Proteose Peptone Research Articles

Increasing plasmid-based DNA vaccine construct (16 kb pSVK-HBVA) production in Escherichia coli XL10-Gold through optimization of media component

At present, there are production processes to produce protein by Escherichia coli (E. coli) fermentation. Research on the design and optimization of the plasmid fermentation medium, however, is less advanced. The fermentation medium that is optimized for plasmid DNA production is different from the medium that is optimized for protein production. So, establishing a scientific and rational method to optimize the fermentation medium used for plasmid production is very important. Previously, our laboratory developed a novel therapeutic DNA vaccine (named pSVK-HBVA) for hepatitis B based on the alphavirus replicon, and found that E. coli XL10-Gold was the optimal host strain for the production of plasmid pSVK-HBVA. The aim of this study was to establish a scientific and rational method to optimize the fermentation medium used for plasmid production, and investigate the effect of growth medium composition on the production of plasmid pSVK-HBVA harboured in E. coli XL10-Gold, as well as to optimize the medium composition.The one-factor-at-a-time experiments demonstrated that Luria-Bertani (LB) was the optimal basic medium. The optimal carbon source and nitrogen source were glycerol and home-made proteose peptone, respectively. Based on the Plackett–Burman (PB) design, proteose peptone, glycerol and NH4Cl were identified as the significant variables, which were further optimized by the steepest ascent (descent) method and central composite design. Growth medium optimization in 500-mL shake flasks by response surface methodology resulted in a maximum volumetric yield of 13.61 mg/L, which was approximately 2.5 times higher than that obtained from the basic medium (LB).

Thermal andPhysical Properties of Biofield Treated Bile Salt and Proteose Peptone

Bile salt (BS) and proteose peptone (PP) are important biomacromolecules being produced inside the human body. The objective of this study was to investigate the influence of biofield treatment on physicochemical properties of BS and PP. The study was performed in two groups (control and treated). The control group remained as untreated, and biofield treatment was given to treated group. The control and treated BS and PP samples were characterized by particle size analyzer (PSA), Brunauer-Emmett-Teller (BET) analysis, differential scanning calorimetry (DSC), x-ray diffraction (XRD), and thermogravimetric analysis (TGA). PSA results showed increase in particle size (d50 and d99) of both treated BS and PP as compared to control. Surface area analysis showed minimal decrease by 1.59%, in surface area of treated BS as compared to control. However, the treated PP showed increase (8%) in surface area as compared to control. DSC characterization showed increase in melting temperature of treated BS as compared to control. Whereas, DSC thermogram of treated PP showed decrease in melting temperature with respect to control. Moreover, the DSC of control and treated PP showed presence of exothermic peaks which were possibly due to protein aggregation. The treated PP showed higher exothermic transition temperature as compared to control. XRD analysis revealed slight reduction in crystalline nature of BS as compared to control. On the other hand, XRD data of control and treated PP showed an amorphous nature. TGA analysis of treated BS showed maximum thermal decomposition temperature at 22°C which was higher as compared to control sample (106°C). This could be due to biofield treatment which may enhance the thermal stability of treated BS with respect to control. However, the TGA thermogram of treated PP showed decrease in maximum thermal stability as compared to control. The overall results showed that biofield treatment has significantly altered the physical and thermal properties of BS and PP.

Lactobacillus gasseri requires peptides, not proteins or free amino acids, for growth in milk

Lactobacillus gasseri is a widespread commensal lactic acid bacterium inhabiting human mucosal niches and has many beneficial effects as a probiotic. However, L. gasseri is difficult to grow in milk, which hurts usability for the food industry. It had been previously reported that supplementation with yeast extract or proteose peptone, including peptides, enables L. gasseri to grow well in milk. In this study, our objective was to confirm peptide requirement of L. gasseri and evaluate efficacy of peptide release by enzymatic proteolysis on growth of L. gassei in milk. Three strains of L. gasseri did not grow well in modified DeMan, Rogosa, Sharpe broth without any nitrogen sources (MRS-N), but addition of a casein-derived peptide mixture, tryptone, promoted growth. In contrast, little effect was observed after adding casein or a casein-derived amino acid mixture, casamino acids. These results indicate that L. gasseri requires peptides, not proteins or free amino acids, among milk-derived nitrogen sources for growth. Lactobacillus gasseri JCM 1131T hardly had growth capacity in 6kinds of milk-based media: bovine milk, human milk, skim milk, cheese whey, modified MRS-N (MRSL-N) supplemented with acid whey, and MRSL-N supplemented with casein. Moreover, treatment with digestive proteases, particularly pepsin, to release peptides made it grow well in each milk-based medium. The pepsin treatment was the most effective for growth of strain JCM 1131T in skim milk among the tested food-grade proteases such as trypsin, α-chymotrypsin, calf rennet, ficin, bromelain, and papain. As well as strain JCM 1131T, pepsinolysis of milk improved growth of other L. gasseri strains and some strains of enteric lactobacilli such as Lactobacillus crispatus, Lactobacillus gallinarum, Lactobacillus johnsonii, and Lactobacillus reuteri. These results suggest that some relatives of L. gasseri also use peptides as desirable nitrogen sources, and that milk may be a good supplier of nutritious peptides to enteric lactobacilli including L. gasseri after peptic digestion in the gastrointestinal tract. This is the first report showing peptide requirement of L. gasseri and efficacy of pepsinolysis on the growth of L. gasseri and its relatives in milk. This study would contribute to increasing usability of L. gasseri and its relatives as probiotics in dairy foods.

Dependency of the fatty acid composition of Euglena gracilis on growth phase and culture conditions

Usually, the fatty acid (FA) composition of lipids from microalgae is determined using samples taken at a single time point only, often without considering the medium composition and cultivation conditions. Therefore, the results only represent the FA composition of cells in a certain growth phase. Furthermore, they may misrepresent the capability of the organism to produce certain FA or lipid mixtures. In this study, 22 FA were analysed quantitatively during the cultivation of Euglena gracilis under different cultivation modes and conditions. For cell growth, various media compositions for heterotrophic and photoheterotrophic conditions were used. Results of extensive FA analysis allowed the determination of appropriate cultivation conditions and durations for yielding lipid mixtures with optimal composition, e.g. for the production of biodiesel or functional food. Drastic differences in the ratio between n3- and n6-polyunsaturated fatty acid (PUFA) ranging from 0.04 to 1.81 were detected. This effect was strongly influenced by the cultivation mode. In addition, media with higher nitrogen concentration resulted in a higher n3/n6-PUFA-ratio as well as improved specific growth rates for all analysed combinations of glucose and nitrogen concentrations. Furthermore, it was demonstrated that the inexpensive proteose peptone medium is ideal for lipid production by E. gracilis. This work provides valuable tools to optimise yield, productivity and n3/n6-PUFA ratio concerning the cultivation of E. gracilis as well as potentially other microalgae in general.

First Report of Bacterial Stalk Rot of Maize Caused by Dickeya zeae in Mexico.

A bacterial disease of maize, bacterial stalk and top rot, was found in the state of Morelos in February 2011, and in the state of Puebla in July 2013, Mexico. In both cases, the incidence of diseased plants was lower than 0.5%. The typical symptoms were a soft rot and darkening of the tissues affecting the stalk and the top of the plant, causing breaking of the stalk. The lesions progressed from the top to below nodes, leaf sheaths and blades, and rotten tissues emitted an unpleasant odor. Eleven diseased plants were collected, and bacterial colonies were isolated from fragments detached from the edges of symptomatic tissues after sterilization with a 0.5% solution of NaClO for 30 s, rinsing three times in sterile water. The sterilized fragments were macerated in drops of distilled sterile water for 10 min and the extract was streaked on King's medium B (agar 15 g, distilled water 1,000 ml, proteose peptone 20 g, K2HPO4 1.5 g, MgSO4·7H2O 1.5 g, glycerol 10 ml). Eight representative strains from Morelos and five from Puebla were selected for identification. All strains were gram-negative, grew at 37°C, showed pectynolitic activity on potato tubers, were positive for indole production, utilized arabinose, galactose, glucose, glycerol, lactose, mannose, melibiose, rafinose, ribose, and sucrose but did not produce acid from arabitol, adonitol, and keto-methyl-glucoside (3,4). Pathogenicity tests were conducted with each strain by inoculating with a syringe four 25-day-old maize seedlings with 107 CFU ml-1 bacterial cells in the leaf collar. Plants were incubated in the greenhouse at 30°C during the day and 24°C during the night with a 12-h photoperiod, and relative humidity of 93%. The reference strains Erwinia chrysanthemi pv zeae ATTC29942 and Dickeya zeae CFBP 2052 were used as positive controls in laboratory and greenhouses tests. Sterile water was used as negative control. Two days after inoculation, soft stalk rot symptoms developed that were identical to those observed in the field. No symptoms were observed on the negative controls. Diagnostic amplification of DNA by conventional PCR was carried out and yielded the expected amplicon size of 420 bp of the Dickeya-specific pel gene with the ADE primers set (2). PCR was used to amplify the 16S rRNA gene with the universal primers 27f and 1495r (5) for molecular identification of the 13 strains (GenBank Accession Nos. KJ438941, KJ438942, KJ438943, KJ438944, KJ438945, KJ438946, KJ438947, KJ438948, KJ438949, KJ438950, KJ438951, KJ438952, and KJ438953). The strains D. zeae CFBP 2052 and E. chrysanthemi pv. zeae ATCC 29942 were sequenced as positive controls. A BLAST search with the 13 16S rRNA gene sequences of 1.4 kb were 99% identical to the sequence of D. zeae CFBP 2052 (NR_041923). D. zeae can be a major disease of maize in tropical and subtropical countries. It is particularly severe under conditions of high temperature and high humidity, but it occurs sporadically. Control of the vector, Chilo partellus, can aid disease management (1). To our knowledge, this is the first report of D. zeae causing maize stalk rot in Mexico.

Microaerophilic degradation of sulphonated azo dye – Reactive Red 195 by bacterial consortium AR1 through co-metabolism

The textile and dye industries are considered as one of the foremost sectors that pollutes environment. Technologies employing biological methods showed promising approach to remediate sites polluted with dye and dye intermediates. Bacterial consortium AR1 developed through culture enrichment method was comprised of four distinct bacterial strains. The synergistic metabolic activities of AR1 led to complete decolourization of monoazo dye Reactive Red 195 within 14 h under microaerophilic environment. The co-metabolic decolourization of Reactive Red 195 by consortium, in presence of maltose and proteose peptone (0.1%, w/v, each) in minimal medium, easily reduced Reactive Red 195 (100 mg/L) for five consecutive cycles without any replenishment of nutrient. The maximum decolourization was observed at pH 8.0 and 40 °C. The consortium was acclimatized to decolourize Reactive Red 195 at higher concentration (2000 mg/L) even under high salt concentration (1 M NaCl). Consortium exhibited broad substrate specificity where it decolourized 15 structurally different dyes and more than 50% decolourization was observed in a medium containing mixture of dyes. The degradation products analyzed using FTIR, HPTLC and 1H NMR revealed the formation of 2-amino-naphthalene, 1-amino-benzene and 1-nitro-benzene. Thus the ability of bacterial consortium for simultaneous decolourization and degradation of azo compounds signifies its potential application in dye remediation.

Production of ��- and ��-Galactosidases from Bifidobacterium longum subsp. longum RD47

Approximately 50% of people in the world experience abdominal flatulence after the intake of foods containing galactosides such as lactose or soybean oligosaccharides. The galactoside hydrolyzing enzymes of α- and β-galactosidases have been shown to reduce the levels of galactosides in both the food matrix and the human gastrointestinal tract. This study aimed to optimize the production of α- and β-galactosidases of Bifidobacterium longum subsp. longum RD47 with a basal medium containing whey and corn steep liquor. The activities of both enzymes were determined after culturing at 37°C at pH 6.0 for 30 h. The optimal production of α- and β-galactosidases was obtained with soybean oligosaccharides as a carbon source and proteose peptone no. 3 as a nitrogen source. The optimum pH for both α- and β-galactosidases was 6.0. The optimum temperatures were 35°C for α-galactosidase and 37°C for β- galactosidase. They showed temperature stability up to 37°C . At a 1 mM concentration of metal ions, CuSO4 inhibited the activities of α- and β-galactosidases by 35% and 50%, respectively. On the basis of the results obtained in this study, B. longum RD47 may be used for the production of α- and β-galactosidases, which may reduce the levels of flatulence factors.

Orthogonal array deciphering MRS medium requirements for isolated Lactobacillus rhamnosus ZY with cell properties characterization

Lactobacillus rhamnosus is a well-known lactic acid bacterium (LAB), but a new ZY strain was isolated for the first time from commercial probiotic powder recently. Although many studies have focused on developing cost-effective media for the production of LAB, the de Man, Rogosa and Sharpe (MRS) medium is still the most common medium for bioprocesses. The aim of the current study is to decipher the composition of MRS based on a statistical approach, which will allow a higher biomass of Lactobacillus to be obtained. In Taguchi's approach, an L27 orthogonal array was adopted to evaluate the significance of 10 ingredients in MRS, in which the effects of the components were ranked according to their effect on biomass at OD600 as dextrose > MnSO4·H2O > beef extract > CH3COONa > MgSO4 > yeast extract > proteose peptone > K2HPO4 > ammonium citrate > Tween 80. Although the individual trace elements of ammonium citrate, K2HPO4, CH3COONa and MgSO4 in MRS had an insignificant influence on the biomass after statistical analysis, the total elimination of trace elements would predominantly affect the cell growth of Lactobacillus. Further characterization of the cell properties through attenuated total reflectance of Fourier transform infrared (ATR-FTIR) spectroscopy and protein identification via SDS-PAGE coupled with tandem mass spectrometry implied that dextrose as major carbon source in MRS played the most crucial role for L. rhamnosus production.

Escherichia coli Capsular Polysaccharide Synthesis, Antibiotic Susceptibility, and Red Blood Cell Agglutination

Background Escherichia coli is a normal component of the human intestinal flora, but it is also a pathogen particularly in women with urinary tract infections, cystitis, and kidney diseases. A new capsular polysaccharide (CPS)-synthesizing variant strain of E. coli was isolated from a culturing bacterial medium containing proteose peptone No. 3 glycerin salt in our previous study. In this study, we further isolated a new E. coli variant, which produces capsular polysaccharides (CEF-CPS), using cefazolin (CEF) and examined the pathogenic characteristics of this CEF-CPS strain. Methods Polysaccharides produced by CEF-treated E. coli were separated and purified using anion exchange resin and gel filtration column chromatographic methods. The red blood cell (RBC) agglutination assay and antibiotic susceptibility test were conducted, and serum bactericidal activity, antibiotic tolerance, and antibiotic uptake were also examined. Results (1) Variant strains had greater RBC hemagglutination ability than parental strains. (2) The CEF-CPS variant strain showed a two-fold increase compared to the parental strain. (3) Antibiotic resistance to CEF, ampicillin, and polymyxin B was increased four-fold in the CEF-CPS variant strain. (4) Bacterial cell counts in the parental strain incubated in a medium containing gentamicin were reduced significantly, near to the undetectable level, within 4 hours. By contrast, bacterial counts of the CEF-CPS strain displayed only 50% reduction compared to the original bacterial counts under the same culture environment. Conclusion E. coli derived from normal human intestinal flora generated a new variant strain along with the production of newly synthesized additional polysaccharides on the cell wall in the presence of CEF. Their productions can contribute to enhancing multiple-drug resistance and pathogenicity.

Phosphoproteomic Analysis of Protein Phosphorylation Networks in Tetrahymena thermophila, a Model Single-celled Organism

Tetrahymena thermophila is a widely used unicellular eukaryotic model organism in biological research and contains more than 1000 protein kinases and phosphatases with specificity for Ser/Thr/Tyr residues. However, only a few dozen phosphorylation sites in T. thermophila are known, presenting a major obstacle to further understanding of the regulatory roles of reversible phosphorylation in this organism. In this study, we used high-accuracy mass-spectrometry-based proteomics to conduct global and site-specific phosphoproteome profiling of T. thermophila. In total, 1384 phosphopeptides and 2238 phosphorylation sites from 1008 T. thermophila proteins were identified through the combined use of peptide prefractionation, TiO2 enrichment, and two-dimensional LC-MS/MS analysis. The identified phosphoproteins are implicated in the regulation of various biological processes such as transport, gene expression, and mRNA metabolic process. Moreover, integrated analysis of the T. thermophila phosphoproteome and gene network revealed the potential biological functions of many previously unannotated proteins and predicted some putative kinase-substrate pairs. Our data provide the first global survey of phosphorylation in T. thermophila using a phosphoproteomic approach and suggest a wide-ranging regulatory scope of this modification. The provided dataset is a valuable resource for the future understanding of signaling pathways in this important model organism.

Sweet Potatoes as a Basic Component in Developing a Medium for the Cultivation of Lactobacilli

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.

Survival and Growth of Tetrahymena thermophila in Media that are Conventionally Used for Piscine and Mammalian Cells

The transfer of Tetrahymena thermophila from normosmotic solutions (~20-80 mOsm/kg H(2)O) to hyperosmotic solutions (> 290 mOsm/kg H(2)O) was investigated. During the first 24 h of transfer from proteose peptone yeast extract (PPYE) to either 10 mM HEPES or PPYE with added NaCl to give ~300 mOsm/kg H(2)O, most ciliates died in HEPES but survived in PPYE. Supplementing hyperosmotic HEPES or PPYE with fetal bovine serum (FBS) enhanced survival. When ciliates were transferred from PPYE to a basal medium for vertebrate cells, L-15 (~320 mOsm/kg H(2)O), only a few survived the first 24 h but many survived when the starting cell density at transfer was high (100,000 cells/ml) or FBS was present. These results suggest that nutrients and/or osmolytes in either PPYE or FBS helped ciliates survive the switch to hyperosmotic solutions. FBS also stimulated T. thermophila growth in normosmotic HEPES and PPYE and in hyperosmotic L-15. In L-15 with 10% FBS, the ciliates proliferated for several months and could undergo phagocytosis and bacterivory. These cell culture systems and results can be used to explore how some Tetrahymena species function in hyperosmotic hosts and act as opportunistic pathogens of vertebrates.

Pyocyanin pigment assisting biosurfactant-mediated hydrocarbon emulsification

A plethora of Pseudomonas strains was checked for their biosurfactant and pigment-producing abilities in Bushnell-Haas (BH) medium and proteose peptone glucose ammonium salts (PPGAS) medium. Five strains from different origins produced only biosurfactant in BH medium but both biosurfactant and pyocyanin pigment in PPGAS medium. Biosurfactant and pyocyanin exhibited a peculiar correlation as the culture supernatants containing both components emulsified hydrocarbons more than the biosurfactant alone. Enhancement in emulsification also occurred by mixing pyocyanin from PPGAS medium and biosurfactant from BH medium. Prior reports indicated that pigments protect producer strains from certain environmental stresses. The interesting finding of this study of pyocyanin pigment enhancing biosurfactant-mediated hydrocarbon emulsification was independent of the source of biosurfactant isolation. The synergistic action of pigment and biosurfactant found may be a general phenomenon for other Pseudomonas strains producing both biosurfactant and pigment, thus helping them to survive in arid conditions. The pigment-aided emulsification may help in lowering the requirement of biosurfactive agents for remediation purposes, which will also be helpful economically as the biosurfactants have very low yields. The enhancement in emulsification by the coupling of pigment with biosurfactant can have a significant impact in the paint industry and sectors dealing in environmental remediation.

Role of whey proteins in combating geriatric disorders

AbstractAgeing in humans is usually accompanied by deterioration in physical fitness and increased susceptibility to disease, adding to the economic burden of the person concerned. Inadequate food intake, reduced desire to eat, decline in food digestion or absorption, compromise in nutritional metabolic pathways, poor dental hygiene or preponderance of chronic diseases, which are commonly found in the elderly, can lead to an increased risk of under‐nutrition. Adequate dietary nutrition has an undisputed role in healthy ageing. Among the various nutrients, proteins play an important role in geriatric health. This review emphasizes the nutritional aspects of milk‐based whey proteins and their role in tackling health problems in the geriatric population. Nutritionally rich whey protein constituents such as β‐lactoglobulin, α‐lactalbumin, bovine serum albumin, lactoferrin and proteose peptone have all been reported to have a plethora of functional roles in various biological processes and organ systems in geriatrics and thus help in the management of geriatric health problems through proper nutrition. © 2013 Society of Chemical Industry

Use of Cell Cultures to Study the Interactions of Ciliates with Fish

How the ciliates of fish can be cultured and be used to study ciliate/fish interactions are reviewed. The culturing of ciliates is currently done in basal solutions based on either freshwater, seawater, or bodily fluids of vertebrates. These are supplemented either with bacteria, fish cells, or organic matter, which can be defined or more commonly undefined, with proteose peptone being a prominent example. Among pathogenic ciliates, the most difficult to culture has been Ichthyophthirius multifiliis. To contrast, Cryptocaryon irritans caused a similar disease and has been maintained successfully in co-cultures with fish cells. Pathogenic scuticociliates and tetrahymenas are more amenable to culture, and can be grown axenically. These cultures have been used to study pathogenic mechanisms and to screen drugs for their potential chemotherapeutic value. Ciliates may act directly on fish to cause disease, but may also influence fish health indirectly through their interactions with other types of fish pathogens, for example bacteria and fungi. For example, in culture Tetrahymena spp. have been shown to phagocytose pathogenic bacteria, Yersinia ruckerii, and microsporidia, Glugea hertwigi, where ciliates are not linked to disease, very different ciliate/fish interactions are possible. For some fish larvae, free-living ciliates are a source of nutrients. Large-scale cultures of both freshwater and marine ciliates have been achieved and could be a source of feed for fish larvae in aquaculture. Finally, ciliates have the potential to feed on fish carcasses and in doing so make nutrients available to the ecosystem. In the future cell cultures should be invaluable in studying these and other possible relationships between fish and ciliates.

Potential of Photorhabdus temperata K122 bioinsecticide in protecting wheat flour against Ephestia kuehniella

The present study reports investigations on the insecticidal activity of the entomopathogenic bacterium Photorhabdus temperata K122 against the Mediterranean flour moth Ephestia kuehniella. Cultured in the optimized medium, P. temperata K122 cells aged 32 h exhibited 51% growth inhibition at a concentration of 9 × 108 cells/ml. However, culture must be prolonged up to 48 h incubation in the proteose peptone medium to reach only 28.6% inhibition. At the same concentration, no adult emergence was observed in the case of larvae feeding on wheat flour treated with the whole culture of P. temperata K122 after physical lysis. Interestingly, P. temperata K122 cells in the viable but non culturable (VBNC) state retained the same toxicity level as the culturable cells. At a high concentration of 12 × 108 cells/ml, 100% mortality of E. kuehniella larvae could be reached. Insect mortality is due to toxaemia as confirmed by the absence of Variants small colony (Vsm) or P. temperata colonies in E. kuehniella tissue. The investigation of the histopathological effect of P. temperata toxins on the gut of infected E. kuehniella larvae showed destruction of the gut epithelium, appearance of large cavities and cellular disintegration.

Low molecular mass peptides generated by hydrolysis of casein impair rennet coagulation of milk

Previously it was shown that a low molecular mass fraction isolated from the proteose–peptone preparation of milk, fraction E, inhibited milk coagulation. Here, the composition and molecular mass of fraction E, and its effect on milk clotting parameters, was investigated to better understand its mechanism of action. Fraction E comprised casein-derived peptides of 1–3 kDa rich in phosphorus residues. Fraction E content increased substantially in milk from glands infected with Escherichia coli and Streptococcus dysgalactiae, and during storage of the milk. However, the specific activity of fraction E on milk clotting parameters was the same whether sampled from healthy, infected or stored milk. The inhibitory effect was reversible on adding 0.75 mm CaCl2, suggesting that chelation of Ca by fraction E was involved in the inhibitory mechanism. However, only partial recovery was achieved and an excess of Ca was required, suggesting the involvement of additional pathways in the process.

Effect of Cameline Nisin isolated from Lactococcus lactis sub sp. lactis on<br>Staphylococcus aureus sp.

The camel milk differs from milk of other species by the presence of a powerful protector system, linked to relatively high levels of lysozyme, lactoperoxidase, lactoferrin, component-3 of proteose peptone (PP3), organic acid, hydrogen peroxide and bacteriocins produced by lactic acid bacteria. The study aims to estimate the part of a bacteriocin (type nisin) produced by a strain of Lactococcus lactis sub sp lactis isolated from camel milk, in this protective system and its antibacterial activity against a strain of Staphylococcus aureus isolated from a bovine milk sample. Optimize conditions for a nisin production, by the producing strain isolated and purified, was carried out, by glucose addition (1%) to the M17 medium. Antagonism tests by the disk method showed inhibition zones (IZ O ) from 6 to 8mm in diameter depending on the incubation time of the producing strain. Thus, for incubation periods of 18h, the production of camel nisin appeared to be maximum (IZ= O 8mm) with a minimum growth of Lactococcus lactis sub sp lactis (pH 6, 37). Optimum growth of camel Lactococcus lactis sub sp lactis strain (pH 6.17) and an optimum production of nisin (IZ= O 8mm) were registered for a 24 hours incubation period.

STATISTICAL OPTIMIZATION OF BACTERIOCIN PRODUCTION BYPEDIOCOCCUS ACIDILACTICIIN A SIMPLE FOOD-GRADE MEDIUM

Bacteriocins produced by lactic acid bacteria are attractive as food biopreservatives in place of chemical preservatives. Pediococcus acidilactici was found to produce bacteriocin that can inhibit bacterial and fungal food contaminants. Based on the conventional deMan, Rogosa and Sharpe (MRS) medium, simplified food-grade medium for bacteriocin production by the bacterium was developed containing casein peptone and dextrose for food application and scale-up of the bioprocess. Central composite rotatable design was used to study the main and interactive effects of medium components and fermentation parameters, i.e., temperature and pH on bacteriocin production by Pediococcus acidilactici. The optimized medium conditions with 97% desirability under the set criteria were: casein peptone 3.97%, dextrose 3.45% at pH = 7.0 and temperature 35C. Bacteriocin titer obtained from the optimized casein peptone and dextrose medium was comparable with MRS medium (538 AU/mL). Practical Applications Bacteriocins from lactic acid bacteria are of potential usefulness as natural substitutes for chemical food preservatives in the production of food with enhanced shelf-life. The bacteriocin obtained from Pediococcus acidilactici has a wide spectrum of activity against bacterial and fungal food pathogens. Usually, bacteriocins is obtained from deMan, Rogosa and Sharpe medium that contains nitrogen sources such as beef extract, yeast extract, proteose peptone and ammonium citrate that is not acceptable by the consumers. Keeping this in mind, we have developed a food-grade medium containing casein peptone and dextrose for food applications. Further casein peptone and dextrose concentrations along with fermentation parameters such as pH and temperature were optimized to give optimum yield of bacteriocins. So, the bacteriocin produced in the food-grade medium should be acceptable by the consumers as well as economical according to industrial point of view.

Proteolytic activation of proteose peptone component 3 by release of a C-terminal peptide with antibacterial properties

The milk protein proteose peptone component 3 (PP3, also known as lactophorin) is a small phosphoglycoprotein, which is exclusively expressed in the lactating mammary gland. A 23-residue synthetic peptide (lactophoricin, Lpcin S), corresponding to the C-terminal amphipathic α-helix of PP3, has previously been shown to permeabilize membranes and display antibacterial activity. Lactophorin readily undergoes proteolytic cleavage in milk and during dairy processing, and it has been suggested that PP3-derived peptides are part of milk's endogenous defense system against bacteria. Here, we report that a 26-residue C-terminal peptide (Lpcin P) can be generated by trypsin proteolysis of PP3 and that structural and functional studies of Lpcin P indicate that the peptide has antibacterial properties. The Lpcin P showed α-helical structure in both anionic and organic solvents, and the amount of α-helical structure was increased in the presence of lipid vesicles. Oriented circular dichroism showed that Lpcin P oriented parallel to the membrane surface. However, the peptide permeabilized calcein-containing vesicles efficiently. Lpcin P displayed antibacterial activity against Streptococcus thermophilus, but not against Staphylococcus aureus and Escherichia coli. The PP3 full-length protein did not display the same properties, which could indicate that PP3 functions as a precursor protein that upon proteolysis, releases a bioactive antibacterial peptide.