Search

The objective of this study was to evaluate the inhibitory effect of lactic acid (LA) and peroxyacetic acid (PAA) on the biofilm formation of Escherichia coli O157:H7 in beef extract (BE). BE mediu...

Hyaluronic acid finds its complete application in areas such as therapeutics, cosmetics, and as a health supplement. In the present investigation, standardization for the production of hyaluronic acid by Streptococcus equisimilus MK156140 in complex media was performed. Some of the selected physicochemical parameters such as pH, temperature, speed, incubation time, sucrose, yeast extract, and beef extract were screened using Plackett-Burman foldover design. Further, the screened parameters interaction was investigated using central composite design (CCD) and closely compared with OVAT studies. At a pH of 7.38, with beef extract, 12.15%, and yeast extract 7.64%, the observed yield was 7.16 g/L, which was in close line with the predicted value of 7.21 g/L.

Phi 6 (Φ6) bacteriophage is a proposed surrogate to study pathogenic enveloped viruses including SARS-CoV-2-the causative agent of COVID-19-based on structural similarities, BSL-1 status, and ease of use. To determine the role of virus-contaminated hands in disease transmission, an enhanced understanding of buffer and method performance for Φ6 recovery needs to be determined. Four buffer types and three methodologies were investigated for the recovery of Φ6 from human fingerpads over a 30 min duration. Phosphate buffered saline (PBS), PBS + 0.1 % Tween, 0.1 M glycine + 3% beef extract, and viral transport medium were evaluated as buffers for recovery of Φ6 via a dish, modified glove juice, and vigorous swabbing method. Φ6 concentrations on fingerpads were determined at 0-, 5-, 10-, and 30-min post-inoculation. While there were observed differences in virus recovery across buffer and method types depending on the time point, log PFU recovery based on buffer type or methodology was not significantly different at any time point (P > 0.05). The results presented in this study will allow for future work on Φ6 persistence, transfer between hands and surfaces, and efficacy of hand hygiene methods to be performed using a well-characterized and validated recovery method.

In recent years, the potential application of plasma-activated water (PAW) in the food industry has received increasing attention as a promising alternative to traditional sanitizers. The objective of this work was to evaluate the effect of organic matters in the form of beef extract or peptone on the inactivation efficacy of PAW against Escherichia coli O157:H7 and Staphylococcus aureus. PAW was mixed with beef extract or peptone (final concentration: 0–5.0 g/L) and the mixture was allowed to stand at room temperature for 15 min. Subsequently, 100 μL of each bacterial suspension was treated with 900 μL of the PAW/organic matters solutions at room temperature for another 6 min. The results showed that PAW treatment without organic matters could effectively inactivate the tested bacteria, resulting in 3.70-and 2.32-log reduction of E. coli O157:H7 and S. aureus in comparison to the control group, respectively. Beef extract or peptone severely quenched the inactivation efficacy of PAW against E. coli O157:H7 and S. aureus in a dose-dependent way. The addition of beef extract and peptone significantly decreased the oxidation-reduction potential and NO2− concentration of PAW, increased the pH values of PAW in a dose-dependent manner (p 0.05). Thus, more attention should be paid to the effect of interfering substances on the disinfection efficacy of PAW before its practical application.

Physiological fatigue and toxic effects are commonly associated with chemotherapy. Beef extract (BE) is a nutritional supplement obtained by cooking beef. The present study examined the effects of several BE concentrations on 5-fluorouracil (5-FU)-induced fatigue and toxic effects in mice. Results showed BE supplementation ameliorated 5-FU-induced body and organ weight loss. All BE + 5-FU groups demonstrated increased grip strength (135.3–163.2 g), endurance time (567.3–911.3 s), and movement distance (23623–31225 cm) when compared with the 5-FU group (97.6 g, 265.2 s, and 13916 cm). Hepatic and muscular (0.76 and 1.06 mg/g) glycogen levels were maintained in the BE-3x + 5-FU group when compared with the 5-FU group (0.44 and 0.58 mg/g). Moreover, catalase (liver and muscle) and glutathione peroxidase (liver) activities were enhanced. The serum alanine aminotransferase, aspartate aminotransferase, and histopathological changes were ameliorated in the BE-2x + 5-FU and BE-3x + 5-FU groups. BE supplementation could provide a novel strategy for managing 5-FU-induced fatigue and toxic effects.

Questin has favorable applications. Fractional factorial design, Box–Behnken design, and response surface methodology were adopted to optimize the fermentation conditions of the marine-derived fungus, Aspergillus flavipes HN4-13, thereby enhancing questin production. Optimal fermentation conditions in a 500-mL conical flask with 200 mL of medium were 4% soluble starch, 0.9% beef extract, 4% NaCl, 0.05% Na(2)HPO(4), pH 6, 2% inoculum size, and shaking at 28 ℃ and 160 rpm/min for 7 days. The production of questin can achieve 64.93 ± 4.55 mg/L, with no significant difference from the predicted value (66.27 mg/L). Thus, this optimized process of questin production is feasible. Such production is 17-fold higher than that of the basal Sabouraud’s dextrose medium. Results indicate the potential of A. flavipes HN4-13 in the large-scale production of questin through fermentation.

Systematic and sequential optimization strategy based on statistical methodology involving one factor at a time approach was used to enhance PHA production by Bacillus subtilis NCDC0671 using orange peel hydrolysate-based medium in shake flask cultures. Medium components exerting a significant influence in PHA production were screened out using the Plackett–Burman design. Following Box–Behnken method, three significant factors influencing PHA production were identified as beef extract, sodium chloride and incubation period. The optimum concentration and interaction effect of these three components were determined by RSM based on Box–Behnken design. The model developed was validated, and the optimum medium containing 2.23 (g/L) beef extract, 0.72 (g/L) sodium chloride and 48 h of incubation period led to maximum PHA production of 5.09 g/L, which was 2.49-fold higher than the unoptimized medium. The ANOVA results established the significance of the model (p

Hepatitis A virus (HAV) can cause serious liver disease and even death. HAV outbreaks are associated with the consumption of raw or minimally processed produce, making it a major public health concern. Infections have occurred despite the fact that effective HAV vaccine has been available. Development of a rapid and sensitive HAV detection method is necessary for an investigation of an HAV outbreak. Detection of HAV is complicated by the lack of a reliable culture method. In addition, due to the low infectious dose of HAV, these methods must be very sensitive. Current methods rely on efficient sample preparation and concentration steps followed by sensitive molecular detection techniques. Using green onions which was involved in most recent HAV outbreaks as a representative produce, a method of capturing virus particles was developed using carboxyl-derivatized magnetic beads in this study. Carboxyl beads, like antibody-coated beads or cationic beads, detect HAV at a level as low as 100 pfu/25g of green onions. RNA from virus concentrated in this manner can be released by heat-shock (98°C 5min) for molecular detection without sacrificing sensitivity. Bypassing the RNA extraction procedure saves time and removes multiple manipulation steps, which makes large scale HAV screening possible. In addition, the inclusion of beef extract and pectinase rather than NP40 in the elution buffer improved the HAV liberation from the food matrix over current methods by nearly 10 fold. The method proposed in this study provides a promising tool to improve food risk assessment and protect public health.

This study aimed to investigate the effect of nitrogen sources on the production and rheological properties of welan gum produced by Sphingomonas sp. ATCC 31555. Six different nitrogen sources were used for ATCC 31555 fermentation, and 2 of these were further analyzed due to their more positive influence on welan gum production and bacterial biomass. Bacterial biomass, welan gum yield, welan viscosity, molecular weight, monosaccharide composition, acyl content, and welan structure were analyzed. Welan gum production and the biomass concentration of ATCC 31555 were higher in media containing NaNO3 and beef extract. Welan viscosity decreased at higher temperatures of 30-90°C, and it increased with a higher welan concentration. In the media containing NaNO3 (3 g·L-1), welan viscosity was higher at 30-70°C and a welan solution concentration of 6-10 g·L-1. With a reduced NaNO3 concentration, the molecular weight of welan gum and the molar ratio of mannose decreased, but the molar ratio of glucuronic acid increased. With different nitrogen sources, the acetyl content of welan gum differed but its structure was similar. NaNO3 and beef extract facilitated welan production. A reduced NaNO3 concentration promoted welan viscosity.

This study aimed to improve microbial flocculant production by optimizing the components of a Bacillus subtilis CZ1003 culture medium. Using the flocculation rate as the dependent variable, single-factor experiments were performed and beef extract at a concentration of 9 g/L was found to be the optimal nitrogen source, while glucose at a concentration of 20 g/L was the optimal carbon source. KCl, MgCl2, NaCl, and CaCl2 at concentrations of 0.75, 2.5, 0.5, and 5.0 g/L, respectively, were the optimum inorganic salts, in order of flocculant production activity. Orthogonal experimental demonstrated that KCl played a dominant role for Bacillus subtilis production of bioflocculants, followed by NaCl and CaCl2. Optimization experiments demonstrated that the optimal combination of the two salts was 0.75 g/L KCl and 0.5 g/L NaCl, resulting in a flocculation rate of 36.2% when included together at these concentrations. The final optimized medium consisted of 20 g/L glucose, 9 g/L beef extract, 0.75 g/L KCl, and 0.5 g/L NaCl. Compared with the initial medium, the optimized medium enhanced the flocculation activity from 12.1 to 36.2%, which equates to an increase of 199.17%. Meanwhile, the flocculant yield was increased from 0.058 g/L to 0.134/L, an increase of 131.03%. The optimized medium could be used to improve microbial flocculant production and provides a basis for further exploration.

Methods for recovery of poliovirus type 1 (LSc2ab) from naturally-infected oysters ( Crassostrea gigas ) were examined. Extraction procedures analyzed included glycine-saline and polyelectrolyte (Cat-Floc) methods followed by concentration using modifications of an acid precipitation technique, Direct viral assay of shellfish homogenates, when compared to virus recovery following extraction, indicated that substantially fewer viruses were detected in initial homogenates. These data appeared to support the contention that input values based on homogenate assay were inappropriate in determining recovery efficiencies with naturally-infected shellfish. Since absolute efficiencies could not be determined, relative efficiencies using samples from pooled homogenates were used to determine the recovery efficiencies of various extraction procedures. Cat-Floc extraction followed by a beef extract-modified acid precipitation technique resulted in higher virus recoveries than a glycine-saline extraction procedure.

Beef extract (BE) is a nutritional supplement obtained by cooking beef meat. Compared with traditional chicken essence or clam extract, BE is cheaper to produce and may be used for wound healing, as a chemotherapy supplement, or to prevent fatigue. In this study, we evaluated the potential beneficial effects of BE on exercise performance and the related role of the gut microbiota. Pathogen-free male BALB/c mice were divided into three groups to receive vehicle or BE (0, 12.3, or 24.6 mL/kg) by oral gavage for 28 days. Exercise performance was evaluated using forelimb grip strength, swimming time to exhaustion, and physiological levels of fatigue-related biomarkers (serum lactate, blood urea nitrogen, and glucose levels) after physical challenges. BE supplementation elevated endurance and grip strength in a dose-dependent manner, significantly decreased lactate and blood urea nitrogen levels after physical challenge, and significantly increased muscle glycogen content. The germ-free mice supplemented with BE or an equal-calorie portion of albumin did not show significant differences from the other groups in exercise performance and levels of related biomarkers. Therefore, BE supplementation improved endurance and reduced fatigue, which might be related to BE composition, but had no correlation with the gut microbiota.

164 strains of Antagonistic bacteria were isolated from 131 mature-period soil samples from eight counties in Bijie City, Guizhou Province, China. In this study, the antagonistic bacteria that inhibited Alternaria alternata were screened and isolated. In addition, the antagonistic strain L2 was identified as Bacillus megaterium. Influencing factors also demonstrated that the suitable conditions for the production of antibacterial substances by strain L2 are as follows: liquid volume 50 mL/500 mL at pH 7.0 and 30°C under oscillation culture conditions, with beef extract as the carbon, nitrogen source.

In this study, response surface methodology (RSM) was employed for the optimization of bioprocess parameters for enhanced extracellular protease production by a native Bacillus aryabhattai Ab15-ES. Preliminary screening of various nutritional parameters by one factor at-a-time approach revealed that maltose and beef extract were the best carbon and nitrogen sources, respectively, that considerably influenced the enzyme production. The quadratic model of RSM for protease production was significant (p

There is increasing interest in methodologies for the simultaneous concentration and detection of multiple targets in individual samples. The aim of this study was to investigate the potential presence of E. coli DNA in beef extract powder used as part of a procedure to concentrate water samples for the simultaneous detection of bacteria, viruses and protozoa. DNA from E. coli was detected in five out of six beef extract lots tested, demonstrating the limitations of its inclusion when being used in assays that will be used for the detection of E. coli in water samples. Further work is required to clarify if this phenomenon also occurs for other microorganisms of interest in water.

Isaria farinosa is a pathogen of alpine Thitarodes larvae that are hosts for the Chinese medicinal fungus, Ophiocordyceps sinensis. A matrix analysis indicated that the optimal culture conditions for the mycelial growth of I. farinosa are a 50-mL liquid broth in a 250-mL flask at more than 100-rpm rotation and 15–25 °C. Illumination does not affect the mycelial growth. The optimal nutrition requirements are D-(+)-galactose and D-(−)-fructose as carbon resources and D-cysteine as well as yeast powder, peptone, and beef extract as nitrogen resources at a carbon-to-nitrogen ratio of 1:1 to 1:7. The mineral component and vitamins also significantly increase the mycelial growth of I. farinosa. Based on the optimal culture conditions and nutrition requirements for the mycelial growth of I. farinosa, the effects of altitude on mycelial growth and its metabolome were evaluated using quadrupole-time-of-flight/mass spectrometry, principal component analysis and partial least squares discriminant analysis. The altitude did not affect the mycelial production but significantly regulated its metabolome. The study presents a new approach to better select a method for producing more useful metabolites and highlights the necessity of establishing standards for culturing methods related to altitude to preserve fungal quality; additionally, the results indicate that the use of a fermenter may meet the demands of large-scale mycelial production.

Physical and chemical factors influencing the anti-leukemic l-asparaginase enzyme production by Bacillus subtilis VUVD001 were optimized using multi-stage optimization on the basis of preliminary experimental outcomes obtained by conventional one-factor-at-a-time approach using shake flasks. Process variables namely carbon, nitrogen sources, pH and temperature were taken into consideration during response surface methodology (RSM) optimization. The finest enzyme activity of 0.51 IUml−1 obtained by OFAT method was enhanced by 3.2 folds using RSM optimization. Artificial neural network (ANN) modelling and genetic algorithm (GA) based optimizations were further carried out to improve the enzyme drug yield. Results were also validated by conducting experiments at optimum conditions determined by RSM and GA optimization methods. The novel bacterium yielded in 2.88 IUml−1 of enzyme activity at optimum process variables determined by GA optimization, i.e., 0.5% glucose, 8.0% beef extract, 8.3 pH and 49.9 °C temperature. The study explored the optimized culture conditions for better yielding of anti-leukemic enzyme drug from a new bacterial source namely Bacillus subtilis VUVD001.

Aims The objective of this research is to evaluate eluents for recovery of an enveloped bacteriophage, Φ6, using whole-hand sampling. Methods and Results Virus was applied to the hands of volunteers and sampled by the glove juice method with 1·5% beef extract (BE), phosphate buffered saline (PBS), 0·01 and 0·1% Tween 80, tryptic soy broth (TSB) and 9% NaCl. Each volunteer underwent multiple rounds application and hand sampling. Mean log10 virus loss across trials was 2·6 for BE, 2·8 for PBS, 2·4 for TSB, 3·8 for NaCl, 3·0 for 0·1% Tween 80, and 2·9 for 0·01% Tween 80. Within each volunteer, there was a decline in viral loss from the first to last trial. Conclusions These eluents can recover Φ6 from hands with approx. 2–3 log10 loss, comparable to recoveries previously reported for influenza. Protein and detergent-based eluents may have similar recoveries, but recovery may still vary across repeated sampling. Significance and Impact of the Study Based on current work, protein-based eluents such as beef extract can maximize recovery of enveloped viruses during hand sampling, providing methods for evaluating survival and transmission of enveloped viruses on hands. Further exploration is needed of the effect of repeated sampling on recovery from whole-hand sampling.

Lime fleshing waste is one of the major hazardous solid wastes from leather industry. Utilization of the waste is one of the appropriate strategies to address the environmental issues and to realize economical returns. A process of preparation of beef extract from limed fleshing waste has been developed. The beef extract prepared is intended for microbial application. According to the process developed, the alkalis present in the fleshing waste were neutralized and removed by washing. Then the fleshing waste was hydrolyzed thermally and the hydrolysate obtained was lyophilized. The prepared product was characterized. The characteristics of the prepared product were compared with those of a widely accepted market product (Hi-Media). The beef extract prepared was found to be in compliance with all the requirements of the relevant standard. The product was also found to perform similarly to Hi-Media beef extract. The chemistry of the product was studied using tools such as FT-IR, HPLC, Maldi-TOF, 13C NMR and 1H NMR. The product chemistry was found to be akin to that of the beef extract of Hi-Media.

For land application, biosolids are classified as Class A or Class B based on the levels of bacterial, viral, and helminths pathogens in residual biosolids. The current EPA methods for the detection of these groups of pathogens in biosolids include discrete steps. Therefore, a separate sample is processed independently to quantify the number of each group of the pathogens in biosolids. The aim of the study was to develop a unified method for simultaneous processing of a single biosolids sample to recover bacterial, viral, and helminths pathogens. At the first stage for developing a simultaneous method, nine eluents were compared for their efficiency to recover viruses from a 100 gm spiked biosolids sample. In the second stage, the three top performing eluents were thoroughly evaluated for the recovery of bacteria, viruses, and helminthes. For all three groups of pathogens, the glycine-based eluent provided higher recovery than the beef extract-based eluent. Additional experiments were performed to optimize performance of glycine-based eluent under various procedural factors such as, solids to eluent ratio, stir time, and centrifugation conditions. Last, the new method was directly compared with the EPA methods for the recovery of the three groups of pathogens spiked in duplicate samples of biosolids collected from different sources. For viruses, the new method yielded up to 10% higher recoveries than the EPA method. For bacteria and helminths, recoveries were 74% and 83% by the new method compared to 34% and 68% by the EPA method, respectively. The unified sample processing method significantly reduces the time required for processing biosolids samples for different groups of pathogens; it is less impacted by the intrinsic variability of samples, while providing higher yields (P = 0.05) and greater consistency than the current EPA methods.

A sweet potato medium (SPM) was formed with extract from baked sweet potatoes supplemented with 0, 4, or 8 g/L of each nitrogen source (beef extract, yeast extract, and proteose peptone #3) to form SPM1, SPM2, and SPM3 respectively. Lactobacilli MRS was used as control medium. Ten Lactobacillus strains containing an average of 2.34 ± 0.29 log CFU/mL were inoculated individually into batches of MRS, SPM1, SPM2, and SPM3. The growth patterns for the tested Lactobacillus strains growing in SPM2 and SPM3 were found to be similar to that in MRS. The average final population after 24 h of incubation in MRS, SPM2, and SPM3 reached 10.41 ± 0.35, 10.59 ± 0.27, and 10.72 ± 0.19 log CFU/mL respectively. SPM2 and SPM3 maintained higher pH values throughout the incubation period than MRS. These findings indicate that SPM2 can be a suitable medium for the growth of Lactobacillus and can provide an alternative at low-cost.

Effects of culture conditions and surfactants on marine lysozyme s-12 production using a statistical approach were studied in this work. Analysis of results were based on statistical calculations carried out with the one factor-at-a-time method and the L16-orthogonal array method, using MINITAB 15.0 software. All the fermentation runs were carried out at 30±2°C on a rotary orbital shaker at 200 rpm for 24 h. The individual components selected affected the fermentation process were CaCl2 > glucose >peptone > beef extract >MgSO4. Furthermore, Tween 80 with 0.4 mM could enhance the production of all the extracellular proteins and S-12. The final optimized medium supported S-12 activity of 1971.25 U/mL at the end of 24 h as compared with 1095.00 U/mL before optimization. Key words: Lysozyme S-12, culture condition, surfactant, optimization, L16-orthogonal array.

Atmospheric cold plasma (ACP) is a non-thermal technology, effective against a wide range of pathogenic microorganisms. Inactivation efficacy results from plasma generated reactive species. These may interact with any organic components in a test matrix including the target microorganism, thus food components may exert a protective effect against the antimicrobial mode of action. The effect of an in-package high voltage ACP process applied in conjunction with common meat processing MAP gas compositions as well as bacteria type and meat model media composition have been investigated to determine the applicability of this technology for decontamination of safety challenges associated with meat products. E. coli, L. monocytogenes, and S. aureus in PBS were undetectable after 60 s of treatment at 80 kVRMS in air, while ACP treatment of the contaminated meat model required post-treatment refrigeration to retain antimicrobial effect. The nutritive components in the meat model exerted a protective effect during treatment, where 300 s ACP exposure yielded a maximum reduction of 1.5 log using a high oxygen atmosphere, whilst using air and high nitrogen atmospheres yielded lower antimicrobial efficacy. Furthermore, an ROS assay was performed to understand the protective effects observed using the meat model. This revealed that nutritive components inhibited penetration of ROS into bacterial cells. This knowledge can assist the optimization of meat decontamination using ACP technology where interactions with all components of the food matrix require evaluation. European Commission - Seventh Framework Programme (FP7)

The main objective of the study is to enhance the cellulase production using Plackett Burman Design (PBD) and Central Composite Design (CCD) by Aspergillus nidulan in Submerged fermentation (SmF). The screening of nine nutrients for their influence on cellulase production is achieved using Plackett-Burman design. Yeast extract, MnSO4·H2O, avicel and beef extract were selected based on their positive influence on cellulase production. The selected components were optimized using Response Surface Methodology (RSM). At the optimum condition, a maximum cellulase production of 11.6 IU/mL was obtained.

The purpose of this research was to enhance the production of vitamin K2 by fermentation optimization and Arachis hypogaea supplementation in Flavobacterium sp. mutant SP-L-01. Optimized culture condition were as follows: 6-days shake-flask culture at 37oC with initial pH value 7.0 ± 0.2, shaking speed in 120 r/min and medium volume of 30 mL with 2% inoculums. After optimization of fermentation medium by response surface methodology (RSM), optimized medium were maltose 23.8 g/l, glucose 9.69 g/l, beef extract 15 g/l, K2HPO4 4.5 g/l，NaCl 3.0 g/l and MgSO4·7H2O 0.3 g/l. Production of vitamin K2 after optimization reached to 10.97 mg/l, which is 79.25% higher than that before optimization (6.12 mg/l). 3 mg/mL of arachis hypogaea was added into the medium at 72 h of shake-flake cultivation, which improved the production of menaquinone-4 (MK4) up to 371% and menaquinone-6 (MK6) up to 149% higher than those of the original medium. D-(+)-catechin, one of the components of arachis hypogaea, was added alone into the medium, which also improved the vitamin K2 synthesis.

Somatic coliphages are present in high numbers in sewage sludge. Since they are conservative indicators of viruses during wastewater treatment processes, they are being used to evaluate the effectiveness of sludge treatment processes. However, efficient methods to extract them from sludge are lacking. The objective was to compare different virus extraction procedures and develop a method to extract coliphages from sewage sludge. Twelve different extraction buffers and procedures varying in composition, pH, and sonication were compared in their ability to recover indigenous phages from sludges. The 3% buffered beef extract (BBE) (pH 9.0), the 10% BBE (pH 9.0), and the 10% BBE (pH 7.0) with sonication were short-listed and their recovery efficiency was determined using coliphage-spiked samples. The highest recovery was 16% for the extraction that involved 10% BBE at pH 9.0. There is a need to develop methods to extract somatic phages from sludges for monitoring sludge treatment processes.

The application of trisodium phosphate (TSP) on produce against food-borne bacteria has not been extensively evaluated. This research studied the effect of 20 and 50 mg/ml TSP in reducing Salmonella Typhimurium (ST) and Listeria monocytogenes (Lm) on model produce (lettuce and peppers). Washed and air-dried Iceberg lettuce (3 × 3 cm 2 ) and Jalapeno peppers (25–30 g) were spiked with S . Typhimurium or L. monocytogenes (∼7 log 10 CFU/ml). Samples were treated with 20 or 50 mg/ml TSP, 200 mg/L sodium hypochlorite (for comparison with traditional washes) or water (control rinse) for 15 or 30 s. Treatments were immediately neutralized with trypticase soy broth (TSB) containing 30 mg/ml beef extract, serially diluted, plated on Xylose Lysine Tergitol 4 (XLT4) agar for ST and Tryptic Soy Agar (TSA) for Lm and incubated at 37 °C for 24–48 h. Results showed that 20 mg/ml TSP and 200 mg/L sodium hypochlorite caused 5–6 log 10 CFU/ml reduction in ST on both lettuce and peppers after 15 s and 30 s, while 50 mg/ml TSP reduced ST to undetectable levels on both produce at both contact times. For overnight Lm cultures, a mere reduction of 0.21 and 0.28 log 10 CFU/ml was obtained using 20 and 50 mg/ml TSP after even 5 min, while 200 mg/L sodium hypochlorite decreased Lm by ∼1 log 10 CFU/ml after 30 s and 1 min on lettuce, and decreased pure culture Lm to undetectable levels after 3 min. Thus, 50 mg/ml TSP appears effective against ST with negligible effects against Lm, whose mode of action needs to be understood.

Aims: To screen and identify biosurfactant producers from petroleum-contaminated soil; to use response surface methodology (RSM) for medium optimization to enhance biosurfactant production; and to study the properties of the newly obtained biosurfactant towards pH, temperature and salinity. Methods and Results: We successfully isolated three biosurfactant producers from petroleum-contaminated soil and identified them through 16S rRNA sequence analysis, which exhibit the highest similarities to Acinetobacter beijerinckii (100%), Kocuria marina (99%) and Kineococcus marinus (99%), respectively. A quadratic response model was constructed through RSM designs, leading to a 57AE5% increase of the growth-associated biosurfactant production by Acinetobacter sp. YC-X 2 with an optimized medium: beef extract 3AE12 g l)1 ; peptone 20AE87 g l)1 ; NaCl 1AE04 g l)1 ; and n-hexadecane 1AE86 g l)1. Biosurfactant produced by Acinetobacter sp. YC-X 2 retained its properties during exposure to a wide range of pH values (5–11), high temperatures (up to 121C) and high salinities [up to 18% (w⁄ v) Na+ and Ca2+], which was more sensitive to Ca2+ than Na+ . Conclusions: Two novel biosurfactant producers were isolated from petroleumcontaminated soil. Biosurfactant from Acinetobacter sp. YC-X 2 has good properties to a wide range of pH, high temperature and high salinity, and its production was optimized successfully through RSM.

Enriching, separating and selecting strains form the soil around Zhengzhou University canteen which has great degradability for cooking oil, b 1 , b 2 , b 3 , b 4 , m 1 , a 1 , among which b 4 is the best. And studied the growth conditions and the degradation conditions of b 4 , the results showed that the optimal growing condition is as follows: carbon source (beef extract) 2.0 g/L, nitrogen source (peptone) 5.0 g/L, shaker rotation speed 150r/min; its optimal degradation condition: initial pH value 5.0, cooking oil concentration 3.0 g/L, degradation temperature 30°C, the degradation rate of oil will stabilize at above 48% after 32 h.

MRS culture medium was used as the basic medium for optimizing the fermented condition of Lactobacillus. rhamnosus. The four significant factors (beef extract, tween-80, peptone, diammonium citrate) were screened from these components by using a Plackeet-Burman design. Steepest ascent path was adopted to approach the optimal region, and then the Central Composite Design was used to determine the optimal levels of the main factors. Considering the fit model, cost and operation, the optimal conditions were determined as follows: beef extract 2.6%, tween-80 0.3%, peptone 2%, diammonium citrate 0.4%, with other components remaining the same, 3% inoculation, 18h culture at 37¡æ.Under such conditions, the experimental value of cell concentration were 3.54×109cfu/ml and 2.19-fold live bacteria counts in MRS-based culture medium, showing no difference with predicted value 3.68×109cfu/ml.