Stress Physiology of Lactic Acid Bacteria Papadimitriou, Konstantinos; Alegría, Ángel; Bron, Peter A ...
Microbiology and molecular biology reviews,
09/2016, Volume:
80, Issue:
3
Journal Article
Peer reviewed
Open access
Lactic acid bacteria (LAB) are important starter, commensal, or pathogenic microorganisms. The stress physiology of LAB has been studied in depth for over 2 decades, fueled mostly by the ...technological implications of LAB robustness in the food industry. Survival of probiotic LAB in the host and the potential relatedness of LAB virulence to their stress resilience have intensified interest in the field. Thus, a wealth of information concerning stress responses exists today for strains as diverse as starter (e.g., Lactococcus lactis), probiotic (e.g., several Lactobacillus spp.), and pathogenic (e.g., Enterococcus and Streptococcus spp.) LAB. Here we present the state of the art for LAB stress behavior. We describe the multitude of stresses that LAB are confronted with, and we present the experimental context used to study the stress responses of LAB, focusing on adaptation, habituation, and cross-protection as well as on self-induced multistress resistance in stationary phase, biofilms, and dormancy. We also consider stress responses at the population and single-cell levels. Subsequently, we concentrate on the stress defense mechanisms that have been reported to date, grouping them according to their direct participation in preserving cell energy, defending macromolecules, and protecting the cell envelope. Stress-induced responses of probiotic LAB and commensal/pathogenic LAB are highlighted separately due to the complexity of the peculiar multistress conditions to which these bacteria are subjected in their hosts. Induction of prophages under environmental stresses is then discussed. Finally, we present systems-based strategies to characterize the "stressome" of LAB and to engineer new food-related and probiotic LAB with improved stress tolerance.
The present study aims to evaluate the probiotic potential of lactic acid bacteria (LAB) isolated from naturally fermented olives and select candidates to be used as probiotic starters for the ...improvement of the traditional fermentation process and the production of newly added value functional foods. Seventy one (71) lactic acid bacterial strains (17 Leuconostoc mesenteroides, 1 Ln. pseudomesenteroides, 13 Lactobacillus plantarum, 37 Lb. pentosus, 1 Lb. paraplantarum, and 2 Lb. paracasei subsp. paracasei) isolated from table olives were screened for their probiotic potential. Lb. rhamnosus GG and Lb. casei Shirota were used as reference strains. The in vitro tests included survival in simulated gastrointestinal tract conditions, antimicrobial activity (against Listeria monocytogenes, Salmonella Enteritidis, Escherichia coli O157:H7), Caco-2 surface adhesion, resistance to 9 antibiotics and haemolytic activity. Three (3) Lb. pentosus, 4 Lb. plantarum and 2 Lb. paracasei subsp. paracasei strains demonstrated the highest final population (>8 log cfu/ml) after 3 h of exposure at low pH. The majority of the tested strains were resistant to bile salts even after 4 h of exposure, while 5 Lb. plantarum and 7 Lb. pentosus strains exhibited partial bile salt hydrolase activity. None of the strains inhibited the growth of the pathogens tested. Variable efficiency to adhere to Caco-2 cells was observed. This was the same regarding strains' susceptibility towards different antibiotics. None of the strains exhibited β-haemolytic activity. As a whole, 4 strains of Lb. pentosus, 3 strains of Lb. plantarum and 2 strains of Lb. paracasei subsp. paracasei were found to possess desirable in vitro probiotic properties similar to or even better than the reference probiotic strains Lb. casei Shirota and Lb. rhamnosus GG. These strains are good candidates for further investigation both with in vivo studies to elucidate their potential health benefits and in olive fermentation processes to assess their technological performance as novel probiotic starters.
► The in vitro probiotic potential of 71 lactic acid bacteria from olives was studied. ► The strains Lactobacillus casei Shirota and Lb. rhamnosus GG were used as reference. ► 4 Lb. pentosus, 3 Lb. plantarum and 2 Lb. paracasei strains showed probiotic potential. ► These strains can be used as novel probiotic starters in table olive fermentation. ► Further in vivo studies are necessary to elucidate their potential health benefits.
is a major starter for the dairy industry with great economic importance. In this study we analyzed 23 fully sequenced genomes of
to highlight novel aspects of the evolution, biology and ...technological properties of this species. Pan/core genome analysis revealed that the species has an important number of conserved genes and that the pan genome is probably going to be closed soon. According to whole genome phylogeny and average nucleotide identity (ANI) analysis, most
strains were grouped in two major clusters (i.e., clusters A and B). More specifically, cluster A includes strains with chromosomes above 1.83 Mbp, while cluster B includes chromosomes below this threshold. This observation suggests that strains belonging to the two clusters may be differentiated by gene gain or gene loss events. Furthermore, certain strains of cluster A could be further subdivided in subgroups, i.e., subgroup I (ASCC 1275, DGCC 7710, KLDS SM, MN-BM-A02, and ND07), II (MN-BM-A01 and MN-ZLW-002), III (LMD-9 and SMQ-301), and IV (APC151 and ND03). In cluster B certain strains formed one distinct subgroup, i.e., subgroup I (CNRZ1066, CS8, EPS, and S9). Clusters and subgroups observed for
indicate the existence of lineages within the species, an observation which was further supported to a variable degree by the distribution and/or the architecture of several genomic traits. These would include exopolysaccharide (EPS) gene clusters, Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs)-CRISPR associated (Cas) systems, as well as restriction-modification (R-M) systems and genomic islands (GIs). Of note, the histidine biosynthetic cluster was found present in all cluster A strains (plus strain NCTC12958
) but was absent from all strains in cluster B. Other loci related to lactose/galactose catabolism and urea metabolism, aminopeptidases, the majority of amino acid and peptide transporters, as well as amino acid biosynthetic pathways were found to be conserved in all strains suggesting their central role for the species. Our study highlights the necessity of sequencing and analyzing more
complete genomes to further elucidate important aspects of strain diversity within this starter culture that may be related to its application in the dairy industry.
Vitis vinifera L. cv. Agiorgitiko is one of the most popular indigenous wine grape varieties in Greece, cultivated almost exclusively in the Nemea Protected Designation of Origin (PDO) zone. Here, ...the microbiota of soil, grapes, and wine, during controlled (CF) and spontaneous (SF) fermentations of Agiorgitko cv. from three vineyards in the PDO Nemea zone were explored, using both classical microbiological analysis and metataxonomics to get evidence about the microbial terroir of the PDO Nemea zone. The classical microbiological analysis revealed higher total mesophilic counts in soil, while in both grapes and wine samples, yeasts prevailed. Lactic acid bacteria and acetic acid bacteria counts were lower in grapes compared to wine and soil. Metataxonomic analysis revealed that, regarding yeasts/fungi, genera Fusarium, Sarea, and Alternaria dominated in soil; Aureobasidium, Cladosporium, and Penicillium in grapes; Saccharomyces in wine during CF; and Hanseniaspora and Saccharomyces in wine during SF. Regarding bacteria, genera Skermanella, Acidobacterium, and Ohtaekwangia dominated in soil, Sphingomonas, Micrococcus, and Rubrobacter in grapes, while Tatumella, Alcanivorax, and Komagateibacter in wine during both CF and SF. Finally, the factors that significantly influence the microbiota of soil, grapes, and wine samples were assessed, and potential microbial biomarkers were identified for the first time in a Greek grape variety.
This study aimed to examine the potential antiviral activity of lactic acid bacteria (LAB) using animal and human intestinal and macrophage cell line models of non tumor origin. To this end, LAB ...strains selected on the basis of previous
in vitro trials were co-incubated with cell line monolayers, which were subsequently challenged with rotavirus (RV) and transmissible gastroenteritis virus (TGEV). In order to elucidate the possible mechanism responsible for the antiviral activity, the induction of reactive oxygen species (ROS) release as well as the attachment ability of LAB on the cell lines was investigated. Various strains were found to exhibit moderate to complete monolayer protection against viral RV or TGEV disruption. Highest protection effects were recorded with the known probiotics
Lactobacillus rhamnosus GG and
Lactobacillus casei Shirota against both RV and TGEV, while notable antiviral activity was also attributed to
Enterococcus faecium PCK38,
Lactobacillus fermentum ACA-DC179,
Lactobacillus pentosus PCA227 and
Lactobacillus plantarum PCA236 and PCS22
, depending on the cell line and virus combination used. A variable increase (of up to 50%) on the release of NO
− and H
2O
2 (ROS) was obtained when LAB strains were co-incubated with the cell lines, but the results were found to be LAB strain and cell line specific, apart from a small number of strains which were able to induce strong ROS release in more than one cell line. In contrast, the ability of the examined LAB strains to attach to the cell line monolayers was LAB strain but not cell line specific. Highest attachment ability was observed with
L. plantarum ACA-DC 146,
L. paracasei subsp.
tolerans ACA-DC 4037 and
E. faecium PCD71. Clear indications on the nature of the antiviral effect were evident only in the case of the
L. casei Shirota against TGEV and with
L. plantarum PCA236 againt both RV and TGEV. In the rest of the cases, each interaction was LAB-cell line–virus specific, barring general conclusions. However, it is probable that more than one mechanism is involved in the antiviral effect described here. Further investigations are required to elucidate the underlying mode of action and to develop a cell line model as a system for selection of probiotic strains suited for farm animal applications.
Twenty-nine
Lactobacillus strains of dairy origin were examined in vitro for their probiotic potential. Only a few strains were able to survive at pH 1 or in the presence of pepsin, while all were ...unaffected by pH 3, pancreatin and bile salts. Strains exhibited variable bile salt hydrolase activity. None was haemolytic. The majority of strains were resistant to vancomycin and teicoplanin, but sensitive to chloramphenicol and tetracycline. A few strains were able to adhere to Caco-2 cells. Although no bacteriocin activity was detected in vitro
, strains
L. casei Shirota ACA-DC 6002,
L. plantarum ACA-DC 146 and
L. paracasei subsp.
tolerans ACA-DC 4037 were able to inhibit the adhesion of
Escherichia coli and
Salmonella typhimurium to Caco-2 cells. They also induced the secretion of pro- and anti-inflammatory cytokines by human peripheral blood mononuclear cells. These three strains were therefore found, in vitro, to possess desirable probiotic properties.
One of the main lactic acid bacterial species found in the kefir grain ecosystem worldwide is Lactobacillus kefiranofaciens, exhibiting strong auto-aggregation capacity and, therefore, being involved ...in the mechanism of grain formation. Its occurrence and dominance in kefir grains of various types of milk and geographical origins have been verified by culture-dependent and independent approaches using multiple growth media and regions of the 16S rRNA gene, respectively, highlighting the importance of their combination for its taxonomic identification. L. kefiranofaciens comprises two subspecies, namely kefiranofaciens and kefirgranum, but only the first one is responsible for the production of kefiran, the water-soluble polysaccharide, which is a basic component of the kefir grain and famous for its technological as well as health-promoting properties. L. kefiranofaciens, although very demanding concerning its growth conditions, can be involved in mechanisms affecting intestinal health, immunomodulation, control of blood lipid levels, hypertension, antimicrobial action, and protection against diabetes and tumors. These valuable bio-functional properties place it among the most exquisite candidates for probiotic use as a starter culture in the production of health-beneficial dairy foods, such as the kefir beverage.
Cheese is characterized by a rich and complex microbiota that plays a vital role during both production and ripening, contributing significantly to the safety, quality, and sensory characteristics of ...the final product. In this context, it is vital to explore the microbiota composition and understand its dynamics and evolution during cheese manufacturing and ripening. Application of high-throughput DNA sequencing technologies have facilitated the more accurate identification of the cheese microbiome, detailed study of its potential functionality, and its contribution to the development of specific organoleptic properties. These technologies include amplicon sequencing, whole-metagenome shotgun sequencing, metatranscriptomics, and, most recently, metabolomics. In recent years, however, the application of multiple meta-omics approaches along with data integration analysis, which was enabled by advanced computational and bioinformatics tools, paved the way to better comprehension of the cheese ripening process, revealing significant associations between the cheese microbiota and metabolites, as well as their impact on cheese flavor and quality.
belongs to the
clade and it is found in a variety of fermented foods. Strain ACA-DC 1533 was isolated from traditional Greek Kopanisti cheese and among the available
genomes it is the only one with a ...fully sequenced chromosome.
strains exhibited a high degree of conservation at the genome level. Investigation of the distribution of prophages and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) among the three strains suggests the potential existence of lineages within the species. Based on the presence/absence patterns of these genomic traits, strain ACA-DC 1533 seems to be more related to strain JCM 10692
than strain KCTC 13900. Interestingly, strains ACA-DC 1533 and JCM 10692
which lack CRISPRs, carry two similar prophages. In contrast, strain KCTC 13900 seems to have acquired immunity to these prophages according to the sequences of spacers in its CRISPRs. Nonetheless, strain KCTC 13900 has a prophage that is absent from strains ACA-DC 1533 and JCM 10692
. Furthermore, comparative genomic analysis was performed among
ACA-DC 1533,
UCC118 and
ATCC 27782. The chromosomes of the three species lack long-range synteny. Important differences were also determined in the number of glycobiome related proteins, proteolytic enzymes, transporters, insertion sequences and regulatory proteins. Moreover, no obvious genomic traits supporting a probiotic potential of
ACA-DC 1533 were detected when compared to the probiotic
UCC118. However, the existence of more than one glycine-betaine transporter within the genome of ACA-DC 1533 may explain the ability of
to grow in fermented foods containing high salt concentrations. Finally,
analysis of the
ACA-DC 1533 genome revealed pathways that could underpin the production of major volatile compounds during the catabolism of amino acids that may contribute to the typical piquant flavors of Kopanisti cheese.
Kopanisti is a Greek PDO cheese, which is traditionally produced by the addition of an amount of over-mature Kopanisti, called Mana Kopanisti, to initiate cheese ripening. The aim of this study was ...the production of four types of Kopanisti cheese (A-D) using pasteurized cow milk, and a combination of the following starters/adjuncts in order to test their ability to be used in Kopanisti cheese production: A:
subsp.
and
, B:
and
/Mana Kopanisti, C:
and
/
and
, D:
and
. Throughout production and ripening, classical microbiological, metataxonomics and physicochemical analyses were employed, while the final products (Day 35) were subjected to sensory analysis as well. Most interestingly, beta-diversity analysis of the metataxonomics data revealed the clusters constructed among the Kopanisti types based on the different inoculation schemes. On day 35, Kopanisti A-C types clustered together due to their similar 16S microbiota, while Kopanisti D was highly differentiated. On the contrary, ITS data clustered Kopanisti B and C together, while Kopanisti A and D were grouped seperately. Finally, based on the sensory evaluation, Kopanisti C appeared to have the most suitable bacteria cocktail for the Kopanisti cheese production. Therefore, not only were the conventional starters used, but also the
and
strains could be used in a standardized Kopanisti cheese production that could lead to final products of high quality and safety.
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