scholarly journals Four Types of TiO2 Reduced the Growth of Selected Lactic Acid Bacteria Strains

Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 939
Author(s):  
Ewa Baranowska-Wójcik ◽  
Klaudia Gustaw ◽  
Dominik Szwajgier ◽  
Patryk Oleszczuk ◽  
Bożena Pawlikowska-Pawlęga ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Food Additives ◽  
Gastrointestinal Microbiota ◽  
Food Grade ◽  
Tio2 Nps ◽  
Unicellular Organisms ◽  
Human Digestive Tract ◽  
The Individual ◽  
The Impact

Food-grade titanium dioxide (TiO2) containing a nanoparticle fraction (TiO2 NPs -nanoparticles) is widely used as a food additive (E171 in the EU). In recent years, it has increasingly been raising controversies as to the presence or absence of its harmful effects on the gastrointestinal microbiota. The complexity and variability of microbiota species present in the human gastrointestinal tract impede the assessment of the impact of food additives on this ecosystem. As unicellular organisms, bacteria are a very convenient research model for investigation of the toxicity of nanoparticles. We examined the effect of TiO2 (three types of food-grade E171 and one TiO2 NPs, 21 nm) on the growth of 17 strains of lactic acid bacteria colonizing the human digestive tract. Each bacterial strain was treated with TiO2 at four concentrations (60, 150, 300, and 600 mg/L TiO2). The differences in the growth of the individual strains were caused by the type and concentration of TiO2. It was shown that the growth of a majority of the analyzed strains was decreased by the application of E171 and TiO2 NPs already at the concentration of 150 and 300 mg/L. At the highest dose (600 mg/L) of the nanoparticles, the reactions of the bacteria to the different TiO2 types used in the experiment varied.

Techno-functional properties of HoPS from lactic acid bacteria of different origins as potential food additives

2021 ◽  
Vol 356 ◽  
pp. 129627
Author(s):  
René Emanuel Lobo ◽  
Theo Figueroa ◽  
Diego Navarro ◽  
María Inés Gómez ◽  
Graciela Font de Valdez ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Functional Properties ◽  
Food Additives ◽  
Different Origins ◽  
Potential Food

Food-grade lactic acid bacteria and probiotics as a potential protective tool against erythrotoxic dietary xenobiotics

2021 ◽  
Author(s):  
Paúl F. Cuevas-González ◽  
Audry Peredo-Lovillo ◽  
Cecilia Castro-López ◽  
Belinda Vallejo-Cordoba ◽  
Aarón F. González-Córdova ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Food Grade

Aroma profile and lactic acid bacteria characteristic of traditional Slovak cheese “May bryndza”

2021 ◽  
pp. 108201322110399
Author(s):  
Jana Štefániková ◽  
Július Árvay ◽  
Simona Kunová ◽  
Przemysław Łukasz Kowalczewski ◽  
Miroslava Kačániová
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Butanoic Acid ◽  
Aroma Profile ◽  
Volatile Organic ◽  
Ewe's Milk ◽  
The Impact

This paper describes the results of the characterization of a traditional Slovak cheese called “May bryndza” with regard to the profiles of volatile organic compounds and lactic acid bacteria. Samples of “May bryndza“ cheese produced solely from unpasteurized ewe's milk were collected from 4 different Slovak farms, and samples of the cheese produced from a mixture of 2 types of milk (raw ewe's and pasteurized cow's milk) were collected from 3 different Slovak industrial dairies. There were 15 compounds detected and identified by the electronic nose. The impact of the kind of milk and the kind of dairy on the aroma profile of the product was not confirmed by PCA. The compounds with the highest relative contents in samples were acetoin (2.59%–24.55%), acetic acid (6.69%–13.39%), methoxy-phenyl-oxime (4.49%–8.52%), butanoic acid (1.89%–5.67%), and 2,3-butanediol (0.98%–4.08%), which were determined with gas chromatography. A total of 1533 isolates of LAB were obtained from the “May bryndza” cheese samples. Four families, five genera, and 19 species were identified with mass spectrometry, and isolated bacteria, both from the farm and industry dairies were the most frequently found to belong to Lactococcus lactis subsp. lactis.

scholarly journals Behavior of Listeria innocua during the manufacturing and pit-ripening of Formaggio di Fossa di Sogliano PDO cheese

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Federica Giacometti ◽  
Paolo Daminelli ◽  
Laura Fiorentini ◽  
Elena Cosciani-Cunico ◽  
Paola Monastero ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Risk Mitigation ◽  
Scientific Evidence ◽  
Challenge Test ◽  
Mitigation Strategy ◽  
Listeria Innocua ◽  
Ripening Process ◽  
Protected Designation Of Origin ◽  
The Impact

Formaggio di Fossa di Sogliano is a traditional Italian Protected Designation of Origin (PDO) cheese ripened for a minimum of 5 months, with the feature of a ripening of at least 80 to at most 100 days in pits, digged into tuffaceous rocks according to medieval tradition of Italy. In this study, a challenge test using Listeria innocua as a surrogate of Listeria monocytogenes was performed, with the aim of increasing knowledge concerning the impact of the Fossa cheese process, and especially of the traditional ripening process of this PDO, on the behaviour of L. monocytogenes. Pasteurized milk was experimentally inoculated with 4.5 log CFU/mL cocktail by three L. innocua strains, and L. innocua and Mesophilic Lactic Acid Bacteria (LAB) counts as well as the evolution of temperatures, pH and aw values were monitored throughout the manufacturing and ripening processes. Throughout the ripening in maturation room a constant temperature of 8°C was observed reaching a temperature between 10 and 15.5°C during ripening into pit. In the final products data for LAB concentration, pH and aw values were roughly in accordance with literature, even if some differences were, probably due to variability of artisanal cheese productions. The numbers of L. innocua showed a slight decrease but remained stable until the end of ripening in maturation room, whereas a significant reduction of the microorganism was observed in the final product, at the end of the ripening into the pit. The findings give scientific evidence that the process of this PDO prevented the L. innocua growth, allowing us to speculate a similar behaviour of L. monocytogenes. Based on this study, the recommendation to extend as much as possible the ripening into pit (from 80 to 100 days) was provided to food business operators as a risk mitigation strategy to be implemented.

scholarly journals Functional Properties and Sustainability Improvement of Sourdough Bread by Lactic Acid Bacteria

2020 ◽  
Vol 8 (12) ◽  
pp. 1895
Author(s):  
Vera Fraberger ◽  
Claudia Ammer ◽  
Konrad J. Domig
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Functional Properties ◽  
Food Additives ◽  
Dual Culture ◽  
Bakery Products ◽  
Gaba Production ◽  
Sourdough Bread ◽  
Increasing Demand

Preventing food spoilage without the addition of chemical food additives, while increasing functional properties of wheat-based bakery products, is an increasing demand by the consumers and a challenge for the food industry. Within this study, lactic acid bacteria (LAB) isolated from sourdough were screened in vitro for the ability to utilize the typical wheat carbohydrates, for their antimicrobial and functional properties. The dual culture overlay assay revealed varying levels of inhibition against the examined fungi, with Lactiplantibacillus plantarum S4.2 and Lentilactobacillusparabuchneri S2.9 exhibiting the highest suppression against the indicator strains Fusarium graminearum MUCL43764, Aspergillus fumigatus, A. flavus MUCL11945, A. brasiliensis DSM1988, and Penicillium roqueforti DSM1079. Furthermore, the antifungal activity was shown to be attributed mainly to the activity of acids produced by LAB. The antibacillus activity was evaluated by the spot-on-the-lawn method revealing a high inhibition potential of the majority of LAB isolated from sourdough against Bacillus cereus DSM31, B. licheniformis DSM13, B. subtilis LMG7135, and B. subtilis S15.20. Furthermore, evaluating the presence of the glutamate decarboxylase gen in LAB isolates by means of PCR showed a strain dependency of a potential GABA production. Finally, due to improved functional activities, LAB isolated from sourdoughs exhibit promising characteristics for the application as natural preservatives in wheat-based bakery products.

scholarly journals Use of the alr Gene as a Food-Grade Selection Marker in Lactic Acid Bacteria

2002 ◽  
Vol 68 (11) ◽  
pp. 5663-5670 ◽  
Author(s):  
Peter A. Bron ◽  
Marcos G. Benchimol ◽  
Jolanda Lambert ◽  
Emmanuelle Palumbo ◽  
Marie Deghorain ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Competitive Inhibitor ◽  
Selection Marker ◽  
Wild Type ◽  
Gene Encoding ◽  
Food Grade ◽  
Selection For ◽  
Isogenic Mutants ◽  
Type Strains

ABSTRACT Both Lactococcus lactis and Lactobacillus plantarum contain a single alr gene, encoding an alanine racemase (EC 5.1.1.1), which catalyzes the interconversion of d-alanine and l-alanine. The alr genes of these lactic acid bacteria were investigated for their application as food-grade selection markers in a heterologous complementation approach. Since isogenic mutants of both species carrying an alr deletion (Δalr) showed auxotrophy for d-alanine, plasmids carrying a heterologous alr were constructed and could be selected, since they complemented d-alanine auxotrophy in the L. plantarum Δalr and L. lactis Δalr strains. Selection was found to be highly stringent, and plasmids were stably maintained over 200 generations of culturing. Moreover, the plasmids carrying the heterologous alr genes could be stably maintained in wild-type strains of L. plantarum and L. lactis by selection for resistance to d-cycloserine, a competitive inhibitor of Alr (600 and 200 μg/ml, respectively). In addition, a plasmid carrying the L. plantarum alr gene under control of the regulated nisA promoter was constructed to demonstrate that d-cycloserine resistance of L. lactis is linearly correlated to the alr expression level. Finally, the L. lactis alr gene controlled by the nisA promoter, together with the nisin-regulatory genes nisRK, were integrated into the chromosome of L. plantarum Δalr. The resulting strain could grow in the absence of d-alanine only when expression of the alr gene was induced with nisin.

scholarly journals The impact of lactic acid bacteria on sourdough fermentation

2005 ◽  
Vol 59 (9-10) ◽  
pp. 235-237
Author(s):  
Dragisa Savic ◽  
Natasa Jokovic
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Shelf Life ◽  
Nutritional Value ◽  
Starter Culture ◽  
Bread Quality ◽  
Bread Dough ◽  
Sourdough Bread ◽  
Biotechnological Processes ◽  
The Impact

The baking of sourdough breads represents one of the oldest biotechnological processes. Despite traditionality, sourdough bread has great potential because of its benefits. Sourdough is a mixture of flour and water that is dominated by a complex microflora composed of yeasts and lactic acid bacteria that are crucial in the preparation of bread dough. Lactic acid bacteria cause acidification by producing lactic acid that increases the shelf life of bread by preventing the growth of undesirable microorganisms and affects the nutritional value of bread by increasing the availability of minerals. In addition to these advantages, the use of sourdough fermentation also improves dough machinability, breadcrumb structure and the characteristic flavour of bread. Lactic acid bacteria in sourdough fermentation are well known representing both homofermentative and heterofermentative bacteria. They may originate from selected natural contaminants in the flour or from a starter culture containing one or more known species of lactic acid bacteria. Sourdough can be cultivated in bakeries or obtained from commercial suppliers. However, many bakeries in Europe still use spontaneously fermented sourdoughs, which have been kept metabolically active for decades by the addition of flour and water at regular intervals. The impact of lactic acid bacteria on sourdough fermentation and their influence on dough and bread quality was discussed on the basis of research and literature data.

scholarly journals Profiling and antibiotic resistance of lactic acid bacteria isolated from commercial aMasi samples

2020 ◽  
Author(s):  
◽  
Yovani Pillay
Keyword(s):  
Antibiotic Resistance ◽  
Lactic Acid ◽  
Food Safety ◽  
Lactic Acid Bacteria ◽  
South African ◽  
Bacterial Population ◽  
Principal Component ◽  
Antibiotic Resistant ◽  
Food Grade ◽  
Resistant Genes

aMasi is traditionally fermented milk that constitutes part of the South African heritage and is regarded as a supplementary staple food. Its inclusion into the South African Food Based Dietary Guidelines has led to the encouraged consumption of this product. Given the fact that aMasi is a rich source of lactic acid bacteria (LAB), such bacteria are of economic importance to the food, feed and pharmaceutical industries. The main concern regarding food safety is ability to acquire and disseminate antibiotic-resistant genes. Although LAB bility of resistance genes to human and animal opportunistic and pathogenic bacteria which could make treatment of bacterial infections more complex to treat in the future. Numerous reports globally, have documented antibiotic resistance among LAB isolated from commercial dairy and pharmaceutical products over the last decade. Therefore, the aim of this study was to determine if LAB isolated from commercial aMasi samples harbour antibiotic-resistant genes. To achieve this aim, the total bacterial population and LAB population of 10 aMasi samples were surveyed using culture-dependent techniques and the proportional prevalence of LAB to the total bacterial population were determined by using a 100% stacked-column. In all 10 samples, LAB was the predominating population ranging from 87.44% to 99.77%. A total of 30 LAB isolates were characterised after isolation and sequencing of 16S rDNA of these isolates showed that LAB were Leuconostoc pseudomesenteroides and Leuconostoc mesenteroides with two isolates being identified as Lactococcus lactis CP028160.1. The relationship between the growth of LAB and selected physicochemical properties (pH, titratable acidity, water activity (aw), moisture content, fat content and estimation of reducing sugars (lactose)) were determined using principal component analysis (PCA) and classification and regression tree (CART) to illustrate the likelihood of LAB present in aMasi samples based on LAB count and pH. From the PCA results, approximately 75.25% of variances in the data were retained by the first three principal components (PCs). The first principal component (PC1) had accounted for the highest total variance of 33.16%. PC1 increased with an increase in lactic acid % and aw, whilst it negatively correlated with LAB count, moisture % and lactose (mg/25ml lactose·H2O). The results showed an increase in LAB count with an increase in moisture % and lactose (mg/25ml lactose·H2O) whilst, LAB count had decreased with an increase in lactic acid % and aw. Moreover, pH and fat % had no effect on PC1, high LAB counts were observed for samples 6 and 7 whist low LAB counts were observed for samples 9 and 10. On the other hand, PC2 had accounted for approximately 27.53% of the total variance. PC2 increased with an increase in fat % and lactose (mg/25ml lactose·H2O), whilst it negatively correlated with LAB count and pH. It was observed that the growth of LAB had increased with an increase in pH, whilst it decreased with an increase in fat % and lactose (mg/25ml lactose·H2O). Moreover, lactic acid %, aw and moisture % had no effect on PC2. High LAB counts were observed for samples 7 and 8 and low LAB counts were observed for samples 2 and 4. Nine out of the 30 LAB isolates were selected due to these isolates having a different GenBank Accession number and were subjected to antibiotic susceptibility testing using the disc diffusion method against a total of 11 antibiotics. Most of the LAB isolates exhibited multiple resistance towards some of the most commonly used antibiotics as well as last-resort antibiotics. All the isolates showed high levels of resistance towards vancomycin, colistin sulphate, fosfomycin and pipemidic acid except for Lactococcus lactis CP028160.1 which was susceptible to vancomycin. All isolates were susceptible to tetracycline and erythromycin whilst eight out of nine isolates were susceptible to chloramphenicol with seven out of nine isolates being susceptible to ampicillin. Furthermore, the isolates had displayed intermediate resistance mainly towards kanamycin and streptomycin. The present study showed that multiple antibiotic resistance is prevalent in different species of starter culture strains, which may pose a food safety concern. LAB that exhibit phenotypic resistance to antibiotics should also be evaluated on a molecular level to monitor their resistance. The presence of such a variety of expressed AR genes in probiotic isolates is a worrying trend. The impact of the interactions of these bacteria with pathogenic strains and their transfer of these AR genes is yet to be assessed. Furthermore, antibiotic sensitivity is an important criterion in the safety assessment for the evaluation of food-grade and potential food-grade LAB.

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