Physiology of Lactic Acid Bacteria and Applications to Biotechnology

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Microbial Biotechnology".

Deadline for manuscript submissions: closed (30 April 2021) | Viewed by 58891

Special Issue Editor


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Guest Editor
Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy
Interests: metabolic engineering; biorefinery; clostridium; lactic acid fermentation; butanol
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Lactic acid bacteria (LAB) have a long history of industrial application. The most traditional uses of LAB are in food fermentation and as probiotics. Most of the worldwide industrial production of lactic acid is based on LAB fermentation. Furthermore, LAB have attracted significant interest aimed at several other biotechnological applications taking advantage of: (i) the “generally recognized as safe” status of most strains (that avoids adverse health effects on industrial production workers and consumers); (ii) their resistance to stressful industrial (e.g., pH, temperature) conditions; and (iii) the fact that they are relatively genetically tractable. Novel biotechnological uses of LAB include the production of: (i) molecules for the food industry (e.g., aromas, sweeteners, bacteriocins); (ii) nutraceuticals (e.g., GABA, bioactive peptides); (iii) therapeutic proteins and vaccines; and (iv) bulk chemicals (e.g., ethanol) and biodegradable plastic polymers (polyhydroxyalkanoates). Research in this field is very active, with more than 400 papers published in the last year.

This Special Issue aims at providing an up-to-date picture of the multiple applications of LAB to food, health, and biorefinery fields. As Guest Editor, I welcome all the contributions, including research and review articles, related to these research areas, so as to outline current frontiers and identify future challenges.

Dr. Roberto Mazzoli
Guest Editor

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Keywords

  • Lactic acid
  • Vaccine
  • Bioactive compounds
  • Ethanol
  • Exopolysaccharide
  • Sweeteners
  • Polyhydroxyalkanoate
  • Biorefinery

Published Papers (13 papers)

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Research

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13 pages, 968 KiB  
Article
PHA Production from Cheese Whey and “Scotta”: Comparison between a Consortium and a Pure Culture of Leuconostoc mesenteroides
by Francesca Bosco, Simona Cirrincione, Riccardo Carletto, Luca Marmo, Francesco Chiesa, Roberto Mazzoli and Enrica Pessione
Microorganisms 2021, 9(12), 2426; https://doi.org/10.3390/microorganisms9122426 - 25 Nov 2021
Cited by 15 | Viewed by 2700
Abstract
It is urgent to expand the market of biodegradable alternatives to oil-derived plastics owing to (i) increasingly limited oil availability/accessibility, and (ii) the dramatic impact of traditional plastics on aquatic life, the food chain, all Earth ecosystems, and ultimately, human health. Polyhydroxyalkanoates (PHAs) [...] Read more.
It is urgent to expand the market of biodegradable alternatives to oil-derived plastics owing to (i) increasingly limited oil availability/accessibility, and (ii) the dramatic impact of traditional plastics on aquatic life, the food chain, all Earth ecosystems, and ultimately, human health. Polyhydroxyalkanoates (PHAs) are promising biodegradable polymers that can be obtained through microbial fermentation of agro-industrial byproducts, e.g., milk and cheese whey. Here, the PHA-accumulating efficiency of a mixed microbial culture (MMC, derived from activated sludges) grown on dairy byproducts (cheese and scotta whey) was measured. Bioreactor tests featuring temperature and pH control showed that both scotta and pre-treated Toma cheese whey could be used for PHA production by MMC, although scotta cheese whey supported higher PHA yield and productivity. The advantages of open MMCs include their plasticity and versatility to fast changing conditions; furthermore, no growth-medium sterilization is needed prior to fermentation. However, the use of pure cultures of efficient PHA producers may support better metabolic performances. Therefore, PHA-producing strains were isolated from a MMC, leading to the satisfactory identification of two bacterial strains, Citrobacter freundii and Leuconostoc spp., whose ability to accumulate PHAs in synthetic media was confirmed. A more detailed investigation by mass spectrometry revealed that the strain was L. mesenteroides. Although the validation of L. mesenteroides potential to produce PHA through fermentation of agro-industrial byproducts requires further investigations, this is the first study reporting PHA production with the Leuconostoc genus. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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11 pages, 1697 KiB  
Article
Genotypic and Phenotypic Characterization of Highly Alkaline-Resistant Carnobacterium maltaromaticum V-Type ATPase from the Dairy Product Based on Comparative Genomics
by HyeongJin Roh and Do-Hyung Kim
Microorganisms 2021, 9(6), 1233; https://doi.org/10.3390/microorganisms9061233 - 6 Jun 2021
Cited by 4 | Viewed by 2303
Abstract
Although Carnobacterium maltaromaticum derived from dairy products has been used as a lactic acid bacterium industrially, several studies have reported potential pathogenicity and disease outbreaks. Because strains derived from diseased fish and dairy products are considered potentially virulent and beneficial, respectively, their genotypic [...] Read more.
Although Carnobacterium maltaromaticum derived from dairy products has been used as a lactic acid bacterium industrially, several studies have reported potential pathogenicity and disease outbreaks. Because strains derived from diseased fish and dairy products are considered potentially virulent and beneficial, respectively, their genotypic and phenotypic characteristics have attracted considerable attention. A genome-wide comparison of 30 genome sequences (13, 3, and 14 strains from diseased aquatic animals, dairy products, and processed food, respectively) was carried out. Additionally, one dairy and two nondairy strains were incubated in nutrient-rich (diluted liquid media) and nutrient-deficient environments (PBS) at pH 10 to compare their alkaline resistance in accordance with different nutritional environments by measuring their optical density and viable bacterial cell counts. Interestingly, only dairy strains carried 11 shared accessory genes, and 8 genes were strongly involved in the V-type ATPase gene cluster. Given that V-type ATPase contributes to resistance to alkaline pH and salts using proton motive force generated via sodium translocation across the membrane, C. maltaromaticum with a V-type ATPase might use nutrients in food under high pH. Indeed, the dairy strain carrying the V-type ATPase exhibited the highest alkaline resistance only in the nutrient-rich environment with significant upregulation of V-type ATPase expression. These results suggest that the gene cluster of V-type ATPase and increased alkaline resistance of dairy strains facilitate adaptation in the long-term ripening of alkaline dairy products. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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17 pages, 3080 KiB  
Article
Differences in Immune Response and Biochemical Parameters of Mice Fed by Kefir Milk and Lacticaseibacillus paracasei Isolated from the Kefir Grains
by Viera Karaffová, Dagmar Mudroňová, Marián Mad’ar, Gabriela Hrčková, Dominika Faixová, Soňa Gancarčíková, Zuzana Ševčíková and Radomíra Nemcová
Microorganisms 2021, 9(4), 831; https://doi.org/10.3390/microorganisms9040831 - 14 Apr 2021
Cited by 8 | Viewed by 2226
Abstract
The health benefits of kefir consumption have been well-known for hundreds of years. The objective of this study was to investigate the effect of kefir milk and the probiotic strain Lacticaseibacillus paracasei Ž2 isolated from kefir grains on the immune response and selected [...] Read more.
The health benefits of kefir consumption have been well-known for hundreds of years. The objective of this study was to investigate the effect of kefir milk and the probiotic strain Lacticaseibacillus paracasei Ž2 isolated from kefir grains on the immune response and selected parameters of the lipid and liver enzymatic profiles of mice. Mice fed with kefir milk showed significantly increased phagocytic activity and percentages of B cells in the blood and increased gene expression for mucins and percentages of CD8+ lymphocytes in the gut. By applying kefir, we achieved a significant reduction in serum LDL cholesterol and an LDL/HDL ratio that favored an increase in HDL cholesterol. Regarding the hepatic enzymes, in particular a significant reduction in ALT activity was observed. L. paracasei Ž2 alone stimulated the immune response more markedly compared with kefir milk. Regarding the systemic level, we observed increases in the proportion of all T cells (CD3+), CD4+ lymphocytes and the ratio of CD4+:CD8+ cells, and regarding the local intestinal level we noted a significant increase in gene expression for mucins (MUC-1 and MUC-2) and IgA. Moreover, we confirmed the formation of a biofilm on the surface of the forestomach only after the application of L. paracasei Ž2 alone, but not after kefir administration. The results confirmed the hypothesis that the final effect of the probiotic does not correspond with the effect of the individual strain but is the result of mutual interactions of the microorganisms presented in a preparation, and therefore in the case of multi-strain probiotics, in vivo testing of the complex preparation is necessary. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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15 pages, 3347 KiB  
Article
Lectin-Mediated Binding of Engineered Lactococcus lactis to Cancer Cells
by Tina Vida Plavec, Abida Zahirović, Petra Zadravec, Jerica Sabotič and Aleš Berlec
Microorganisms 2021, 9(2), 223; https://doi.org/10.3390/microorganisms9020223 - 22 Jan 2021
Cited by 5 | Viewed by 2534
Abstract
Lectins have been increasingly utilized as carriers for targeted drug delivery based on their specific binding to glycans located on mammalian cells. This study employed two lectins, B subunit of bacterial Shiga holotoxin (Stx1B) and fungal Clitocybe nebularis lectin (CNL), for surface display [...] Read more.
Lectins have been increasingly utilized as carriers for targeted drug delivery based on their specific binding to glycans located on mammalian cells. This study employed two lectins, B subunit of bacterial Shiga holotoxin (Stx1B) and fungal Clitocybe nebularis lectin (CNL), for surface display on the lactic acid bacterium Lactococcus lactis. The specific adhesion of these engineered, lectin-displaying L. lactis to cancer cells was evaluated. The expression and surface display of both lectins on L. lactis were demonstrated by western blotting and flow cytometry, respectively. MTS assays revealed that recombinant Stx1B had no effect on Caco-2 cell viability at concentrations of ≤25 µg/mL, whereas CNL was non-toxic even at relatively high concentrations of ≤250 µg/mL. Stx1B bound to Caco-2, HT-29 and HeLa cells after 1 h of incubation. CNL bound to Caco-2 cells and recognized several glycoproteins in HT-29 and Caco-2 cell homogenates of which a 70 kDa protein predominated. Confocal microscopy revealed adhesion of Stx1B-displaying L. lactis to HeLa, Caco-2, and, to a lesser extent, HT-29 cells; CNL-displaying L. lactis showed a relatively similar level of adherence to HT-29 and Caco-2 cells. Thus, lectin-displaying L. lactis might serve as a carrier in targeted drug delivery when coupled to a therapeutic moiety. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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12 pages, 2609 KiB  
Article
Environmental Conditions Affecting GABA Production in Lactococcus lactis NCDO 2118
by Valérie Laroute, Roberto Mazzoli, Pascal Loubière, Enrica Pessione and Muriel Cocaign-Bousquet
Microorganisms 2021, 9(1), 122; https://doi.org/10.3390/microorganisms9010122 - 7 Jan 2021
Cited by 19 | Viewed by 2831
Abstract
GABA (γ-aminobutyric acid) production has been widely described as an adaptive response to abiotic stress, allowing bacteria to survive in harsh environments. This work aimed to clarify and understand the relationship between GABA production and bacterial growth conditions, with particular reference to osmolarity. [...] Read more.
GABA (γ-aminobutyric acid) production has been widely described as an adaptive response to abiotic stress, allowing bacteria to survive in harsh environments. This work aimed to clarify and understand the relationship between GABA production and bacterial growth conditions, with particular reference to osmolarity. For this purpose, Lactococcus lactis NCDO 2118, a GABA-producing strain, was grown in glucose-supplemented chemically defined medium containing 34 mM L-glutamic acid, and different concentrations of salts (chloride, sulfate or phosphate ions) or polyols (sorbitol, glycerol). Unexpectedly, our data demonstrated that GABA production was not directly related to osmolarity. Chloride ions were the most significant factor influencing GABA yield in response to acidic stress while sulfate ions did not enhance GABA production. We demonstrated that the addition of chloride ions increased the glutamic acid decarboxylase (GAD) synthesis and the expression of the gadBC genes. Finally, under fed-batch conditions in a complex medium supplemented with 0.3 M NaCl and after a pH shift to 4.6, L. lactis NCDO 2118 was able to produce up to 413 mM GABA from 441 mM L-glutamic acid after only 56 h of culture, revealing the potential of L. lactis strains for intensive production of this bioactive molecule. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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19 pages, 1360 KiB  
Article
Antimicrobial Potential of Food Lactic Acid Bacteria: Bioactive Peptide Decrypting from Caseins and Bacteriocin Production
by Stefano Nebbia, Cristina Lamberti, Giuliana Lo Bianco, Simona Cirrincione, Valerie Laroute, Muriel Cocaign-Bousquet, Laura Cavallarin, Maria Gabriella Giuffrida and Enrica Pessione
Microorganisms 2021, 9(1), 65; https://doi.org/10.3390/microorganisms9010065 - 29 Dec 2020
Cited by 24 | Viewed by 4855
Abstract
Lactic acid bacteria (LAB) potential in the food industry and in the biotechnological sector is a well-established interest. LAB potential in counteracting especially food-borne infections has received growing attention, but despite being a road full of promises is yet poorly explored. Furthermore, the [...] Read more.
Lactic acid bacteria (LAB) potential in the food industry and in the biotechnological sector is a well-established interest. LAB potential in counteracting especially food-borne infections has received growing attention, but despite being a road full of promises is yet poorly explored. Furthermore, the ability of LAB to produce antimicrobial compounds, both by ribosomal synthesis and by decrypting them from proteins, is of high value when considering the growing impact of multidrug resistant strains. The antimicrobial potential of 14 food-derived lactic acid bacteria strains has been investigated in this study. Among them, four strains were able to counteract Listeria monocytogenes growth: Lactococcus lactis SN12 and L. lactis SN17 by high lactic acid production, whereas L. lactis 41FLL3 and Lactobacillus sakei I151 by Nisin Z and Sakacin P production, respectively. Strains Lactococcus lactis MG1363, Lactobacillus rhamnosus 17D10 and Lactobacillus helveticus 4D5 were tested and selected for their potential attitude to hydrolyze caseins. All the strains were able to release bioactive peptides with already known antimicrobial, antihypertensive and opioid activities. These features render these strains or their bioactive molecules suitable for use in food as biocontrol agents, or as nutraceutical supplements to treat mild disorders such as moderate hypertension and children insomnia. These results highlight once again that LAB potential in ensuring food safety, food nutraceutical value and ultimately in favoring human health is still underexplored and underexploited. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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15 pages, 457 KiB  
Article
Probiotic and Antioxidant Potential of Lactobacillus reuteriLR12 and Lactobacillus lactisLL10 Isolated from Pineapple Puree and Quality Analysis of Pineapple-Flavored Goat Milk Yoghurt during Storage
by Naif Abdullah Al-Dhabi, Mariadhas Valan Arasu, Ponnuswamy Vijayaraghavan, Galal Ali Esmail, Veeramuthu Duraipandiyan, Young Ock Kim, Hyungsuk Kim and Hak-Jae Kim
Microorganisms 2020, 8(10), 1461; https://doi.org/10.3390/microorganisms8101461 - 23 Sep 2020
Cited by 53 | Viewed by 4513
Abstract
In recent years, studies have focused on the therapeutic properties of probiotics to eliminate pathogenic microorganisms associated with various diseases. Lactobacilli are important probiotics groups that have been found to possess many health-promoting activities. This study was carried out to isolate LactobacillusreuteriLR12 [...] Read more.
In recent years, studies have focused on the therapeutic properties of probiotics to eliminate pathogenic microorganisms associated with various diseases. Lactobacilli are important probiotics groups that have been found to possess many health-promoting activities. This study was carried out to isolate LactobacillusreuteriLR12 and L. lactisLL10 from pineapple puree. The invitro analysis to evaluate probiotic characteristics of the isolated bacteria included survival in bile and acid tolerance. The cell-free supernatant of L. reuteri LR12 was effective against various pathogenic bacteria and fungi compared with L. lactisLL10. These two bacterial strains have strong anti-biofilm activity (100%) against Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus. The bacterial strains exhibited adhesion properties to HT-29 cells (human colorectal adenocarcinoma). These bacteria showed DPPH- (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free radical scavenging activity, scavenging of hydroxyl radical activity, superoxide radical scavenging activity, and reducing power activity in the range of 72% ± 3%to 89.3% ± 1.7%, 64% ± 2.7%to 66.8% ± 1.5%, 59.8% ± 4.1% to 63.8% ± 2.1%, and 60.4% ± 1.8%to 66.1% ± 3.3%, respectively. Pineapple puree was used as the starter culture with milk for 2 days for yogurt preparation. Pineapple puree increased flavor and showed the physicochemical properties of yogurt. The finding of the sensory evaluation revealed no significant change compared with the control, except the appearance of yogurt. These findings show that Lactobacilli and pineapple puree have potential use in various probiotic preparations for the fermentation industry. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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20 pages, 1264 KiB  
Article
Teff Type-I Sourdough to Produce Gluten-Free Muffin
by Cinzia Dingeo, Graziana Difonzo, Vito Michele Paradiso, Carlo Giuseppe Rizzello and Erica Pontonio
Microorganisms 2020, 8(8), 1149; https://doi.org/10.3390/microorganisms8081149 - 29 Jul 2020
Cited by 12 | Viewed by 3412
Abstract
The increasing number of persons following a gluten-free (GF) diet and the need for healthy and natural products are forcing researchers and industries to provide gluten-free products with high nutritional value. Here, a biotechnological approach combining the use of teff flour and type-I [...] Read more.
The increasing number of persons following a gluten-free (GF) diet and the need for healthy and natural products are forcing researchers and industries to provide gluten-free products with high nutritional value. Here, a biotechnological approach combining the use of teff flour and type-I sourdough has been proposed to produce GF muffins with nutritional benefits. Teff-sourdough was prepared and propagated following the traditional daily refreshment procedure until the biochemical stability was achieved. The sourdough, dominated by Lactiplantibacillus plantarum, Limosilactobacillus fermentum and Saccharomyces cerevisiae strains, was used to produce muffins at three different levels (up to 15%, wt/wt) of fortification, achieving several positive effects on the nutritional properties of the products. The use of teff flour led to high content of fiber (>3 g/100 g) and proteins (>6 g/100 g) in muffins achieving the nutritional requirements for the healthy claims “source of fiber” and “rich in protein”. Thanks to their metabolic traits, sourdough lactic acid bacteria caused the increase of the total free amino acids (TFAA, up to 1000 mg/kg, final concentration) and phytic acid decrease (50% lower than control), which positively affect the nutritional properties of the products. Besides, high in vitro protein digestibility (IVPD, 79%) and low starch hydrolysis rate (HI, 52%) characterized the fortified muffins. Muffins also presented high in vitro antioxidant (56%) and mold-inhibitory activities, potentially contributing to an extended shelf-life of the products. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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17 pages, 4258 KiB  
Article
Characterization of Weissella koreensis SK Isolated from Kimchi Fermented at Low Temperature (around 0 °C) Based on Complete Genome Sequence and Corresponding Phenotype
by So Yeong Mun and Hae Choon Chang
Microorganisms 2020, 8(8), 1147; https://doi.org/10.3390/microorganisms8081147 - 29 Jul 2020
Cited by 24 | Viewed by 3930
Abstract
This study identified lactic acid bacteria (LAB) that play a major role in kimchi fermented at low temperature, and investigated the safety and functionality of the LAB via biologic and genomic analyses for its potential use as a starter culture or probiotic. Fifty [...] Read more.
This study identified lactic acid bacteria (LAB) that play a major role in kimchi fermented at low temperature, and investigated the safety and functionality of the LAB via biologic and genomic analyses for its potential use as a starter culture or probiotic. Fifty LAB were isolated from 45 kimchi samples fermented at −1.5~0 °C for 2~3 months. Weissella koreensis strains were determined as the dominant LAB in all kimchi samples. One strain, W. koreensis SK, was selected and its phenotypic and genomic features characterized. The complete genome of W. koreensis SK contains one circular chromosome and plasmid. W. koreensis SK grew well under mesophilic and psychrophilic conditions. W. koreensis SK was found to ferment several carbohydrates and utilize an alternative carbon source, the amino acid arginine, to obtain energy. Supplementation with arginine improved cell growth and resulted in high production of ornithine. The arginine deiminase pathway of W. koreensis SK was encoded in a cluster of four genes (arcA-arcB-arcD-arcC). No virulence traits were identified in the genomic and phenotypic analyses. The results indicate that W. koreensis SK may be a promising starter culture for fermented vegetables or fruits at low temperature as well as a probiotic candidate. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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21 pages, 8736 KiB  
Article
Selection of Exopolysaccharide-Producing Lactobacillus Plantarum (Lactiplantibacillus Plantarum) Isolated from Algerian Fermented Foods for the Manufacture of Skim-Milk Fermented Products
by Nadia Bachtarzi, Immacolata Speciale, Karima Kharroub, Cristina De Castro, Lorena Ruiz and Patricia Ruas-Madiedo
Microorganisms 2020, 8(8), 1101; https://doi.org/10.3390/microorganisms8081101 - 23 Jul 2020
Cited by 17 | Viewed by 4788
Abstract
The exopolysaccharide (EPS)-producing Lactobacillus plantarum (renamed as Lactiplantibacillus plantarum) LBIO1, LBIO14 and LBIO28 strains, isolated from fermented dairy products typical from Algeria, were characterized to evaluate the impact of the polymers in milk fermentations. Their genomes revealed the presence of two complete [...] Read more.
The exopolysaccharide (EPS)-producing Lactobacillus plantarum (renamed as Lactiplantibacillus plantarum) LBIO1, LBIO14 and LBIO28 strains, isolated from fermented dairy products typical from Algeria, were characterized to evaluate the impact of the polymers in milk fermentations. Their genomes revealed the presence of two complete eps clusters of the four described for the reference strain WCFS1. Besides, the three strains presented identical sequences of eps3 and eps4 clusters, but LBIO1 and LBIO28 harbour three genes belonging to eps2 which are absent in the LBIO14 genome. The EPS purified from fermented skim-milks manufactured with the strains showed identical nuclear magnetic resonance (1H-NMR) and size exclusion chromatography coupled with a multiangle laser light scattering detector (SEC-MALLS) profiles for polymers LBIO1 and LBIO28, whereas LBIO14 EPS was different due to the lack of the high-molecular weight (HMW)-EPS and the absence of specific monosaccharide’s peaks in the anomeric region of its proton NMR spectrum. The presence of the HMW-EPS correlated with optimal sensorial-physical characteristics of the fermented skim-milks (ropy phenotype). Their microstructures, studied by confocal scanning laser microscopy (CSLM), also showed differences in the organization of the casein-network and the distribution of the bacteria inside this matrix. Therefore, the strain LBIO1 can be proposed for the manufacture of dairy products that require high whey retention capability, whereas LBIO28 could be applied to increase the viscosity. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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13 pages, 1593 KiB  
Article
Probiotic Potential and Technological Properties of Bacteriocinogenic Lactococcus lactis Subsp. Lactis UTNGt28 from a Native Amazonian Fruit as a Yogurt Starter Culture
by Gabriela N. Tenea and Jimena Suárez
Microorganisms 2020, 8(5), 733; https://doi.org/10.3390/microorganisms8050733 - 14 May 2020
Cited by 15 | Viewed by 2643
Abstract
A native Lactococcus lactis subsp. lactis UTNGt28 (GenBank accession no: MG675576.1) isolated from Amazonian fruit of the tropical Caimitillo (Chrysophyllum oliviforme) tree and the commercial strain Lactococcus lactis subsp lactis ATCC11454 (LacAT) were targeted ex vitro in whole milk in combination [...] Read more.
A native Lactococcus lactis subsp. lactis UTNGt28 (GenBank accession no: MG675576.1) isolated from Amazonian fruit of the tropical Caimitillo (Chrysophyllum oliviforme) tree and the commercial strain Lactococcus lactis subsp lactis ATCC11454 (LacAT) were targeted ex vitro in whole milk in combination with Streptococcus thermophilus ATCC19258 to obtain a fermented probiotic beverage. Concomitant with cell viability determination during storage (28 days), the pH, titratable acidity, syneresis, protein and fat were evaluated. The results indicated that neither UTNGt28 nor LacAT displayed a high capacity to ferment whole milk and survive during storage; a statistically significant difference (p < 0.05) in cell viability was registered for UTNGt28 compared with LacAT when inoculated alone or in combination with S. thermophilus. A principal component analysis showed a clear difference between the yogurt formulations at day 1 and 28 of storage. The PC 1 explained 46.8% of the total variance (day 28), was loaded in the negative (−) direction with titratable acidity (% lactic acid), while the PC 2 explained 22.5% (day 1) with pH. PC 1 was loaded in the positive (+) direction with pH, cell viability, syneresis, fat and protein. Overall results indicated that UTNGt28 has the technological properties for further development of a new probiotic product. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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Review

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24 pages, 4177 KiB  
Review
Glutamate Decarboxylase from Lactic Acid Bacteria—A Key Enzyme in GABA Synthesis
by Ida Bagus Agung Yogeswara, Suppasil Maneerat and Dietmar Haltrich
Microorganisms 2020, 8(12), 1923; https://doi.org/10.3390/microorganisms8121923 - 3 Dec 2020
Cited by 87 | Viewed by 12962
Abstract
Glutamate decarboxylase (l-glutamate-1-carboxylase, GAD; EC 4.1.1.15) is a pyridoxal-5’-phosphate-dependent enzyme that catalyzes the irreversible α-decarboxylation of l-glutamic acid to γ-aminobutyric acid (GABA) and CO2. The enzyme is widely distributed in eukaryotes as well as prokaryotes, where it—together with [...] Read more.
Glutamate decarboxylase (l-glutamate-1-carboxylase, GAD; EC 4.1.1.15) is a pyridoxal-5’-phosphate-dependent enzyme that catalyzes the irreversible α-decarboxylation of l-glutamic acid to γ-aminobutyric acid (GABA) and CO2. The enzyme is widely distributed in eukaryotes as well as prokaryotes, where it—together with its reaction product GABA—fulfils very different physiological functions. The occurrence of gad genes encoding GAD has been shown for many microorganisms, and GABA-producing lactic acid bacteria (LAB) have been a focus of research during recent years. A wide range of traditional foods produced by fermentation based on LAB offer the potential of providing new functional food products enriched with GABA that may offer certain health-benefits. Different GAD enzymes and genes from several strains of LAB have been isolated and characterized recently. GABA-producing LAB, the biochemical properties of their GAD enzymes, and possible applications are reviewed here. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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33 pages, 491 KiB  
Review
Update of Probiotics in Human World: A Nonstop Source of Benefactions till the End of Time
by Mohamed Zommiti, Marc G. J. Feuilloley and Nathalie Connil
Microorganisms 2020, 8(12), 1907; https://doi.org/10.3390/microorganisms8121907 - 30 Nov 2020
Cited by 115 | Viewed by 7933
Abstract
Lactic acid bacteria (LAB) are known for their biotechnological potential. Moreover, LAB are distinguished by amazing criteria: Adjusting the intestinal environment, inhibiting pathogenic microbes in the gastrointestinal tract, ability to reduce pathogen adhesion activity, improving the balance of the microbiota inside the intestine, [...] Read more.
Lactic acid bacteria (LAB) are known for their biotechnological potential. Moreover, LAB are distinguished by amazing criteria: Adjusting the intestinal environment, inhibiting pathogenic microbes in the gastrointestinal tract, ability to reduce pathogen adhesion activity, improving the balance of the microbiota inside the intestine, capabilities of regulating intestinal mucosal immunity, and maintaining intestinal barrier function. The escalating number of research and studies about beneficial microorganisms and their impact on promoting health has attracted a big interest in the last decades. Since antiquity, various based fermented products of different kinds have been utilized as potential probiotic products. Nevertheless, the current upsurge in consumers’ interest in bioalternatives has opened new horizons for the probiotic field in terms of research and development. The present review aims at shedding light on the world of probiotics, a continuous story of astonishing success in various fields, in particular, the biomedical sector and pharmaceutical industry, as well as to display the importance of probiotics and their therapeutic potential in purpose to compete for sturdy pathogens and to struggle against diseases and acute infections. Shadows and future trends of probiotics use are also discussed. Full article
(This article belongs to the Special Issue Physiology of Lactic Acid Bacteria and Applications to Biotechnology)
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