Man Rogosa Sharpe Medium Research Articles

Enhancement of Bioactive Compounds and Survival of Lactobacillus acidophilus Grown in the Omega-6, -7 Riched Cyanobacteria Spirulina platensis.

Lactobacillus acidophilus is a probiotic commonly used in aquaculture to enhance the growth and immune system of aquatic species through the synthesis of various enzymes, and antimicrobial compounds like lactic acid. Traditional method of growing L. acidophilus involes using the De Man-Rogosa-Sharpe (MRS) medium. However, L. acidophilus belongs to a non-spore forming group, which make it vulnerable to stress conditions, especially during the usage process. Therefore, the present study aimed to improve the survival rate, antibacterial activity, and enrich the polyunsaturated fatty acids (PUFAs) content of L. acidophilus LB when cultured in an algae-supplemented medium, thus increasing its benefits in aquaculture applications. Using different algae biomass species as an alternative to MRS medium for the growth of L. acidophilus LB, the results showed that Spirulina platensis promoted the highest density of L. acidophilus LB. When grown in (S. platensis + glucose) medium, L. acidophilus LB produced the highest lactic acid concentration of 18.24 ± 2.43mg/mL and survived in extreme conditions such as 4% NaCl, pH 1.0-2.0, and 50ºC, and inhibited 99.82 ± 0.24% of Vibrio parahaemolyticus population after 2days of treatment. Additionally, it was observed that the PUFAs content, specifically omega-6, and -7, also increased in the fermentation mixture as compared to the control sample. These findings highlighted the potential of utilizing the cyanobacteria S. platensis as an alternative, eco-friendly growth substance for L. acidophilus LB to enhance its bioactivity and viability under extreme conditions.

Metabolomic Differences between Viable but Nonculturable and Recovered Lacticaseibacillus paracasei Zhang.

The fermentation process can be affected when the starter culture enters the viable but nonculturable (VBNC) state. Therefore, it is of interest to investigate how VBNC cells change physiologically. Lacticaseibacillus (L.) paracasei Zhang is both a probiotic and a starter strain. This study aimed to investigate the metabolomic differences between VBNC and recovered L. paracasei Zhang cells. First, L. paracasei Zhang was induced to enter the VBNC state by keeping the cells in a liquid de Man-Rogosa-Sharpe (MRS) medium at 4 °C for 220 days. Flow cytometry was used to sort the induced VBNC cells, and three different types of culture media (MRS medium, skim milk with 1% yeast extract, and skim milk) were used for cell resuscitation. Cell growth responses in the three types of recovery media suggested that the liquid MRS medium was the most effective in reversing the VBNC state in L. paracasei Zhang. Metabolomics analysis revealed 25 differential metabolites from five main metabolite classes (amino acid, carbohydrate, lipid, vitamin, and purine and pyrimidine). The levels of L-cysteine, L-alanine, L-lysine, and L-arginine notably increased in the revived cells, while cellulose, alginose, and guanine significantly decreased. This study confirmed that VBNC cells had an altered physiology.

Oral vaccination with recombinant Lactobacillus plantarum encoding Trichinella spiralis inorganic pyrophosphatase elicited a protective immunity in BALB/c mice.

BackgroundTrichinellosis is a serious zoonotic disease distributed around the world. It is needed to develop a safe, effective and feasible anti-Trichinella vaccine for prevention and control of trichinellosis. The aim of this study was to construct a recombinant Lactobacillus plantarum encoding Trichinella spiralis inorganic pyrophosphatase (TsPPase) and investigate its immune protective effects against T. spiralis infection.Methodology/Principal findingsThe growth of recombinant L. plantarum was not affected by TsPPase/pSIP409-pgsA′ plasmid, and the recombinant plasmid was inherited stably in bacteria. Western blot and immunofluorescence assay (IFA) indicated that the rTsPPase was expressed on the surface of recombinant L. plantarum. Oral vaccination with rTsPPase induced higher levels of specific serum IgG, IgG1, IgG2a and mucosal secretory IgA (sIgA) in BALB/c mice. ELISA analysis revealed that the levels of IFN-γ and IL-4 released from spleen, mesenteric lymph nodes and Peyer’s patches were evidently increased at 2–4 weeks following vaccination, compared to MRS (De Man, Rogosa, Sharpe) medium control group (P < 0.05). Immunization of mice with rTsPPase exhibited a 67.18, 54.78 and 51.91% reduction of intestinal infective larvae, adult worms and muscle larvae at 24 hours post infection (hpi), 6 days post infection (dpi) and 35 dpi, respectively (P < 0.05), and the larval molting and development was significantly inhibited by 45.45% at 24 hpi, compared to the MRS group.ConclusionsTsPPase plays a crucial role in T. spiralis molting and development, oral vaccination with rTsPPase induced a significant local mucosal sIgA response and systemic Th1/Th2 immune response, and immune protection against T. spiralis infection in BALB/c mice.

Formulation and optimization of alternative culture media for probiotic bacteria growth using tofu liquid waste

Probiotics from lactic acid bacteria (LAB) are widely used in the livestock industry to replace the use of Antibiotics Growth Promoters (AGPs). LAB is a culture starter that is widely used in fermented foods. LAB has the ability to adapt to different substrates, resulting in its wide use in the fermentation of various food products. MRS (De Man Rogosa Sharpe) medium is a growth medium for LAB, but for the industrial-scale requires a high cost, therefore innovation is needed to find alternative culture media using local raw material. Tofu Liquid Waste (TLW) can be used as a growth medium for probiotic bacteria because it still contains enough nutrients source for growth. This study aims to determine the formulation and optimization of culture media for LAB isolates using tofu liquid waste. Six Lab isolates from chickens gastrointestinal tract were used in experiments to determine the ability to grow on TLW culture media. The growth assays are conducted by inoculating LAB isolates in the culture media formulation that divided into 4 groups, consisting of medium A (TLW+molasses 1,5%+skim milk 5%), B (TLW+molasses 1,5%+skim milk 2,5%), C (TLW+molasses 3%+skim milk 5%), and D (TLW+molasses 3%+skim milk 2,5%). The best LAB isolate to grow on TLW medium was Lactobacillus paracasei. The best TLW modification medium for Lactobacillus paracasei growth is D media. Modified media consisting of TLW, molasses and skim milk can be used as an alternative medium for LAB growth.

Characterization and bioactivities of exopolysaccharide produced from probiotic Lactobacillus plantarum 47FE and Lactobacillus pentosus 68FE.

This investigation attempts to assess the exopolysaccharide (EPS) production from probiotic Lactobacilli isolated from Egyptian cheese products. Three Lactobacillus isolates (14FE, 47FE, and 68FE) were declared possible probiotic features. These isolates displayed neither hemolytic nor gelatinase activity. They were also susceptible to most antibiotics and confirmed utilizing 16S rRNA namely, Lactobacillus pentosus 14FE, Lactobacillus plantarum 47FE, and Lactobacillus pentosus 68FE with accession number MK616467, MK616469, and MK616468, respectively. All of them had the aptitude to produce EPS on the reconstructed Man Rogosa Sharpe medium (MRS). As a result, the three strains yielded high EPS production (4.15 ± 0.5–11.86 ± 0.1 g/L) after 48hr of incubation. The specific spectra of EPSs were obtained by FT-IR and 1H NMR analysis. All EPSs had glucose as a sole sugar constituent indicating they were glucan. The highest molecular weight (Mw, 104 kDa) was recorded with EPS68FE and the highest melting point was found with EPS47FE. Bioactivities indicated that the EPSs manifested potent antibacterial activity, and two of them (EPS47FE and EPS68FE) possessed a powerful anticoagulant and fibrinolytic activity. The EPSs (10 mg/mL) showed high DPPH radical of 54.50 ± 0.2–68.90 ± 0.3% and also emulsifying activity of 53.33 ± 0.5–83.33 ± 0.3% after 48hr. In conclusion, the EPS47FE, and EPS68FE produced from probiotic Lactobacilli had unique bioactivities with great potential in biomedicine, pharmaceutics, and food industries.

Probiotic BSH Activity and Anti-Obesity Potential of Lactobacillus plantarum Strain TCI378 Isolated from Korean Kimchi.

Lactobacillus (Lab.) is a human probiotic beneficial for the prevention and improvement of disease, yet properties of different Lab. strains are diverse. To obtain a Lab. strain that possesses greater potential against gastrointestinal dysfunction, we isolated Lactobacillus plantarum TCI378 (TCI378) from naturally fermented Korean kimchi. TCI378 has shown potential as probiotic since it can survive at pH 3.0 and in the presence of 0.3% bile acid. The bile salt hydrolase activity of TCI378 was shown by formation of opaque granular white colonies on solid de Man Rogosa Sharpe (MRS) medium supplemented with taurodeoxycholic acid, and its cholesterol-lowering ability in MRS medium supplemented with cholesterol. The metabolites of TCI378 from liquid culture in MRS medium prevented emulsification of bile salts. Moreover, both the metabolites of TCI378 and the dead bacteria reduced oil droplet accumulation in 3T3-L1, as detected by Oil red O staining. The expressions of adipocyte-specific genes perilipin 1 and glucose transporter type 4 were suppressed by the metabolites of TCI378, indicating TCI378 may have anti-obesity effects in adipocytes. These in vitro data show the potential of the prophylactic applications of TCI378 and its metabolites for reducing fat and lowering cholesterol.

PENGARUH PENGGUNAAN MADU TERHADAP NILAI pH, SINERESIS, DAN TOTAL BAKTERI ASAM LAKTAT YOGHURT SINBIOTIK

THE EFFECT OF THE ADDITION OF HONEY TO THE PH VALUE, SYNERESIS AND TOTAL LACTIC ACID BACTERIA OF SINBIOTIK YOGURT. This study was conducted to determine whether honey gives an influence on the pH value, syneresis and LAB of synbiotic yogurt. In this study, the main ingredients used were 5 liters UHT milk, Skim milk 400 g, honey 240 mL, Lactobacillus acidophillus bacteria, Streptococcus thermophilus and Lactobacillus bulgaricus, aqudes, MRS Media (Man Rogosa Sharpe Medium). Equipment used during the study included autoclave, pH meter, Erlenmeyer, test tube, pipette, thermometer, analytical scale, petri dishe, desiccator, blender, oven, incubator, micro pipette, burette, spritus lamp, goblet, refrigerator. This research was carried out on January 7 2019 until March 12 2019 at the Laboratory of Animal Product Technology Faculty of Animal Husbandry, Sam Ratulangi University, Manado. The experimental design used in this study was a Completely Randomized Design (CRD) method with treatments 5 and 4 replications. The variables analyzed in this study are pH, Sinereis and Total LAB. The data obtained were analyzed using ANOVA, there were significant differences between the treatments followed by the BNJ test. The results of this study indicate that the treatments of P0(0%), P1(3%), P2(6%), P3(9%) and P4(12%) have a very significant effect (P &lt;0.01) on the pH value, Sineresis and Total LAB. Based on the results and discussion that the use of honey by 12% can increase the value and produce the best pH, syneresis and total lactic acid bacteria in synbiotic yogurt.Keywords: Sinbiotic Yogurt, Honey, pH, Sinresis, LAB.

Antibacterial Effect of Essential Oils against Spoilage Bacteria from Vacuum-Packed Cooked Cured Sausages

Nonfermented sausages, which have a pH of around 6.0, a low salt concentration, and high moisture with a water activity higher than 0.95, are highly perishable. In this study, culture-dependent techniques and 16S rDNA approaches were used to identify the presumptive spoilage lactic acid bacteria (LAB) in sliced vacuum-packed cooked sausage during storage at 4°C. The antibacterial properties of essential oils (EOs) from the medicinal plants Carum carvi, Cinnamomum zeylanicum, Curcuma longa, Citrus medica, and Eugenia caryophyllata against isolated LAB were also investigated. A total of 106 colonies were obtained on de Man Rogosa Sharpe medium after storage of sausages samples, and 16 isolates were identified from conventional morphological analysis of the bacterial populations. DNA extraction and 16S rDNA analysis indicated that Lactobacillus curvatus, Weissella viridescens, Leuconostoc mesenteroides, Enterococcus faecium, Lactobacillus reuteri, Lactobacillus dextrinicus, Lactobacillus sakei, and Pediococcus dextrinicus were the main spoilage LAB. The antibacterial properties of EOs against isolated LAB were indicated by inhibition zones on culture plates of 7.8 to 31 mm, depending on the susceptibility of the tested LAB strain. The MICs and MBCs of five EOs were determined. The most effective EO against the LAB was C. zeylanicum followed by C. carvi and C. medica, and the least effective EO was C. longa. The EO from C. zeylanicum had the highest antimicrobial activity (lowest MICs) against LAB, with EO MICs of 4.66 to 5.33 μL/mL. The most susceptible isolate was L. mesenteroides, with a MIC of 4.66 μL/mL for the C. zeylanicum EO. These data indicate that the EO from C. zeylanicum could be used as a natural preservative for vacuum-packed emulsion-type sausage.

Rapid genus identification of selected lactic acid bacteria isolated from Mugil cephalis and Oreochromis niloticus organs using MALDI-TOF

Lactic acid bacteria (LAB) are traditionally used in food and feed bio-industries as they have health-promoting probiotic effect for their host and currently considered safe for human and animal consumption. Recently, we isolated 177 strains from freshwater fishes of dams of Tunisia exhibiting antimicrobial activities against various food-borne pathogens and generated a laboratory biobank to be characterized. Herein, we investigated whether MALDI-TOF could assist rapid identification of LAB genus. First, a lactic microflora-selective Man Rogosa Sharpe medium was used. Isolates were further screened according to the antimicrobial activity, using well-difusion agar. In total, four major genera have been well identified and species frequency has been estimated (74% Enterococcus, 24% Leuconostoc, 3% Lactococcus, and 2% Vagococcus). Eighteen isolates was further analyzed using MALDI-TOF. Comparative analysis of spectral fingerprints to six referenced MALDI-TOF fingerprints was carried out from the recently developed USC library ( www.spectrabank.org ). The intra- and inter-specific phyloproteomic relationships among strains were compared to available phylogenetic data based on 16S rDNA genes. This study showed that MALDI-TOF MS is a potent and reliable rapid method for both discrimination and identification of LABs. This highlights the insight of proteomic approach into the screening of food-derived beneficial microorganisms.

Evaluation of Petrifilm Lactic Acid Bacteria Plates for Counting Lactic Acid Bacteria in Food

Although lactic acid bacteria (LAB) are used widely as starter cultures in the production of fermented foods, they are also responsible for food decay and deterioration. The undesirable growth of LAB in food causes spoilage, discoloration, and slime formation. Because of these adverse effects, food companies test for the presence of LAB in production areas and processed foods and consistently monitor the behavior of these bacteria. The 3M Petrifilm LAB Count Plates have recently been launched as a time-saving and simple-to-use plate designed for detecting and quantifying LAB. This study compares the abilities of Petrifilm LAB Count Plates and the de Man Rogosa Sharpe (MRS) agar medium to determine the LAB count in a variety of foods and swab samples collected from a food production area. Bacterial strains isolated from Petrifilm LAB Count Plates were identified by 16S rDNA sequence analysis to confirm the specificity of these plates for LAB. The results showed no significant difference in bacterial counts measured by using Petrifilm LAB Count Plates and MRS medium. Furthermore, all colonies growing on Petrifilm LAB Count Plates were confirmed to be LAB, while yeast colonies also formed in MRS medium. Petrifilm LAB Count Plates eliminated the plate preparation and plate inoculation steps, and the cultures could be started as soon as a diluted food sample was available. Food companies are required to establish quality controls and perform tests to check the quality of food products; the use of Petrifilm LAB Count Plates can simplify this testing process for food companies.

Antifungal Attributes of Lactobacillus plantarum MYS6 against Fumonisin Producing Fusarium proliferatum Associated with Poultry Feeds.

Fumonisins, being common in occurrence in maize-based feeds, pose a great threat to animal and human health. The present study is aimed at determining the antifungal activity of Lactobacillus plantarum MYS6 against a fumonisin producing fungus, Fusarium proliferatum MYS9. The isolate was subjected to standard tests for determining its probiotic attributes and antifungal properties. L. plantarum MYS6 thrived well at pH 3.0 and 6.0, and exhibited strong resistance up to 3% bile. The isolate showed a high degree of cell surface hydrophobicity corresponding to its strong adhesion to chicken crop epithelial cells. Co-inoculation with the fungus on modified de Man Rogosa Sharpe medium revealed the inhibitory effect of L. plantarum MYS6 on fungal growth and biomass. Observation using scanning electron microscopy showed distortion of hyphal structures, swollen tips and disrupted conidia. Conidia germination inhibition assay restrained germination and showed deformed hyphae. The bioprotective feature of the isolate was evident by the inhibition of fungal development in maize-kernel treated with the cell free supernatant of L. plantarum MYS6. Both the isolate and its extracellular metabolites lowered fumonisin content in feed model up to 0.505 mg/Kg of feed and 0.3125 mg/Kg of feed respectively when compared to the level of 0.870 mg/Kg of feed in control. The major antifungal compounds produced by the isolate were 10-Octadecenoic acid, methyl ester; palmitic acid, methyl ester; heptadecanoic acid, 16-methyl ester; stearic acid and lauric acid. L. plantarum MYS6 reduced 61.7% of fumonisin possibly by a binding mechanism. These findings suggest the application of L. plantarum MYS6 as an efficient probiotic additive and biocontrol agent in feed used in poultry industry. Additionally, the antifungal metabolites pose a conspicuous inhibition of Fusarium growth and fumonisin production.

Isolation and characterization of dextran produced by Leuconostoc citreum NM105 from manchurian sauerkraut

A water-soluble exopolysaccharide (EPS) was produced by Leuconostoc ctireum NM105 from homemade manchurian sauerkraut. After culturing the strain in Man–Rogosa–Sharpe medium containing 5% sucrose at 25°C for 48h, the EPS was purified and a yield of 23.5g/L was achieved. The EPS consisted exclusively of glucose and the weight-average molecular weight was 1.01×108Da. The structural characterization of the purified EPS determined by FT-IR, 1H, 13C and two-dimensional NMR spectroscopy demonstrated that the glucan contained α-(1→6)-linked d-glucopyranose units, 2,6-linked d-glucopyranose units and terminal α-d-glucopyranose units at a ratio of 1:1:1. The microstructure of the dried dextran appeared a sheet-like smooth glittering and highly branched surface. The NM105 dextran showed high water solubility and excellent water retention. All the results suggested that the highly α-(1→2) branched dextran might have the potential to serve as valuable polymers applied in foods, cosmetics and other fields.

Analysis of biofilm formation by intestinal lactobacilli.

In this study, the biofilm-forming potential of intestinal Lactobacillus reuteri strains under different culture conditions was characterized by microtiter plate biofilm assays. Moreover, the spatial organization of exogenously applied L. reuteri L2/6 (a pig isolate) at specific locations in gastrointestinal tract of monoassociated mice was investigated by fluorescence in situ hybridization. We did not detect biofilm formation by tested strains in nutrient-rich de Man-Rogosa-Sharpe (MRS) medium. On the contrary, a highly positive biofilm formation was observed in medium with lower accessibility to the carbon sources and lack of salts. The results obtained confirmed the significant role of Tween 80 and the quantity and nature of the sugars in the growth medium in biofilm formation. The omission of Tween 80 in MRS medium favored the formation of biofilm. Abundant biofilm formation was detected in the presence of lactose, galactose, and glucose. However, a gradual increase in sugar concentration triggered a significant decrease in biofilm formation. In addition, conditions related to the gastrointestinal environment, such as low pH and the presence of bile and mucins, highly modulated biofilm production. This effect seems to be dependent on the specificity and properties of the medium used for cultivation. From the evidence provided by this study we conclude that the biofilm formation capacity of L. reuteri is strongly dependent on the environmental factors and culture medium used.

Cellular fatty acid composition and exopolysaccharide contribute to bile tolerance inLactobacillus brevisstrains isolated from fermented Japanese pickles

Bile tolerance is a fundamental ability of probiotic bacteria. We examined this property in 56 Lactobacillus brevis strains isolated from Japanese pickles and also evaluated cellular fatty acid composition and cell-bound exopolysaccharide (EPS-b) production. The bile tolerance of these strains was significantly lower in modified de Man - Rogosa - Sharpe (MRS) medium (without Tween 80 or sodium acetate) than in standard MRS medium. Aggregating strains showed significantly higher bile tolerance than nonaggregating strains in MRS medium, but there was no significant difference in the modified MRS media. The relative octadecenoic acid (C18:1) content of the 3 most tolerant aggregating and nonaggregating strains was significantly higher when bile was added to MRS. In MRS without Tween 80, the relative C18:1 content was only marginally affected by addition of bile. In MRS without sodium acetate, only the 3 most tolerant nonaggregating strains increased their relative C18:1 content in the presence of bile. Meanwhile, culture in MRS without sodium acetate reduced EPS-b production in aggregating strains. In conclusion, both EPS-b and cellular fatty acid composition play important roles in bile tolerance of pickle-derived L. brevis.

Optimisation for high cell density cultivation of Lactobacillus salivarius BBE 09-18 with response surface methodology

Based on the nutritional and physiological requirements of lactic acid bacteria (LAB), the effects of different carbon sources, nitrogen sources, buffer salts, microelements and growth factors on the growth of Lactobacillus salivarius BBE 09-18 (L. salivarius BBE 09-18) were investigated, among which three key factors were determined and optimised by response surface methodology. Estimated optimal conditions of the factors for the growth of L. salivarius BBE 09-18 determined. After cultivated in this optimised medium for 18 h at 37 °C, the viable cell count for L. salivarius BBE 09-18 was 5.94 × 109 cfu mL−1, which was about 3 times higher than that obtained in standard Man Rogosa Sharpe medium. This study will lay a solid foundation for the high cell density cultivation of L. salivarius BBE 09-18 to circumvent bottlenecks encountered in the production of LAB starters and probiotic ingredients in the field of dairy.

Effect of isomaltooligosaccharide and gentiooligosaccharide on the growth and fatty acid profile of Lactobacillus plantarum

Background: Lactobacillus sp. are probiotic microorganisms, and some of them are able to produce conjugated linoleic acid (CLA) via the bio-hydrogenation of linoleic acid (LA). Both CLA and LA are polyunsaturated fatty acids commonly used in the prevention and control of cardiovascular disease, high cholesterol, and cancer, among other ailments. The carbon source is one variable that can affect the growth and characteristics of these bacteria. Molecules called prebiotics are known to benefit human health by stimulating the growth and activity of probiotic bacteria present in the intestinal microflora. The aim of this study was to evaluate how different oligosaccharides affect the growth and fatty acid profile of Lactobacillus plantarum (NRRL - B4496). L. plantarum cultivation was performed in Man-Rogosa-Sharpe (MRS) medium, and the original carbon source (glucose) in this medium was partially or totally replaced by an oligosaccharide (isomaltooligosaccharide (IMO) or gentiooligosaccharide (GTO)). Then, the biomass concentration and fatty acid profile were determined using spectrophotometry and gas chromatography, respectively. Results: When 50% of the glucose in the MRS medium was replaced with IMO, the maximum growth was 2.6 g/L at 37ºC. Under the same culture conditions, the incorporation of GTO only produced 2 g/L of biomass. At 45ºC, the growth of the bacterial culture was lower than that observed at 37ºC, reaching only 0.4 g/L. When cultivated at 37ºC in a mixture of glucose and GTO (1:1), CLA (34%, c9t11) was obtained from cells of L. plantarum . However, when the cultivation was performed at 45ºC, CLA was not obtained. When IMO was used, differences in CLA content were not observed between L. plantarum cultivated with glucose or with IMO present; however, vaccenic acid was produced. Conclusions: Lactobacillus plantarum grow well when a mixture of IMO and glucose is used as the carbon source. However, this mixture does not improve the CLA content, most likely due to high enzymatic activity that promotes the conversion of CLA to vaccenic acid. Additionally, GTO is likely less readily metabolized by this strain. Thus, the enzymatic activity is likely lower and less CLA is converted to vaccenic acid, resulting in an accumulation of CLA.

Antifungal Hydroxy Fatty Acids Produced during Sourdough Fermentation: Microbial and Enzymatic Pathways, and Antifungal Activity in Bread

Lactobacilli convert linoleic acid to hydroxy fatty acids; however, this conversion has not been demonstrated in food fermentations and it remains unknown whether hydroxy fatty acids produced by lactobacilli have antifungal activity. This study aimed to determine whether lactobacilli convert linoleic acid to metabolites with antifungal activity and to assess whether this conversion can be employed to delay fungal growth on bread. Aqueous and organic extracts from seven strains of lactobacilli grown in modified De Man Rogosa Sharpe medium or sourdough were assayed for antifungal activity. Lactobacillus hammesii exhibited increased antifungal activity upon the addition of linoleic acid as a substrate. Bioassay-guided fractionation attributed the antifungal activity of L. hammesii to a monohydroxy C(18:1) fatty acid. Comparison of its antifungal activity to those of other hydroxy fatty acids revealed that the monohydroxy fraction from L. hammesii and coriolic (13-hydroxy-9,11-octadecadienoic) acid were the most active, with MICs of 0.1 to 0.7 g liter(-1). Ricinoleic (12-hydroxy-9-octadecenoic) acid was active at a MIC of 2.4 g liter(-1). L. hammesii accumulated the monohydroxy C(18:1) fatty acid in sourdough to a concentration of 0.73 ± 0.03 g liter(-1) (mean ± standard deviation). Generation of hydroxy fatty acids in sourdough also occurred through enzymatic oxidation of linoleic acid to coriolic acid. The use of 20% sourdough fermented with L. hammesii or the use of 0.15% coriolic acid in bread making increased the mold-free shelf life by 2 to 3 days or from 2 to more than 6 days, respectively. In conclusion, L. hammesii converts linoleic acid in sourdough and the resulting monohydroxy octadecenoic acid exerts antifungal activity in bread.

Production of bacteriocin by Leuconostoc mesenteroides 406 isolated from Mongolian fermented mare's milk, airag

The purification and characterization of a bacteriocin produced by Leuconostoc mesenteroides strain 406 that was isolated from traditional Mongolian fermented mare's milk, airag, were carried out. Leuconostoc mesenteroides strain 406 was identified on the basis of its morphological and biochemical characteristics and carbohydrate fermentation profile and by API 50 CH kit and 16S ribosomal DNA analyses. The neutral-pH cell-free supernatant of this bacterium inhibited the growth of several lactic acid bacteria and food spoilage and pathogenic organisms, including Listeria monocytogenes and Clostridium botulinum. The bacteriocin was heat-stable and not sensitive to acid and alkaline conditions, but was sensitive to several proteolytic enzymes such as pepsin, pronase E, proteinase K, trypsin, and α-chymotrypsin, but not catalase. Optimum bacteriocin production (4000 activity units/mL) was achieved when the strain was cultured at 25°C for 24-36 h in Man Rogosa Sharpe medium. The bacteriocin was partially purified by ammonium sulfate precipitation (80% saturation), dialysis (cut-off MW: 1000), and gel filtration chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the bacteriocin had a molecular weight of approximately 3.3 kDa. To our knowledge, this is the first report of the isolation of a bacteriocin-producing Leuconostoc strain from airag. An application to fermented milks would be desired.

Rapid, Simple, and Specific Cultivation-Based Method for Detection of Pectinatus spp. in Brewery Samples

A modified de Man–Rogosa–Sharpe (MRS) medium suitable for easy, fast, and specific detection of beer-spoilage bacteria Pectinatus spp. from beer and brewery swab samples was developed. It contains readily commercially available MRS broth, cysteine hydrochloride, and sodium thioglycolate as compounds lowering the redox potential of the medium, Tetra (a mixture of tetrahydroiso-α-acids) and 2-phenylethanol as the specificity-ensuring components, and bacteriological agar, which prevents medium oxidation during sample manipulation and transport. Tests with beer and brewery isolates of Pectinatus frisingensis, P. cerevisiiphilus, P. haikarae, Lactobacillus brevis, L. paracasei, L. plantarum, Lactococcus lactis, Pediococcus damnosus, and brewery strains of Saccharomyces pastorianus and S. cerevisiae showed that the medium does not inhibit the growth of Pectinatus spp. yet suppresses the growth of other beer- and brewery-contaminating microorganisms, which, thus, do not interfere with Pectinatus determination. The characteristic and easy-to-detect snake-like motile cells of Pectinatus spp. appear after a 24-to-48 hr cultivation of samples in MRS medium with Tetra.

Comparison of natural whey starters for Grana Padano cheese using sunray plots

Twenty-one natural whey starters, collected from dairy factories located in six provinces of the Grana Padano production area, were characterized. Basic techniques, such as acidity evaluation and microbial plate count, together with more complex methods such as the Live/Dead® BacLight™ bacterial viability kit, have been used. Seven parameters, including pH, Soxhlet Henkel degrees, microbial plate count in Man Rogosa Sharpe medium and Whey Agar medium, together with count of total, viable and non-viable cells, have been adopted to produce sunray plots. One plot for each natural whey starter sample was obtained by characterizing the status of the microbial culture and compared with three natural whey starters prepared in the laboratory. In this way, a sunray trace is suggested to define the traits of a good natural whey starter. Another multivariate technique, principal component analysis, was applied, and it should be possible to conclude that, for this particular dataset composed of 24 objects and 7 variables, PCA allowed the highlighting of the good and bad samples, while sunray plots, even if remaining only a descriptive and explorative analysis, allowed the better visualizing of the differences among all the samples.