of oral streptococci in vitro]

Oral Streptococci especially Streptococcus mutans are the major cause of dental caries and periodontal diseases. Going along with the increasing antibiotic resistance of bacteria, new methods for decreasing of oral cavity pathogens must be investigated. The aim of this study was to determine the effect of lactobacillus fermentum ATCC9338 as a probiotic strain on the adhesion of oral streptococci to the surfaces. S. mutans ATCC35668 with oral streptococci isolated from dental plaque and caries [40 isolates] were studied. The ability of biofilm formation was investigated using the colorimetric method. An isolates showing the strongest activity in forming biofilm were selected. Then the effect of probiotic strain on the adhesion of the selected isolate to the polystyrene microtiter plate was determined simultaneously and 30 minutes before streptococci entrance to the system. This study showed that in the presence of probiotic strain, the streptococcal adhesion were reduced, and this reduction was significantly stronger if the probiotic strain was inoculated to the system before the oral bacteria. Adhesion reduction is likely due to bacterial interactions and colonization of adhesion sites with probiotic strain before the presence of streptococci. Adhesion reduction can be an effective way on decreasing cariogenic potential of oral streptococci

relationship between cell surface hydrophobicity and antibiotic resistance of streptococcal strains isolated from dental plaque and caries

Bacterial adhesion is governed by specific and nonspecific interactions such as hydrophobicity. Hydrophobic interactions play a role in the adherence of microorganisms to a wide variety of surfaces and facilitate biofilm formation due to bacterial adhesion. In this article the relation between cell surface hydrophobicity and antibiotic resistance was studied. We studied antibiotic susceptibility of isolated Streptococci from dental plaque and caries [by disk diffusion method] and cell suface hydrophobicity [by microbial adhesion to hydrocarbon]. The results indicated that the mean surface hydrophobicity of all mutans and other than mutans Streptococci, without considering their location [caries or plaque] showed significant differences [mean 78%, 59%, respectively], No significant differences among caries and plaque isolated Streptococci were found regarding the antibiotic susceptibility. Chi square test with contingency table showed significant qualitative correlation between classes of hydrophobicity [high, moderate and low] and antibiotic resistance [p= 0.001], but according to the regression models we could not find any linear correlation between cell surface hydrophobicity and the diameter of inhibition zone for each antibiotic separately. The high overall proportion of hydrophobic bacteria found in this study suggests that cell- surface hydrophobicity may play a role in adherence of certain oral species to the tooth surface. If bacteria attach to surfaces and form biofilm they can be more resistant, but these two factors [antibiotic resistance and cell surface hydrophobicity] did not show a linear correlation in this study

[ effect of nisin on biofilm-forming and pathogenic bacteria using micro titer plate method]

Some of pathogenic and food spoilage bacteria may attach on food contact surfaces and form biofilms, which is the sources of food contaminations and distribution of diseases caused by these bacteria. Nisin is a peptidic bacteriocin, which used for biological control of microbial biofilm formation. Also, nowadays, nisin is used in combination with packaging materials to protect food products from contamination with pathogenic bacteria and spoilage. The aim of this study was to assess the effect of different concentrations of nisin on biofilm-forming bacteria. In this experimental research, using micro titer plate method, the effect of different concentrations of nisin on Salmonella enteritidis, Listeria monocytogenes and Staphylococcus aureus was investigated. Using ELISA reader and triphenyl tetrazolium chloride [TTC], the reduction of biofilm-forming bacteria and bactericidal effect of nisin were determined. Data were analyzed by ANOVA and Tukey-Kramer tests, using Minitab software. The results indicated that nisin, in permissive concentration [4 103 IU/ml], is more effective on S. enteritidis biofilm than on L. monocytogenes and S. aureus biofilms with the percentages of 87%, 57%, and 30%, respectively [P<0.05]. The finding of this study showed tat increase upper that permissive concentration of nisin isn't effective on the amount of bacteria or bactericidal effect, however, in permissive concentration has more effect in deletion of bioflm bacteria [S. enteritidis]

Effect of antimicrobial fibers on the resistant strains of staphylococcus isolated from wounds

Some needs of patients can be provided by application of antimicrobial fibers in fabrics preparation. The aim of this study was to assess the antimicrobial effect of a particular kind of these fibers. The antimicrobial fibers were produced by Isfahan Poly Acryl company. We studied three resistant Staphylococcus aureus strains, one Staphylococcus epidermidis strain and one standard Staphylococcus aureus strain [ATCC6538p=PTCC1112]. At first sensitivity of sample strains to the controlling effect of pure antimicrobial agent was proved, and then their MIC was determined with agar dilution method. In the next stage, the effect of antibacterial activity of antibacterial fibers on these strains was studied before and after washing. The effect of antimicrobial pure agent of fibers was compared with the effect of penicillin G as the first selected antibiotic for treatment of Staphylococcus originated infections. Antimicrobial fibers containing 30%, 60% and 100% antimicrobial agent had significant effects on Staphylococcus strains after 24 hours. In spite of the high MIC of penicillin G on these bacteria [32-64 microg/ml], the antibacterial pure agent of fibers with a MIC about 10-4 microl/ml inhibited the bacteria growth. The results confirmed the antibacterial activity of examined fibers in preventing and controlling nosocomial infections resulted from Staphylococcus sp. We hope that clinical trial in the near future would provide the possibility of using these fibers in clinical experiences

Microbial demetallization of crude oil using Aspergilus sp.: vanadium oxide octaethyl porphyrin [VOOEP] as a model of metallic petroporphyrins

An isolate from polluted soil identified as Aspergillus sp. MS-100 was able to consume vanadium oxide octaethyl porphyrin as a model for protoporphyrins in crude oil. The isolate degrades about 55% of vanadium oxide octaethyl porphyrin [VOOEP] under optimum conditions during 7 days. The release of more than 0.96 mgL-1 of free vanadium into the aqueous phase was confirmed using atomic absorption. By using the Taguchi experimental design method, the optimum values of pH, temperature and initial concentration of VOOEP were determined as 5.5, 30C, and 20 mg/l, respectively. The reduction of VOOEP in the culture medium was accelerated by Ag+ and inhibited by Zn2+ and EDTA. The Sn2+ and Pb2+ ions showed a stimulatory effect at 0.1 mM and an inhibitory effect at 1 mM