Lactic Acid Bacteria Cultures Research Articles

Evaluation of the bioprotectivity of Lactobacillus binary/ternary cultures in yogurt.

The attempts toward addition of biocontrol agents in dairy products have gained popularity. Here, we worked on analysing the antifungal activity of binary and ternary combinations of three Lactic Acid Bacteria (LAB) against five spoilage yeasts in yogurt. The yogurt samples were characterized in terms of pH, acidity, WHC, textural parameters, viscosity, survivability and antifungal activity of LAB and sensorial properties during cold storage. The results showed that the inoculation of LAB in yogurt gave rise in significant reduction of pH throughout cold storage while titrable acidity and WHC decreased (p < .05). Inoculation of LAB resulted in significant increase in hardness and adhesiveness while springiness remained constant. On the other hand, apparent viscosity of all samples experienced a profound increase up to the 10th day of storage followed by a reduction trend for the rest of storage period. Analysis of inhibitory activity of LAB showed an efficient barrier against all five yeasts, in which the most activity was recorded for Lactobacillus reuteri followed by Lactobacillus acidophilus. On the other hand, the most resistance yeast was Kluyveromyces marxianus followed by Rhodotorula mucilaginosa. Sensorial analysis revealed that addition of LAB in yogurt brought about a profound improvement in textural quality of samples. Inoculation of LAB cultures in yogurt at 5% (v/v) not only could improve the physicochemical and sensorial properties of yogurt, but also could introduce a strategy toward substituting of chemical preservatives with biocontrol agents.

Technological variables influencing the growth and stability of a silage inoculant based on spray-dried lactic acid bacteria.

To investigate the influence of different culture media and fermentation conditions on growth performance and viability of three lactic acid bacteria (LAB) strains with potential as silage inoculants, and to optimize spray-drying in order to enhance survival to dehydration and storage stability. In house-formulated MRS was a suitable low-cost culture medium for Lactobacillus plantarum Hv75, Pediococcus acidilactici 3903 and L. buchneri B463. Uncontrolled pH biomass production conferred enhanced stability during storage at 4°C after spray-drying. The use of whey protein concentrate 35 (WPC)-maltodextrin (M) as matrix, inlet temperature of 145-150°C and air flow rate of 601lh-1 was adequate for the production of dehydrated LAB. According to the desirability function, at this optimized condition, moisture content, yield and solubility were predicted to be 3·96, 73·68 and 90·36% respectively. Those conditions also showed a decrease of 0·855 log CFU per gram after drying, no loss in viability at 4°C for 6months and 1 log CFU per gram reduction at 25°C. Stable and economically feasible dehydrated LAB cultures were obtained using alternative culture media, fermentation under uncontrolled pH and optimizing spray-drying process conditions through the desirability function method. Our results can be utilized for efficient production and commercialization of several dry LAB.

Isolation, identification and antimicrobial activities of Lactic Acid Bacteria from fruits of wild plants in Tambrauw Forest, West Papua, Indonesia

Abstract. Dinoto A, Rosyidah A, Susilo ARPS, Julistiono H. 2020. Isolation, identification and antimicrobial activities of Lactic Acid Bacteria from fruits of wild plants in Tambrauw Forest, West Papua, Indonesia. Biodiversitas 21: 3391-3397. Presence of culturable lactic acid bacteria (LAB) in fruits of wild plants and their antimicrobial activities has not been widely reported. The purposes of this study were to isolate LAB from the fruits of wild plants found in the Tambrauw forest area, West Papua Indonesia, and to evaluate their antimicrobial activities. Isolation of LAB from fruit was conducted using MRS medium supplemented with 1% CaCO3. Isolates of LAB were identified based on 16S rRNA gene using BLAST analysis. Antimicrobial assays were carried out by determining the minimum inhibitory concentration (MIC) based on thiazolyl blue tetrazolium blue (MTT) using indicator microorganisms Escherichia coli, Staphylococcus aureus, and Mycobacterium smegmatis. The results showed that total of fourteen isolates of LAB with different characteristics was successfully isolated from 8 of 14 collected wild plants. Based on 16S rRNA sequences, isolates had closest relationships with Lactococcus lactis, Lactococcus garvieae, Weissella confusa, Weissella oryzae, and Enterococcus faecalis with the similarity of 99%. All 16S rRNA nucleotides of these strains have been deposited in the GenBank. Assays for antimicrobial activities were demonstrated by the highest inhibition of supernatant of Lac. lactis HM 1.1 from fruit plant Donax canniformis and W. confusa H14.2 from fruit plant Capparis sp. against E. coli, S. aureus, and M. smegmatis even though the MIC values of those strains were lower than that of bacterial strain from the commercial probiotic product. This study showed that wild fruit from Tambrauw forest harbor beneficial lactic acid bacteria that could be important for health of animals and humans as well. In addition, this study provided basic information on indigenous LAB for promoting further development of medicinal antibacterial compounds.

Probiotic and technological features of Enterococcus and Weissella isolates from camel milk characterised by an Argane feeding regimen.

The objectives of this study were to isolate lactic acid bacteria (LAB) from a raw Moroccan camel milk collected after the incorporation of a specific Argane by-products diet, and to investigate their technological properties as well as their probiotic features. The molecular identification of the isolates indicated that they belong to Weissella confusa, Weissella cibaria or Enterococcus durans species. Our results revealed that the tested isolates have a fast acidifying ability (values ranging between 0.045 ± 0.01 to 0.93 ± 0.01 after only 4h incubation), important proteolysis, autolysis, lipolytic activities and an important diacetyl and exopolysaccharides production. All these isolates demonstrated a high tolerance to gastrointestinal conditions, namely to gastric simulated juice (survival rate ranged between 75.05 ± 7.88 and 85.55 ± 1.77%) and to bile salts (survival rate between 42.79 ± 1.11 and 82.75 ± 1.01%). The autoaggregation, hydrophobicity and antioxidant activity mean values of the isolates were 13.26-41.16%, 13.23-54.47% and 47.57-63.31%, respectively. Importantly, LAB cultures exhibited antibacterial activity against Gram-negative and Gram-positive pathogenic bacteria and none of the tested isolates presented antibiotic resistance, haemolytic or DNase activities. This study revealed interesting properties for LAB isolated and supported their utilization as autochthone starters for camel milk fermentation that represent a challenge process. These results presented as well the probiotic potential for a possible human consumption.

Isolation and screening of lactic acid bacteria associated with the gastrointestinal tracts of abalone at various life stages for probiotic candidates

Members of lactic acid bacteria (LAB) have been well-known for probiotic agents owing to their ability to produce diverse beneficial compounds for cultured species, as well as for having a status of generally recognized as safe microorganisms. Considering these facts, the current study investigated the presence of cultivable LAB associated with the gastrointestinal tracts (GIT) of hybrid abalone (Haliotis laevigata x H. rubra Brown 1992) at various life stages (larvae, juvenile, and adult), and screened them for their probiotic properties. GITs of 90 hybrid abalone (30 larvae, 30 juveniles, and 30 adult stages) were dissected out aseptically and then inoculated into de Man Rogosa Sharp (MRS) broth and agar. The result revealed that no LAB was isolated from the GITs of abalone at the larval stage. LAB were firstly recorded at the juvenile stage (44 isolates) and the adult stage (49 isolates). Based on partial sequences of the 16S rRNA gene, the 44 LAB in the juvenile stage were identified as five genera and belonged to 10 ribotypes. While the 49 LAB isolates from the adult stage were identified as three genera and belonged to eight ribotypes. Of the 93 LAB, five strains which were Enterococcus faecium MA002, Enterococcus lactis MA056, Leuconostoc mesenteroides MA064, Enterococcus lactis MA068, and Enterococcus lactis MA084, exhibited antagonistic activities against bacterial pathogens (Vibrio alginolyticus and Listeria monocytogenes). The five LAB strains did not show any hemolytic activity, possibly indicating that they were non-pathogen. These results confirmed that LAB colonized the intestinal tract of abalone at juvenile and adult stages and were capable of producing antimicrobial compounds. Acknowledging the presence of indigenous LAB in GITs of abalone, a prebiotic application can be considered for another strategy to modify the healthy microbiome of abalone.

Addition of selected starter/non-starter lactic acid bacterial inoculums to stabilise PDO Pecorino Siciliano cheese production

The present study was carried out to produce Protected Denomination of Origin (PDO) Pecorino Siciliano cheese with a multi-species lactic acid bacteria (LAB) culture, composed of starter and non-starter strains in order to reduce the microbiological variability of the products derived without LAB inoculums. To this end, cheese samples produced in six factories located in five provinces (Agrigento, Catania, Enna, Palermo and Trapani) of Sicily, and previously characterised for physicochemical, microbiological and sensory aspects, have been investigated in this work for bacterial microbiome, fatty acid (FA) composition as well as volatile organic compound (VOC) profiles. Analysis of the cheese microbiomes indicated that streptococci (30.62–77.18% relative abundance) and lactobacilli (on average 25.90% relative abundance) dominated the bacterial communities of control cheeses, produced without exogenous inoculums, whereas the cheeses produced with the selected multi-strain culture saw the dominance of lactococci (in the range 6.49–14.92% relative abundance), streptococci and lactobacilli. After the addition of the selected mixed culture, Shannon index increased in all cheeses, but only the cheeses produced with the selected LAB mixed culture in the factory 2 showed Gini-Simpson diversity index (0.79) closer to the reference value (0.94) for a perfect even community. FA composition, mainly represented by saturated FA (on average 69.60% and 69.39% in control cheeses and experimental cheeses, respectively), was not affected by adding LAB culture. The presence of polyunsaturated FA ranged between 7.93 and 8.03% of FA. VOC profiles were different only for the content of butanoic acid, registered for the experimental cheeses at higher concentrations (on average 662.54 mg/kg) than control cheeses (barely 11.96 mg/kg). This study validated addition of the ad hoc starter/non-starter culture for PDO Pecorino cheese production.

Effect of immature wheat flour on nutritional and technological quality of sourdough bread

In this study, the effect of immature wheat flour (IWF) on the fermentation activity of lactic acid bacteria (LAB) and on the nutritional quality properties of bread were evaluated. IWF was added in the as the ratio of 10g/100g in sourdough fermentation medium, and the fermentation activity (total LAB, pH, titration acidity (TA), and total reducing sugar (TRS)) of LAB cultures was monitored. Additionally, some physical quality characteristics (specific volume, texture profile and colour value), estimated glycaemic index (eGI), rapidly digestible starch (RDS), slowly digestible starch (SDS), and the total dietary fibre content of sourdough bread were determined. According to the statistical test, it was revealed that the IWF addition stimulated LAB growth and increased their fermentation activity. The pH of the fermentation medium decreased from 6.57 to 3.50, and TA raised from 0.13% to 1.2% in 48 h. The highest TRS content was determined in IWF enriched sourdough samples, and as a result of this, the eGI of sourdough bread increased. Compared to the control sample, the SDS and total dietary fibre content were higher in IWF added sourdough bread, and a positive correlation was noted between these two components. IWF utilisation of sourdough bread formulation increased the hardness value by nearly 50%.

The use of cyclic dipeptide producing LAB with potent anti-aflatoxigenic capability to improve techno-functional properties of clean-label bread

PurposeThe aim of the present study was to evaluate the antifungal activity, anti-aflatoxigenic capability, and technological functionality of the selected lactic acid bacteria (LAB) isolated from wheat sourdough.MethodsThe preselected LAB isolates were screened based on their antifungal activities and acidification capacities. Then, the antifungal compounds were identified using gas chromatography/mass spectrometry in the selected LAB culture filtrate obtained from its preparative thin-layer chromatography. The HPLC-based analysis was also used to investigate the anti-aflatoxigenic potentials of the selected LAB isolate. Finally, controlled sourdough (containing selected LAB isolate as starter culture) was used to produce loaf bread, and properties of the product were evaluated in terms of hardness, phytic acid content, overall acceptability, and surface moldiness.ResultsMolecular approaches led to the identification of Pediococcus pentosaceus as the selected LAB isolate. In vitro and in situ antifungal activities of the selected LAB against Aspergillus niger were verified. Antifungal metabolites of the LAB included fatty acid ester, hydroxylated fatty acid ester, an antimicrobial compound, and cyclic dipeptide. Potent anti-aflatoxigenic capabilities of the LAB isolate and cyclic dipeptide (which was identified in the antifungal fraction of the LAB) were also verified. To our best knowledge, the cyclic dipeptide detected in the present study has never been shown before to possess anti-aflatoxigenic effect. Furthermore, the results revealed that controlled sourdough improved the techno-functional properties of the produced loaf wheat bread.ConclusionAltogether, our findings indicate that the selected P. pentosaceus isolate exhibiting proper characteristics can be used as a bio-preservative and bio-improver in the processing of clean-label breads.

Isolation, characterization and selection of potential probiotic lactic acid bacteria from feces of wild boar, native pig and commercial pig

In livestock production, lactic acid bacteria (LAB) play an important role in improving performance, mitigating diseases due to their ability to maintain the balance of gastrointestinal microbes and resistance to pathogenic bacteria. As resident adapted microorganisms, LAB should be isolated and characterized from the homologous host to improve their efficiency as additives in pig feeding. In present study, cultivable LAB numbers from commercial pig (CP), native pig (NP) and wild boar (WB) samples ranged from 4.64 to 7.39 (log10 CFU/g), and the LAB counts in commercial pig and native pig feces were much higher than wild boar. Ninety-six LAB strains were detected in commercial pig, native pig and wild boar feces, being represented by thirteen different species of Enterococcus, Lactobacillus, Pediococcus and Weissella genera. Tests in vitro were conducted including survival in simulated gastrointestinal tract conditions, antimicrobial activity, organic acid production, hydrophobicity, auto-aggregation, Caco-2 surface adhesion, haemolytic activity and antibiotic resistance. According to the results of acid and bile salt resistant and bacteriostatic test, twelve LAB strains were selected as potential probiotics and their cell surface properties were further evaluated. Based on multivariate principal component analysis, nine probiotic LAB strains (Lactobacillus plantarum NCUA001005 and NCUA001014, Pediococcus pentosaceus NCUA006009, Lactobacillus reuteri NCUA064001 and NCUA064006, Lactobacillus johnsonii NCUA063001, NCUA063006 and NCUA063008, Lactobacillus casei NCUA011001) showed better characteristics and might be selected to explore their potential use as probiotics. These strains were good candidates for further investigation in vivo studies to assess their potential health benefits as feed supplements.

Biocontrol of Listeria on cantaloupes with lactic acid bacteria

Efficacy of lactic acid bacteria (LAB) Lactobacillus plantarum and Pediococcus pentosaceus for reducing Listeria on cantaloupes was investigated. Cantaloupe surfaces inoculated with Listeria innocua and Listeria monocytogenes in preharvest and postharvest studies, respectively, were treated with or without LAB. Listeria populations were enumerated on days 0, 1, 5, and 7. At the preharvest level, treatment with unwashed LAB (cultures grown in De Man, Rogosa, and Sharpe) significantly reduced L. innocua by 2.1 log and 1.5 log CFU/cm2 on cantaloupes harvested on days 5 and 7, respectively. At the postharvest level, both unwashed LAB and washed LAB (cultures resuspended in phosphate buffer saline) significantly reduced L. monocytogenes by >2.0 log CFU/cm2 on cantaloupes after 7 days of storage at 25°C; the unwashed LAB treatment exerted higher anti-Listeria efficacy than the washed LAB. Results suggest that these LAB strains offer potential application for reducing Listeria contamination on cantaloupes at preharvest and postharvest levels. Practical applications Listeriosis associated with the consumption of cantaloupes have resulted in 153 illnesses, 148 hospitalizations, and 33 deaths in the United States between 2009 and 2013, which highlight the need for effective interventions to improve cantaloupe safety. Cantaloupes may be contaminated with Listeria at the farm level or during wash step at the packing facility. Lactic acid bacteria (LAB) including Lactobacillus plantarum and Pediococcus pentosaceus can be potentially utilized as biocontrol agents on the surface of the cantaloupes at the farm level or during postharvest wash to reduce the populations of Listeria on cantaloupes. Further, LAB may minimize cross-contamination of Listeria at the postharvest level.

How we can improve the antimicrobial performances of lactic acid bacteria? A new strategy to control Listeria monocytogenes in Gorgonzola cheese

This study was aimed to evaluate the effectiveness of two lactic acid bacteria (LAB) cultures (Lactococcus lactis FT27 and Carnobacteroim divergens SCA), lactic acid/sodium lactate (LASL - l-lactic acid 61% (w/w) and L-sodium lactate 21% (w/w)) and their combination against four Listeria monocytogenes biotypes isolated from Gorgonzola cheese. In vitro antilisterial activity showed that the sensitivity to antimicrobials was strain-dependent. Antimicrobial challenge testing was performed on Gorgonzola rinds simulating contamination occurring at the beginning (6 days) and at the end (55 days) of the ripening period, to assess the antilisterial activity of LAB strains and LASL during the subsequent 60 days at 4 °C. LASL showed a higher antilisterial activity than LAB, maintaining the pathogen content below the EC limit (<2.0 log10 CFU/g) for 60 days. A strong listericidal effect was observed combining LAB with LASL (2,8 μL/cm2) Lc. lactis in combination with LASL completely inhibited the two L. monocytogenes strains in the first 50 days, while LASL with C. divergens was more effective in the second part of ripening when the pH raised. Data obtained encourage the use of LASL along with antimicrobial LAB rotation schemes during cheese ripening for the prevention and/or control of the L. monocytogenes on cheese surface.

Sensory Improvement of a Pea Protein-Based Product Using Microbial Co-Cultures of Lactic Acid Bacteria and Yeasts.

Consumer demands for plant-based products have increased in recent years. However, their consumption is still limited due to the presence of off-flavor compounds, primarily beany and green notes, which are mainly associated with the presence of aldehydes, ketones, furans, and alcohols. To overcome this problem, fermentation is used as a lever to reduce off-flavors. A starter culture of lactic acid bacteria (LAB) was tested in a 4% pea protein solution with one of the following yeasts: Kluyveromyces lactis, Kluyveromyces marxianus, or Torulaspora delbrueckii. The fermented samples were evaluated by a sensory panel. Non-fermented and fermented matrices were analyzed by gas chromatography coupled with mass spectrometry to identify and quantify the volatile compounds. The sensory evaluation showed a significant reduction in the green/leguminous attributes of pea proteins and the generation of new descriptors in the presence of yeasts. Compared to the non-fermented matrix, fermentations with LAB or LAB and yeasts led to the degradation of many off-flavor compounds. Moreover, the presence of yeasts triggered the generation of esters. Thus, fermentation by a co-culture of LAB and yeasts can be used as a powerful tool for the improvement of the sensory perception of a pea protein-based product.

Bioconversion of isoflavones glycoside to aglycone during edamame (Glycine max) soygurt production using Streptococcus thermophillus FNCC40, Lactobacillus delbrueckii FNCC41, and L. plantarum FNCC26

Abstract. Lovabyta NS, Jayus J, Nugraha AS. 2020. Bioconversion of isoflavones glycoside to aglycone during edamame (Glycine max) soygurt production using Streptococcus thermophillus FNCC40, Lactobacillus delbrueckii FNCC41, and L. plantarum FNCC26. Biodiversitas 21: 1358-1364. Due to its strong radical-scavenging and antioxidative activity, isoflavones in soybeans have received great attention for the development of functional foods. This study focused on bioconversion of isoflavones glycoside into its aglycone form of edamame green soymilk fermented with three lactic acid bacteria (LAB), i.e., S. thermophilus FNCC40, L. bulgaricus FNCC41, and L. plantarum FNCC26 to produce soygurt. Green soymilk was fermented with 6% (v/v) of LABs as a starter culture for 24 hours at 37ºC. Its antioxidative activity were measured using DPPH free radical scavenging activity method. Daidzein and genistein released during fermentation were fractionated using HPLC and detected further by LCMS to confirm the presence of these two substances. The results showed that the population density of starter culture in green soymilk reached 109 CFU/mL, and the pH decrease from 6.8 to 3.5. All LABs cultures used in the fermentation process were able to produce free aglycone, releasing more daidzein and genistein. Increasing daidzein and genistein content in soygurt results in increasing antioxidative activity. The highest antioxidative activity (IC50 = 41.01 mg/mL) was found in the soygurt fermented with S. thermophilus FNCC40. This finding indicates that S. thermophilus FNCC40, L. bulgaricus FNCC41, and L. plantarum FNCC26 are potential as an effective starter culture to produce a soygurt with good antioxidant activity.

Statistical Optimization Approaches for High Cell Biomass Production of Lactobacillus casei

Probiotic bacteria are known to treat and prevent diseases and hence promote physical and mental wellness due to their significant brain-gut relationship. The main challenge involved in probiotic commercialization is the bio processing limitation to produce high cell mass, especially with the cultivation of lactic acid bacteria which produces lactic acid as a by product. Synthesis of lactic acid by lactic acid bacteria inhibits bacterial growth, and in turn disrupts high cell mass production. Current work presents the findings for Lactobacillus casei medium optimization by response surface methodology in shake flask level. A simple medium using 4 components: lactose, soybean meal, yeast extract and magnesium sulphate has been identified to produce high cell mass than generic mediaused for probiotic cultivation, such as the MRS medium. Secondly, response surface methodology using Box-Behken Design was employed as an optimization strategy. After optimization process, the production of Lactobacillus casei biomass increased by about 164.6% recording 6.51g.L-1 compared to cell biomass obtained using initial un-optimized medium (2.46g.L-1).

Optimisation of Processing Parameters for the Preparation of Vegetable Curd from Decorticated Sesame Seeds (Sesamum indicum)

Current study aims to develop and optimise the processing parameters for the preparation of imitated curd by using vegetable milk extracted from decorticated sesame seeds (Sesamum indicum). Experiments were planned to optimise curdling process for sesame milk with respect to inoculum (1-5%), lactose (1-5%), added proteins (1-3%). It was established that total solid content in a range of 9-10%, dispersion stability with 30-45% scored well (7.8±0.2) on preferential sensory test i.e. nine-point hedonic scale. Sesame milk supplemented with 5% lactose, 1% electrolyte salt mix, 1% sucrose was subjected to fermentation (10±1.0) hrs at 35±2°C) with 5% inoculum (lactic acid bacteria culture) resulted into a vegetable curd with desired consistency (855.6±47.5 g.sec), acidity (0.57±0.02% lactic acid equivalent; LAE), flavor and overall acceptability (OAA). The Solid Not Fat (SNF) content of optimised vegetable curd was found to be 22.20±0.40%, with protein, fat and ash content as 6.70±0.06%, 6.91±0.06% and 0.92±0.01% respectively. The characteristics of vegetable milk (non-dairy) and toned milk (dairy) were well comparable on various aesthetic parameters (fluidity, color, flavor and taste). Proportional characterisation of vegetable (non-dairy) curd with dairy curd relating to its nutritional profile, color analysis, textural and rheological parameters established its similarity. Such dairy analogues may be considered as substitute to various dairy products where milk-based products are scanty or non-available.

Meat Native Lactic Acid Bacteria Capable to Inhibit Salmonella sp. and Escherichia coli.

In this study, lactic acid bacteria (LAB) strains were isolated from ground beef, and it was analyzed if they have any effect on the growth of two reference bacteria (Salmonella sp. and Escherichia coli). It was found that five isolates showed an inhibitory effect in both reference bacteria by spot at the lawn assay. These bacteria were selected to perform growth kinetics in co-culture to determine if they modify the growth parameters of the reference bacteria. Subsequently, LAB cultures and three treatments (crude extract, thermally treated and thermally treated with neutral pH) of cells free supernatants (CFS) were screened by the agar well diffusion assay. In co-culture, selected LAB altered the growth rate and reduce the maximum population of both reference bacteria. While, LAB cultures and CFS also showed antimicrobial activity, and there was no significant difference among CFS treatments. LAB isolated from ground beef showed an antimicrobial effect against the reference bacteria that could be used for meat biopreservation purposes.

Изменение микробиоты густой ржаной закваски в процессе длительного ведения

The article is devoted to the study of the microbial starter cultures preservation during the process of long-term maintenance of the sourdough in the laboratory, as well as the study of the influence of microbiota changes on the physicochemical indicators of the sourdough. The leading role in sourdough is played by lactic acid bacteria and yeast, the quality of the starter culture and bread itself largely depends on the ratio and species diversity of this microorganisms. The strains of L. paracasei / L. casei 5, L. paracasei / L. casei 63, L. plantarum 78 and the yeast C. milleri Chernorechensky are used to prepare sourdough. It was shown that the use of starter cultures of lactic acid bacteria and yeast in the technology of dense rye sourdough leads to the dominance of starter microorganisms and the sourdough production having good biotechnological characteristics already in the first phase of preparinf. However, with long-term maintenance of the sourdough, new species of lactic acid bacteria begin to dominate, which differ from those introduced in first phase. It was found that changes in the starter culture microbiota had a significant effect on the physicochemical indicators of the starter culture quality.

Biotechnological potential of new strains of lactic acid bacteria

The paper presents data on the ferment effect of acid bacteria on model protein substrates in order to determine their proteolytic potential for biotransformation of fresh meat. The proteolytic activity of new starter cultures of lactic acid bacteria was evaluated. Strains of lactic acid bacteria Lbm. casei and Lbm. curvatus, exhibiting high proteolytic activity, can be recommended for inclusion in the composition of starter cultures.

Intravaginal administration of gelatine capsules containing freeze-dried autochthonous lactobacilli: a double-blind, randomised clinical trial of safety.

Vaginal lactobacilli (LAB) in probiotic formulas constitute a promising alternative for microbiome reconstitution and for the prevention and treatment of urogenital infections. A double-blind, randomised clinical trial was conducted to assess the safety of LAB-gelatine capsules vaginally administered to healthy sexually active women. Participants were randomised into three groups: intervention A: Lactobacillus reuteri CRL1324, Lactobacillus gasseri CRL1263 and CRL1307; intervention B: Lactobacillus rhamnosus CRL1332, L. gasseri CRL1256 and CRL1320; and intervention C: placebo. In a survey and clinical evaluation, participants received a blister with 7 capsules to be administered 1 per day. A second sampling and a new survey were conducted 3-10 days after completing application. Colposcopy was performed to assess adverse effects on vaginal-cervical mucosa. Vaginal swabs were taken for Gram staining to determine the Nugent score, and obtainment of viable-cell cultures to quantify cultivable lactic acid bacteria and pathogens. The main outcomes evaluated were overall satisfaction and secondary effects, including discomfort, urogenital infection, inflammatory response or other symptoms. No significant differences were found in Nugent score or in leukocyte numbers in vaginal samples either before or after the three interventions. However, a tendency to decrease in both the Nugent score and in leukocyte numbers was observed after interventions A and B, though not after C. A significant increase in cultivable lactobacilli was determined after LAB interventions. No severe adverse events were detected. LAB-containing capsules were well tolerated by subjects, so they could be proposed as an adequate alternative to restore vaginal lactobacilli in sexually active women.

Using nitrous acid-modified de Man, Rogosa, and Sharpe medium to selectively isolate and culture lactic acid bacteria from dairy foods

Nitrous acid was used to modify traditional de Man, Rogosa, Sharpe medium to evaluate whether the addition of sodium nitrite to MRS medium could improve the rate of growth and density of various lactic acid bacteria and nontarget species. Yogurt and Cheddar cheese were inoculated with individual bacterial species followed by the recovery and enumeration of the species using the pour plate method to compare the sensitivity between nitrous acid-modified MRS (mMRS) and traditional MRS. Lactobacillus delbrueckii ssp. bulgaricus were recovered at significantly higher counts from cheese in nitrous acid mMRS than MRS, whereas no significant difference was observed for other species and food systems. Growth curves were also generated for multiple lactic acid bacteria as well as nonstarters in both mMRS and MRS to measure the selectivity of nitrous acid mMRS. The selectivity evaluation of nitrous acid mMRS demonstrated that 5 of the tested lactic acid bacterial species (Bifidobacterium longum, Streptococcus salivarius, Lactococcus lactis, Lactobacillus acidophilus, and Lactobacillus delbrueckii ssp. bulgaricus) grew to significantly higher densities more rapidly in mMRS broth than in traditional MRS. Nontarget bacteria Enterococcus faecalis and Bacillus cereus revealed a more prolific growth rate and higher optical density readings in traditional MRS compared with mMRS. It was determined that nitrous acid mMRS is a viable alternative medium for culturing selected lactic acid bacteria, and offers an improved formulation of MRS for use in standard evaluation methods and optimization of probiotic and other dairy cultures.