High Amounts Of Lactic Acid Research Articles

Development and Characterization of Sodium Bicarbonate-Based Gel for Cytolytic Vaginosis

Background/Objectives: Cytolytic vaginosis or, classically, Doderlein’s cytolysis is characterized by significant growth of species of the Lactobacillus genus, which leads to high amounts of lactic acid in the vaginal environment. Lactobacillus crispatus has been proposed as a key pathogen in this clinical condition. The symptomatology of cytolytic vaginosis is commonly confused with that of vulvovaginal candidosis, leading to inadequate and ineffective azole therapies. Nevertheless, historically, the use of sodium bicarbonate intimate baths was an effective way to reduce the symptoms of cytolytic vaginosis. Methods: In this study, four HPMC gel prototypes were developed, containing sodium bicarbonate concentrations ranging from 4% to 7% (w/w). These gels were evaluated for their physicochemical properties, antimicrobial activity, interference with lactobacilli adhering to cells, and cellular and tissue biocompatibility. Results: The gels presented pH values of around 9.0, and osmolality between 706 mOsm/kg (F4) and 1065 mOsm/kg (F7). The viscosity upon heating to physiologic temperature and dilution with simulated vaginal fluid was highly affected by the concentration of sodium bicarbonate. Gels with higher sodium bicarbonate concentrations (F6 and F7) were not shown to be stable in these conditions. All formulations exhibited effective antimicrobial activity against seven L. crispatus strains, with MIC values ranging from 6.25% to 25% (v/v) in terms of dilution. Additionally, the 4% (w/w) gel significantly interfered with the adhesion of L. crispatus to epithelial cells in competition and exclusion assays, reducing adhesion by more than 90% in relation to the control. Cytotoxicity tests on the Hec-1A, HeLa, and VK2/E6E7 cell lines indicated that the F4 and F5 gels demonstrated lower cytotoxicity levels compared to those with higher concentrations. Furthermore, ex vivo assays using porcine vaginal tissue confirmed that the 4% gel was non-toxic at a 25% (v/v) dilution. Conclusions: Based on these results, the 4% (w/w) sodium bicarbonate gel (F4) emerges as a promising therapeutic option for cytolytic vaginosis, offering effective bacterial interference, favourable physicochemical properties, and biocompatibility suitable for vaginal application.

Vinegar postbiotic solutions obtained from five red fruits processed using traditional methods exhibit different biochemical properties and antimicrobial and antioxidant effects

AbstractPomegranate, hawthorn, gilaburu, blackberry, and rosehip vinegar postbiotic solutions (VPS) were produced by traditional methods. The bioactive components of VPS, antioxidant capacity, antimicrobial activities, minimum inhibition concentration (MIC), and minimum bactericidal concentration (MBC) assays were determined. While rosehip VPS has the highest amount of lactic acid, phenolic and flavonoids, gilaburu VPS has the highest butyric acid. The highest antimicrobial activities were observed for hawthorn VPS on C. albicans and S. aureus, for gilaburu VPS on S. poona and S. aureus, for blackberry VPS on C. albicans mold and S. agalactiae, for pomegranate VPS on E. coli and S. agalactiae and for rosehip VPS on C. albicans and S. agalactiae. Moreover, the mortality values were reported as MBCs: hawthorn for S. aureus (94.6% at 0.03 mg mL−1) and S. paratyphii A (94.1% at 0.03 mg mL−1), gilaburu for S. aureus (93.4% at 0.06 mg mL−1) and P. aeruginosa (93.2% at 0.13 mg mL−1), rosehip for S. agalactiace and E. coli (93.7–91.7% at 0.06 mg mL−1), pomegranate for methicillin‐resistant S. aureus (96.0% at 0.5 mg mL−1), and blackberry for S. aureus (91.3% at 0.25 mg mL−1) and P. aeruginosa (92.1% at 0.13 mg mL−1), in addition to an equal mixture of the five VPSs for S. aureus and P. aeruginosa (85.6% at 0.06 mg mL−1). The MICs for VPS were generally found in a 0.5 mg mL−1dilution of each vinegar. Remarkably, common and local fruits can be rich sources of bioactive components without the need for imported products or expensive processing methods or equipment. This study demonstrated that rosehip VPS has the greatest potential as both a nutrient and a natural disinfectant.

Poly(lactic acid) Degradation by Recombinant Cutinases from Aspergillus nidulans.

Poly(lactic-acid) (PLA) is a biodegradable polymer widely used as a packaging material. Its monomer, lactic acid, and its derivatives have been used in the food, cosmetic, and chemical industries. The accumulation of PLA residues leads to the development of green degrading methodologies, such as enzymatic degradation. This work evaluates the potential use of three cutinolytic enzymes codified in the Aspergillus nidulans genome to achieve this goal. The results are compared with those obtained with proteinase K from Tritirachium album, which has been reported as a PLA-hydrolyzing enzyme. The results show that all three cutinases act on the polymer, but ANCUT 1 releases the highest amount of lactic acid (25.86 mM). Different reaction conditions assayed later led to double the released lactic acid. A decrease in weight (45.96%) was also observed. The enzyme showed activity both on poly L lactic acid and on poly D lactic acid. Therefore, this cutinase offers the potential to rapidly degrade these package residues, and preliminary data show that this is feasible.

Investigating the efficacy of an exopolysaccharide (EPS)-producing strain Lactiplantibacillus plantarum L75 on oat silage fermentation at different temperatures.

This study investigates the effectiveness of an exopolysaccharide (EPS)-producing strain (Lactiplantibacillus plantarum L75) alone or in combination with Saccharomyces cerevisiae on the fermentation characteristics, antioxidant capacities and microbial community successions of oat silage stored at various temperatures. A rapid decrease in pH and lactic acid accumulation was observed in silages treated with L. plantarum and S. cerevisiae (LS) as early as 3 days of ensiling (p < 0.05). Over the ensiling period of 7-60 days, L. plantarum (L)-inoculated groups showed the lowest pH, lowest ammonia nitrogen and the highest amount of lactic acid regardless of the storage temperatures. When the oat silage was stored at 15°C, LS-inoculated group exhibited a higher superoxide dismutase (SOD) activity than control and L-inoculated group. Furthermore, the proportion of Lactiplantibacillus in the combined inoculation group increased by 65.42% compared to the L-inoculated group (33.26%). Fungal community data revealed abundant Penicillium carneum in the control and L-inoculated groups stored at 15°C. Conclusively, these results showed that combined inoculation of L. plantarum L75 and S. cerevisiae improved the fermentation quality of oat silage at 15°C, thus proposing a technique for enhancing the fermentation quality of silage in regions with low temperatures during harvest season.

Poultry Gastrointestinal-derived Lactic Acid Bacteria (pGIT-d-LAB) Inhibit Multiple Antibiotics Resistance Bacterial and Fungal Pathogens.

To develop a probiotic formulation for poultry feed, a few poultry gastrointestinal derived lactic acid bacteria (pGIT-d-LAB) were isolated from chicken intestinal specimens and in vitro experiment was performed to evaluate their efficacy as potential probiotic candidate. A total of 6 strains of LAB: Lactobacillus brevis (L. brevis), Lactobacillus acidophilus (L. acidophilus), Lactobacillus casei (L. casei), Pediococci spp, Lactobacillus fermentum (L. fermentum) and Lactobacillus plantarum (L. plantarum) were isolated and cultured for collection of Cell Free Supernatant (CFS). CFS collected was tested against pathogenic bacterial isolated from chicken feces as well as prevalent fungal pathogens, utilizing agar-well diffusion techniques. A preliminary investigation into the susceptibility of the pathogens to diverse antibiotics and antifungal drugs was conducted. Bacterial pathogens exhibiting resistance to a minimum of three classes of antibiotics were subsequently identified for pGIT-d-LAB CFS screening. The observed results revealed that the CFS derived from the isolates exhibited varying degrees of growth inhibition against different pathogens. Among the tested pGIT-d-LAB isolates, L. acidophilus demonstrated the most prominent zone of inhibition, measuring 18 mm against Klebsiella pneumoniae ZTAC 1233. Notably, Citrobacter diversus ZTAC 1255 showed resistance to all tested pGIT-d-LAB. Quantification of the metabolites produced was performed, and peak production levels was determined. L. acidophilus produced the highest amount of lactic acid (1.789g/l), Pediococci spp. produced the highest amount of diacetyl and H202 (1.918g/l) (0.0025g/l) at 48 hr peak values respectively. The test isolates are potential probiotic candidates for controlling pathogens in poultry.

Evaluation of the Usage of Wafer Waste as an Easily Soluble Carbohydrate Source in Alfalfa Silage

This study examined the addition of wafer waste as a readily soluble carbohydrate source to alfalfa silage for its impact on silage quality, fermentation characteristics, in vitro organic matter digestion, and in vitro CH4 values. Fresh alfalfa was ensiled with 0% wafer waste (Control), 1% wafer waste, 2% wafer waste, 4% wafer waste, and 6% wafer waste for 60 days. The differences between the groups in dry matter (DM), crude protein (CP), crude ash (CA), neutral detergent fiber (NDF), acid detergent fiber (ADF), metabolizable energy (ME), in vitro organic matter digestion (IVOMD), and in vitro CH4 values of silages were found to be statistically significant. In comparison to the control group, increases in IVOMD and ME values were seen in all additive-containing groups. Depending on the quantity of wafer waste, the pH, ammonia nitrogen (NH3-N/TN), and carbon dioxide (CO2) values of the silages declined. In the study, the highest amount of lactic acid occurred in the group with 6% wafer waste added. Propionic acid (PA) was detected only in the control group. Butyric acid (BA) values tended to decrease depending on the addition of wafer waste and were not found in the groups to which 4% and 6% wafer waste addition. Yeast and mold values of the silages decreased in parallel with the increase in the wafer waste rate. As a result, it was determined that adding wafer waste as an easily soluble carbohydrate source positively affected alfalfa silage quality and fermentation characteristics.

Antimicrobial Effects of Lactic Acid Bacteria on Food-Borne Pathogens Isolated from Some Fruits Sold in Ibadan, Nigeria

This study was conducted to determine the antimicrobial effect of Lactic acid bacteria on food-borne pathogens isolated from some fruits sold in Ibadan, Nigeria. Lactobacillus species isolated from healthy fruits include L. casei, L. brevis, L. desidosus, L. jenseni, Lactiplantibacillus plantarum and Fructilactobacillus spp. while Aeromonas hydrophylia, Enterobacter aerogene, Escherichia coli, Salmonella typhii, Shigella dysentriae, Pseudomonas fluorescens, Bacillus megaterium, Candida valida, Saccharomyces cerevisiae, Rhizopus stolonifer were isolated from spoilt fruits using pour plate technique and biochemical test. Gram-negative isolates were 100% resistant to Cefuroxime, Amoxycillin/Clauvulanate, and Ampicillin while 93.75% of the isolates were highly sensitive to Ofloxacin. Gram-positive isolates were 100% resistant to Cloxicillin and highly sensitive to Ofloxacin and Gentamycin using an antibiotic disc. Lactiplantibacillus plantarum had the highest amount of Lactic acid (5.6 g/l) while L. casei had the lowest yield (3.6 g/l) at 48 hours. L. casei had the highest amount of hydrogen peroxide (0.00036 g/l) while Lactiplantibacillus plantarum. and Fructilactobacillus spp. had the lowest yield (0.00021 g/l) at 48 hours. The highest amount of diacetyl (3.01 g/l) was produced by L. jenseni while the lowest amount was observed in L. brevis (0.43 g/l) at 48 hours. The maximum inhibitory activity was observed in L. brevis against B. megaterum with a diameter of 18mm zone of inhibition while the minimum activity by L. desidosus, L. jenseni, Fructilactobacillus spp. was observed against B. subtilis and Lactiplantibacillus plantarum against K. pneumoniae with diameter 8 mm zone of inhibition. The antimicrobial compounds produced by the Lactic Acid Bacterial had antimicrobial effects on food-borne pathogens.

G-C3N4-based photoresponsive magnetic nanocatalyst drives type-I photodynamic therapy under visible light irradiation, boosting chemo/chemodynamic synergistic therapy of colon cancer

BackgroundFenton reaction-based chemodynamic therapy (CDT) is regarded as a highly tumor-specific treatment modality due to its intrinsic tumor microenvironment (TME)-specific targeting properties, such as high amounts of lactic acid and H2O2. To improve the therapeutic efficacy of CDT, in this study, a self-tracking and external stimuli-responsive Fenton nanoreactor was accompanied by type I photodynamic therapy.ResultsA cisplatin-containing H2O2 self-supplying heterogeneous Fenton nanocatalyst (CaO2.CDDP@Fe3O4) was constructed, and it was accompanied by graphitic carbon nitride (g-C3N4) nanosheets as a photosensitizer. The hybrid nanocomposite was decorated with ascorbic acid, which improved the tumor-targeting capabilities of the final construct (CCFCA). Besides the generation of hydroxyl radicals (·OH) by metal-based Fenton nanocatalyst (CaO2.CDDP@Fe3O4), g-C3N4-driven nonmetal-based Fenton reaction translated external energy into extremely lethal free radicals within the tumor cells through oxygen-independent type-I PDT. According to 2D and 3D cell culture experiments, CCFCA demonstrated cancer cell selectivity and a high cellular uptake efficiency under a static magnetic field (SMF) and visible light irradiation. Further investigations showed that CCFCA suppressed the antioxidant system and altered the mitochondrial membrane potential and consequently caspase activity, causing apoptosis in cancer cells. The enhanced tumor-inhibitory capability of the nanocomposites was shown by the increased anti-tumor activity of CCFCA in treated mice under SMF and light irradiation as compared to those treated with the free drug. Moreover, no deleterious effects on normal tissues and blood cells were observed in CCFCA-treated mice.ConclusionBased on the results obtained, dual Fenton reactions were provided in a simple platform (CCFCA) where the cooperative combination of multiple approaches (chemotherapy, magnetic therapy, and PDT) enhanced CDT efficiency against colon cancer.

Fouling of ion-exchange membranes during electrodialytic acid whey processing analysed by 2D fluorescence and FTIR spectroscopy

Acid whey (AW), a by-product from the production of acidified dairy products, contains high amounts of lactic acid and minerals that can be recovered by electrodialysis (ED). To better understand the process and improve its efficiency, the objective of this study was to investigate fouling of ion-exchange membranes (IEMs) during ED of AW and concentrated AW by reverse osmosis (ROAW), underlimiting (ULCD), limiting (LCD) and overlimiting current density operating conditions (OLCD). The structure, hydrophobicity, and chemical composition of membranes showed differences regarding fouling on anion- (AEM) and cation- (CEM) exchange membranes facing the diluate and the concentrate, both for AW and ROAW. Furthermore, operating at OLCD tends to reduce fouling compared to ULCD, due to the expected generation of electroconvective vortices. 2D fluorescence spectroscopy and Fourier-transform infrared spectroscopy (FTIR) provided complementary and more detailed information regarding the fouling and efficiency of the cleaning procedure. The 2D fluorescence spectra showed that the AEM surfaces in contact with the diluate change more than those in contact with the concentrate. The FTIR analyses showed the presence of lactose and lactic acid on the AEM surfaces in contact with the concentrate, which could not be detected by fluorescence.

Extraction and Characterization of Cocoa Bean Shell Cell Wall Polysaccharides.

Cocoa bean shells (CBS), a by-product of the cocoa industry, from two cacao varieties and obtained after selected processing conditions (fermentation, drying, roasting) were characterized in terms of their chemical composition, where they were found to be a great source of carbohydrates, specifically dietary fiber, protein, ash, and polyphenols, namely quercetin, epicatechin, and catechin. Cell wall polysaccharides were isolated by alkaline extraction (0.5 M or 4 M KOH) and were found to be enriched primarily in pectic polysaccharides (80.6-86%) namely rhamnogalacturonan and arabinogalactan as well as hemi- cellulosic polysaccharides (13.9-19.4%). Overall, 0.5 M KOH polysaccharides were favored having provided a diverse profile of neutral sugars and uronic acids. When tested for the promotion of the growth of selected probiotic strains, CBS cell wall polysaccharides performed similarly or more than inulin and rhamnogalacturonan based on the prebiotic activity scores. The short-chain fatty acid profiles were characterized by high amounts of lactic acid, followed by acetic and propionic acid.

Evaluation of Antibacterial Activity of Lactic Acid Bacteria Isolated from Kunun Zaki against Selected Bread Rope Spoilage Bacteria

In line with increasing demand by consumers for safe and minimally processed food products, biopreservation has been advocated over the traditional use of chemical additives in combating food spoilage. This study evaluated the antibacterial activity of four lactic acid bacteria (LAB) (Lactobacillus fermentum, Lactococcus lactis, Lactobacillus brevis and Lactobacillus plantarum) isolated from kunun-zaki against the bread rope spoilage bacteria, Bacillus subtilis and Bacillus cereus. Antibacterial activity was determined using the dual agar overlay method with subsequent measurement of zones of inhibition. Titrimetric methods were used to determine the abilities of the isolated LAB to produce antimicrobials including lactic acid, hydrogen peroxide and diacetyl. Lactobacillus fermentum brought about the highest inhibition zone (20 mm) against Bacillus cereus. The smallest zone of inhibition (6 mm) was recorded for L. plantarum against B. cereus. Whereas L. plantarum produced the highest amount of lactic acid (0.540 g/L), L. brevis produced the lowest lactic acid amount of 0.348 g/L. L. fermentum produced the highest amount of hydrogen peroxide (0.020 g/L) whereas L.brevis recorded the lowest hydrogen peroxide production of 0.010 g/L. L. lactis and L. fermentum had the highest and lowest values of 0.649 g/L and 0.219 g/L respectively for diacetyl production. Differences in the antibacterial activities and antimicrobials production by the LAB were statistically significant (P &lt; .05). The findings show that the LAB isolates possessed antibacterial activity against the selected spoilage bacteria and as such could be exploited as potential biocontrol agents against the selected bread rope spoilage bacteria.

An animal derivative-free medium enhances Lactobacillus johnsonii LJO02 supernatant selective efficacy against the methicillin (oxacillin)-resistant Staphylococcus aureus virulence through key-metabolites

The spread of multidrug-resistant bacteria, such as the skin commensal Staphylococcus aureus, is a worldwide health challenge; new methods to counteract opportunistic pathogen growth and virulence are urgent. We compared the activity of Lacticaseibacillus rhamnosus LR06 (DSM 21981) and Lactobacillus johnsonii LJO02 (DSM 33828) cell-free supernatants (CFSs) produced in the conventional animal derivative-based MRS medium and an innovative animal derivative-free broth (TIL) versus the MDR S. aureus (ATCC 43300). CFS influence was assessed towards the viability, metabolic activity, and ability to form biofilm of the MDR strain through optical density, alamarBlue assay, and crystal violet staining; their content in short-chain fatty acids, lactic acid, and proteins was analysed via high-resolution mass spectrometry and gas chromatography. All CFSs reduce viable and metabolically active S. aureus, being TIL more efficient compared to MRS in stimulating lactic acid bacteria metabolism and decreasing S. aureus biofilm formation. Particularly, the CFS from LJO02 grown in TIL has the best efficacy, revealing a high amount of lactic acid and 59 peculiar proteins; its effectiveness is partially maintained upon trypsin and proteinase K treatments, but not by pepsin and pH basification. Therefore, antagonistic CFSs may represent a strategic prevention approach, with bacteriotherapeutic and bio-repair potential.

Biochemical content, minerals, and antioxidant activity of fruit jiaosu obtained by natural fermentation

This study was conducted to determine the pH, protein concentration, mineral, phenolic, flavonoid, and organic acid contents, as well as the antioxidant activity of three batches of fruit jiaosu (F1B3, F1B4, and F1B5). The jiaosu was prepared by mixing ten types of fresh fruits, raw honey, and water (3:1:10, w/w/w), and fermented at room temperature for six months. All fruit jiaosu had low pH (2.96–3.69), and the protein concentration was ranged from 8.45 to 16.2 µg/mL. Potassium (605.0–657.2 mg/L) was found to be the most abundant mineral in all the samples, followed by magnesium, calcium, and sodium. The total phenolic and flavonoid contents were 183.1–210.5 µg gallic acid equivalent/mL and 45.2–53.8 µg quercetin equivalent/mL, respectively. Acetic acid was the major organic acid in the F1B4 and F1B5 samples (6.58 g/L and 20.7 g/L, respectively) while the F1B3 sample contained the highest amount of lactic acid (12.1 g/L). Ascorbic and citric acids were present in small amounts in all samples. All the samples showed stronger scavenging activity against 2,2-diphenyl-1-picrylhydrazyl radicals (half-maximum inhibitory concentration, IC50: 13.6–16.8% v/v) than against hydrogen peroxide (IC50: 47.2–50.6% v/ v). The ferric reducing antioxidant power and oxygen radical absorbance capacity values for the samples were 14.9–20.9 µg ascorbic acid equivalent/mL and 23.9–25.4 mg Trolox equivalent/mL, respectively. The results indicated that the fruit jiaosu is a complex acidic solution containing proteins, minerals, phenolic compounds, and organic acids with antioxidant activities. Natural fermentation may cause variations in the organic acid content of the fruit jiaosu.

Application of mixed starter culture for table olive production

The fermentation of olives is usually carried out spontaneously by natural microbiota. Spontaneous fermentation has some disadvantages, such as the formation of defects in the end product due to the activities of undesirable microorganisms. The use of starter cultures could be a promising option to provide a more controlled fermentation environment and to reduce the risk of spoilage. Mixed starter culture use (generally selected Lactobacillus strains with or without yeasts) could reduce pH in a shorter time, producing a higher amount of lactic acid and enhancing microbial safety compared to fermentation with starter cultures containing single species or natural fermentation. Their use could also enhance the organoleptical properties of table olives. Particularly the use of yeast (such as strains of W. anomolus, S. cerevisiae) in the fermentation of olives, in combination or sequentially with lactic acid bacteria could result in an increase in volatile compounds and a more aromatic final product.

Valorisation of brewers’ spent grain in different particle size in yogurt production

The potential of brewers’ spent grain (BSG) as a functional food ingredient has been investigated for having high nutritional value. A high amount of dietary fiber of BSG shows a high ability to bind water; thus, it tends to solidify food mixture. This characteristic has a beneficial effect in the utilization of BSG as a filler and texturizer in yogurt. The study aims to evaluate the impact of the BSG addition in yogurt production and its quality. BSG was prepared in three different particle sizes, and an amount of 10% was added for yogurt fermentation. The impact of BSG addition was evaluated after 24 h of storage. The result shows that different particle sizes of BSG had no significant impact on pH and syneresis, while it significantly affected the amount of lactic acid and countable S. thermophilus. However, BSG increased the fermentation rate of yogurt, and had a positive impact on water holding capacity. A lower particle size had a higher amount of lactic acid and a lower S. thermophilus. The lower particle size lowered the lightness of the yogurt. Rheological analysis showed that a higher particle size of BSG increased the shear stress and viscosity of yogurt.

Efficient two-step lactic acid production from cassava biomass using thermostable enzyme cocktail and lactic acid bacteria: insights from hydrolysis optimization and proteomics analysis.

Lactic acid is an intermediate-volume specialty chemical, used in the production of biodegradable polymers and other chemicals. Although lactic acid production process is well established, however, the cost of production is very high. Therefore, in this study; starchy biomass (cassava) was hydrolyzed with in-house enzyme cocktail prepared from Aspergillus foetidus MTCC508 and Bacillus subtilis RA10. Process optimization using Taguchi experimental design helped to optimize the most effective ratio of fungal and bacterial amylase for effective saccharification of cassava. A higher sugar yield of 379.63mg/gds was obtained under optimized conditions, using 30U/gds of bacterial enzyme and 90U/gds of the fungal enzyme at pH 4 within 48h of saccharification. Among 11 lactic acid bacteria isolated, Lactobacillus fermentum S1A and Lactobacillus farraginis SS3A produced the highest amount of lactic acid 0.81g/g and 0.77g/g, respectively, from the cassava hydrolysate. The study proved the potential renewable source of cassava biomass as a source for fermentable sugars that can be fermented to lactic acid with high yield. In future, this cost-effective and environmental-friendly bioprocess can be upscaled for industrial lactic acid production.

Role of Streptococci as etiological agents of dental caries

Dental plaques are notorious and lead to dental caries responsible for dental decay. Streptococci are the leading microorganisms associated with dental plaques. These are Gram-positive, normal microbial flora, non-motile, non-spore forming, and facultative anaerobes. These include Alpha, Beta, and Gamma hemolytic species. Streptococcus sp. produces a high amount of lactic acid through the fermentation of sugars, causes lowering of the pH leading to the plaque formation around teeth, and serves as a biofilm. Microbial biofilm provides certain attachment sites for growth and colonization of other bacteria, and also causes resistance to the antimicrobial agents. These Streptococci can be transmitted to the infants through parents or caretakers' kiss. This mode of transmission is the key role for the contribution of S. mutans in dental caries. In Pakistan, a national survey was conducted in 1992 on tooth decay, which showed that two teeth per person were decayed, missing, or filled, thus becomes an alarming situation. Minimal knowledge related to tooth decay is observed in the clinical settings; however, no similar studies have been carried out in Pakistan.

The efficacy of cell-free supernatants from Lactobacillus plantarum Cs and Lactobacillus acidophilus ATCC 314 for the preservation of home-processed tomato-paste

The unsafety concern associated with the chemical preservatives and the understanding of the preservative potential of lactic acid bacteria on varied food substances led to the present study which was aimed at the evaluation of the bio-preservative potential of L. plantarum Cs and L. acidophilus ATCC 314 on home-processed tomato paste. The test organisms were activated in glucose supplemented deMan Rogosa Sharpe broth under stationary condition at 37 °C for 36 h to produce cell-free supernatants (CFSs) which were concentrated to 50% with 5 M sucrose solution and precipitated with 4 °C acetone respectively. The treated CFSs were first exposed to chemical analysis prior to their antimicrobial sensitivity to the indicator organisms (Staphylococcus aureus, Escherichia coli, Aspergillus niger and Aspergillus flavus). The minimum inhibitory concentration (MIC) of the most active CFS was selected for shelf-life study on home-processed tomato paste at room temperature for 45days. Among the detectable amount of CFS biomolecules, a significant (P>0.05) high amount of lactic acid (6.491±0.017 mg/ml) was recovered from concentrated CFS from L. acidophilus ATCC 314 while precipitated CFS from L. plantarum Cs had the highest significant protein molecules (0.863±0.013 mg/ml). However, the concentrated CFS (cCFS) from both test organisms at 100% demonstrated the strongest antimicrobial activity to all the indicator organisms among the other two CFSs. Their inhibitory effect was greater on Staphylococcus aureus (11.9±0.10–12.85 ± 0.08 mm) than E. coli (7.57 ± 0.06–8.15±0.05 mm) and Aspergillus niger (5.94 ± 0.08–6.98 ± 0.06) than Aspergillus flavus (5.05± 0.04–5.60 ± 0.05). The L. plantarum Cs and L. acidophilus ATCC 314 cCFSs- treated tomato pastes significantly (P>0.05) extended the pastes shelf-life to 25 and 30 days respectively. However, the 5 days’ shelf-life extension of the tomato paste by L. acidophilus ATCC 314 cCFS as compared to that from L. plantarum Cs was insignificant (P>0.05). The increase in shelf-life of the home-processed tomato paste suggests the possible use of L. plantarum Cs and L. acidophilus ATCC 314 CFS as bio-preservatives in tomato processing.

Enterocin Structural Gene Screening in Enterococci from Pannon White Breed Rabbits.

This study was focused on screening the most frequently occurring enterocin (Ents) genes in faecal enterococci from the Pannon White breed of rabbits, in which this parameter never has been tested. Enterococci tested were Ent genes absent, except Enterococcus faecium EF9a, which possessed genes for four Ents. Strains produced a high amount of lactic acid (1.25 ± 0.055mmol/L, on average) and sufficiently tolerate bile. Inhibition activity of crude bacteriocin substance-partially purified (Ent, CE EF9a)-was tested against altogether 53 indicator strains. The growth of 38 strains of different staphylococcal species was not inhibited. However, the growth of fifteen other Gram-positive indicators was inhibited with inhibition activity ranged from 100 to 12,800AU/mL. Listeria monocytogenes LM 7562 was the most susceptible to CE EF9a treatment (12,800AU/mL). Molecular mass of CE EF9a ranged between 3000 and 10,000Da. After heat treatment at different temperatures and time, CE EF9a was active with the inhibition activity 12,800AU/mL. After storage of CE EF9a at different conditions, it was active even after 2-month storage at room temperature (200AU/mL against LM 7562 strain). Inhibition activity of CE EF9a after 2-month storage at 4°C was 1600AU/mL and the most stable was CE EF9a at - 20°C; the activity 12,800AU/mL was kept still after 2months. It indicates a small, thermostable substance; however, in further detail, purification analysis is necessary.

Probiotic Characteristics and Antifungal Activity of Lactobacillus plantarum and Its Impact on Fermentation of Italian Ryegrass at Low Moisture

The study aimed to investigate probiotic characteristics, and low moisture silage fermentation capability of selected lactic acid bacteria (LAB) isolated from Alfalfa (Medicago sativa L). Morphological and physiological properties, carbohydrates fermentation, enzymes, and organic acids production, anti-fungal activity, antibiotic sensitivity patterns, and probiotic characteristics (acidic and bile salt tolerances, hydrophobicity and aggregations natures) of LAB were examined. 16SrRNA sequencing was carried out to identify isolated strains. The identified strains Lactobacillus plantarum (KCC-37) and Lactobacillus plantarum (KCC-38) showed intense antifungal activity, survival tolerant in acidic and bile salt environments, cell surface and auto aggregations ability, enzymes and organic acids productions. At ensiled condition, KCC-37 and KCC-38 enhanced acidification of Italian ryegrass silages by producing a higher amount of lactic acid, a key acid for indicating silage quality with less extent to acetic acid and succinic acid at low moisture level than non-inoculated silages. Notably, the addition of mixed strains of KCC-37 and KCC-38 more potentially enhanced acidification of silage and organic acid productions than the single-culture inoculation. The overall data suggested that these strains could be used as an additive for improving the quality of the fermentation process in low moisture silage with significant probiotic characteristics.