Evaluation of Probiotic Potential of Bacteriocinogenic Lactic Acid Bacteria Strains Isolated from Meat Products

In this study, the probiotic potential of five bacteriocin-producing lactic acid bacteria (LAB) strains, isolated from meat products, was investigated. They were presumptively identified as Lactococcus lactis subsp. cremoris CTC 204 and CTC 483, L. lactis subsp. hordinae CTC 484, and Lactobacillus plantarum CTC 368 and CTC 469 according to morphological, biochemical, and physiological characteristics. Analysis of genetic variability (random amplified polymorphic (RAPD)-PCR) and whole-cell proteins (SDS-PAGE) revealed similarity between Lactobacillus strains and variability among Lactococcus strains. The evaluation of the probiotic potential showed that the five LAB strains were tolerant to pH 2.0, and only strain CTC 469 was tolerant to the lowest concentration of the bile salts evaluated (0.1%). All strains showed survival or growth ability at 4, 25, and 37 °C, and tolerance at ??20 °C. Although strain CTC 204 in TSB Broth supplemented with MgSO₄ showed the highest intensity of biofilm production, this compound was produced by all of them. The safety assessment showed that no thermonuclease, hemolytic, or gelatinase activities were detected. All strains were resistant to erythromycin and sensitive to amoxicillin and phenoxymethylpenicillin; furthermore, CTC 204 was resistant to chloramphenicol, CTC 368 and CTC 469 to chloramphenicol and vancomycin, CTC 483 to tetracycline and vancomycin, and CTC 484 to clindamycin and chloramphenicol. The evaluated strains showed biogenic amine production; the lowest levels were produced by CTC 204 and CTC 368 strains. It was concluded that CTC 204 and CTC 368 strains have the greatest potential for becoming probiotics.     

Probiotic Properties of Lactic Acid Bacteria Isolated from Water-Buffalo Mozzarella Cheese

This study evaluated the probiotic properties (stability at different pH values and bile salt concentration, auto-aggregation and co-aggregation, survival in the presence of antibiotics and commercial drugs, study of β-galactosidase production, evaluation of the presence of genes encoding MapA and Mub adhesion proteins and EF-Tu elongation factor, and the presence of genes encoding virulence factor) of four LAB strains (Lactobacillus casei SJRP35, Leuconostoc citreum SJRP44, Lactobacillus delbrueckii subsp. bulgaricus SJRP57 and Leuconostoc mesenteroides subsp. mesenteroides SJRP58) which produced antimicrobial substances (antimicrobial peptides). The strains survived the simulated GIT modeled in MRS broth, whole and skim milk. In addition, auto-aggregation and the cell surface hydrophobicity of all strains were high, and various degrees of co-aggregation were observed with indicator strains. All strains presented low resistance to several antibiotics and survived in the presence of commercial drugs. Only the strain SJRP44 did not produce the β-galactosidase enzyme. Moreover, the strain SJRP57 did not show the presence of any genes encoding virulence factors; however, the strain SJRP35 presented vancomycin resistance and adhesion of collagen genes, the strain SJRP44 harbored the ornithine decarboxylase gene and the strain SJRP58 generated positive results for aggregation substance and histidine decarboxylase genes. In conclusion, the strain SJRP57 was considered the best candidate as probiotic cultures for further in vivo studies and functional food products development.     

Role of Broiler Carcasses and Processing Plant Air in Contamination of Modified-Atmosphere-Packaged Broiler Products with Psychrotrophic Lactic Acid Bacteria

Some psychrotrophic lactic acid bacteria (LAB) are specific meat spoilage organisms in modified-atmosphere-packaged (MAP), cold-stored meat products. To determine if incoming broilers or the production plant environment is a source of spoilage LAB, a total of 86, 122, and 447 LAB isolates from broiler carcasses, production plant air, and MAP broiler products, respectively, were characterized using a library of HindIII restriction fragment length polymorphism (RFLP) patterns of the 16 and 23S rRNA genes as operational taxonomic units in numerical analyses. Six hundred thirteen LAB isolates from the total of 655 clustered in 29 groups considered to be species specific. Sixty-four percent of product isolates clustered either with Carnobacterium divergens or with Carnobacterium maltaromaticum type strains. The third major product-associated cluster (17% of isolates) was formed by unknown LAB. Representative strains from these three clusters were analyzed for the phylogeny of their 16S rRNA genes. This analysis verified that the two largest RFLP clusters consisted of carnobacteria and showed that the unknown LAB group consisted of Lactococcus spp. No product-associated LAB were detected in broiler carcasses sampled at the beginning of slaughter, whereas carnobacteria and lactococci, along with some other specific meat spoilage LAB, were recovered from processing plant air at many sites. This study reveals that incoming broiler chickens are not major sources of psychrotrophic spoilage LAB, whereas the detection of these organisms from the air of the processing environment highlights the role of processing facilities as sources of LAB contamination.     

Psychrotrophic Bacteria Isolated from a Constantly Warm Tropical Environment

Psychrotrophic bacteria are known to occur in temperate, constantly cold, and artificially cooled environments. This is the first report of their occurrence in a constantly warm (ca. 24°–35°C) tropical environment. Soil samples taken from two sites along the southeastern coastal zone of Jamaica yielded growth of psychotrophic bacteria after 3–4 weeks of enrichment culture in 1/30 strength tryptic soy broth, 20 mg L⁻¹ cycloheximide at 2°C. Growth of individual isolates at 2°C was confirmed. Isolates include aerobic and fermentative Gram-negative rods and sporeforming (Bacillus sp.) and non-sporeforming (Aureobacterium sp.) Gram-positive rods. We determined the effect of temperature on growth rate in four isolates. Strain Y1 has an unusually wide temperature range for growth, 2°–44°C, resembling that of Listeria monocytogenes. In strain R1 the optimum temperature for growth occurred unusually near the maximum temperature for growth. Strains R2 and Y2 displayed cardinal temperatures typical of known psychotrophs but appear to have evolved enhanced growth potential near the optimum temperature in response to a constantly warm environment. Received: 30 April 1997 / Accepted: 9 August 1997     

A Study of 5920 Strains of Psychrotrophic Bacteria Isolated from Chickens

The psychrotrotrophic flora of chicken carcases in 3 different industrial processing plants has been studied. The micro-organisms, 5920 strains, were placed in 4 categories (arranged in decreasing order of the number of isolates): (1), Pseudomonas and Achromobacter (Acineto-bacter) ; (2) Flavobacterium, Corynebacterium and yeasts; (3), Aeromonas and Entero-bacteriaceae; (4), lactic acid bacteria, Micrococcaceae and Bacillus . Different types of strains belonging to these groups are described and the importance of each is discussed with reference to the observations of other authors. The proteolytic action of 1717 of the 5920 isolates was studied.     

Probiotic Features of Lactic Acid Bacteria Isolated from a Diverse Pool of Traditional Greek Dairy Products Regarding Specific Strain-Host Interactions

Probiotics and Antimicrobial Proteins - The increased consumers’ interest on the positive role of food in wellbeing and health underscores the need to determine new probiotic microorganisms....     

Cholesterol Assimilation by Lactic Acid Bacteria and Bifidobacteria Isolated from the Human Gut

The objective of this study was to evaluate the effect of human gut-derived lactic acid bacteria and bifidobacteria on cholesterol levels in vitro. Continuous cultures inoculated with fecal material from healthy human volunteers with media supplemented with cholesterol and bile acids were used to enrich for potential cholesterol assimilators among the indigenous bacterial populations. Seven potential probiotics were found: Lactobacillus fermentum strains F53 and KC5b, Bifidobacterium infantis ATCC 15697, Streptococcus bovis ATCC 43143, Enterococcus durans DSM 20633, Enterococcus gallinarum, and Enterococcus faecalis. A comparative evaluation regarding the in vitro cholesterol reduction abilities of these strains along with commercial probiotics was undertaken. The degree of acid and bile tolerance of strains was also evaluated. The human isolate L. fermentum KC5b was able to maintain viability for 2 h at pH 2 and to grow in a medium with 4,000 mg of bile acids per liter. This strain was also able to remove a maximum of 14.8 mg of cholesterol per g (dry weight) of cells from the culture medium and therefore was regarded as a candidate probiotic.     

Sources of Psychrotrophic Bacteria on Meat at the Abattoir

An export abattoir was examined to determine the sources and types of psychrotrophic bacteria which gain access to meat. Gram negative psychrotrophs were recovered from the hides, from structural and work surfaces within the abattoir, and from carcasses and meat at all stages of processing. Microbacterium thermosphactum was recovered intermittently at all sampling sites. Psychrotrophic and total counts and the incidence of M. thermosphactum on carcasses and meat increased during processing through the abattoir. Structural and work surfaces may be as important as the hide as sources of bacterial contaminants on meat. Seasonal variation was observed in psychrotrophic counts which correlated positively with rainfall and negatively with temperature.     

Tyrosinase Inhibitory and Anti-oxidative Effects of Lactic Acid Bacteria Isolated from Dairy Cow Feces

Overproduction and accumulation of melanin cause a number of skin diseases. The inhibitors of tyrosinase are important for the treatment of skin diseases associated with hyper-pigmentation after UV exposure and application in cosmetics for whitening and depigmentation. Reactive oxygen species (ROS) including hydrogen peroxide are generated by chemical substances and metabolic intermediates and cause various diseases including cancer and heart diseases. We have isolated four different lactic acid bacteria (LAB) strains from dairy cow feces and investigated the tyrosinase inhibition and anti-oxidative effects of culture filtrates prepared from the isolated bacteria, which are designated as EA3, EB2, PC2, and PD3. To investigate optimal culture conditions isolated LAB strains, the measurements of tyrosinase inhibitory and anti-oxidative activities were performed. The results of tyrosinase inhibitory activities revealed that Enterococcus sp. EA3 showed about 65% at culture conditions (14 h, 30 °C, pH 8, and 0% NaCl), Enterococcus sp. EB2 about 65% at culture conditions (12 h, 30 °C, pH 9, and 0% NaCl), Pediococcus sp. PC2 about 80% at culture conditions (20 h, 30 °C, pH 6, and 0% NaCl), and Pediococcus sp. PD3 about 80% at culture conditions (20 h, 30 °C, pH 8, and 0% NaCl), respectively. In addition, anti-oxidative activities against four different LAB strains showed approximately more than 30% at optimal conditions for the measurements of tyrosinase inhibitory activities. From the results, we have suggested that the isolated four LAB strains could be useful for a potential agent for developing anti-oxidants and tyrosinase inhibitors.     

The Screening of Hydrogen Peroxide-Producing Lactic Acid Bacteria and Their Application to Inactivating Psychrotrophic Food-Borne Pathogens

Lactic acid bacteria were isolated from various food samples and evaluated for hydrogen peroxide (H₂O₂) production. Cells suspended in 0.5% (wt/vol) glucose plus 0.5% (wt/vol) lactate (pH 7.0) were incubated for 5 h at 37°C under aeration. Among 193 strains, 27 strains accumulated 201-300 ppm H₂O₂, and 4 strains accumulated more than 301 ppm H₂O₂ in the cell suspensions. Among the 9 high-level H₂O₂-producing strains, 8 strains were identified as Lactococcus lactis subsp. lactis. The cell-free filtrate from Lc. lactis subsp. lactis AI 62, which contained approximately 350 ppm H₂O₂, was evaluated for antimicrobial activity against Enterococcus faecalis, Ent. faecium, enterotoxigenic Escherichia coli, Listeria ivanovii, Staphylococcus aureus, Yersinia enterocolitica, and Aeromonas hydrophila. After 1 h incubation at 30°C in the cell-free filtrate, the initial viable cell counts of the target bacteria (5.53–6.00 log cfu/mL) were reduced by 0.12-5.00 log units, except in the case of enterococci. The sensitivity varied with the bacterial species and pH. The enterococci were resistant to the treatment. Our results show that H₂O₂ accumulated by lactic acid bacteria in a cell suspension is very effective in reducing the viable cell count of food-borne pathogens.Received: 7 October 2002 / Accepted: 4 November 2002     

Lactic Acid Bacteria Isolated from Bovine Mammary Microbiota: Potential Allies against Bovine Mastitis

Bovine mastitis is a costly disease in dairy cattle worldwide. As of yet, the control of bovine mastitis is mostly based on prevention by thorough hygienic procedures during milking. Additional strategies include vaccination and utilization of antibiotics. Despite these measures, mastitis is not fully under control, thus prompting the need for alternative strategies. The goal of this study was to isolate autochthonous lactic acid bacteria (LAB) from bovine mammary microbiota that exhibit beneficial properties that could be used for mastitis prevention and/or treatment. Sampling of the teat canal led to the isolation of 165 isolates, among which a selection of ten non-redundant LAB strains belonging to the genera Lactobacillus and Lactococcus were further characterized with regard to several properties: surface properties (hydrophobicity, autoaggregation); inhibition potential of three main mastitis pathogens, Staphylococcus aureus, Escherichia coli and Streptococcus uberis; colonization capacities of bovine mammary epithelial cells (bMEC); and immunomodulation properties. Three strains, Lactobacillus brevis 1595 and 1597 and Lactobacillus plantarum 1610, showed high colonization capacities and a medium surface hydrophobicity. These strains are good candidates to compete with pathogens for mammary gland colonization. Moreover, nine strains exhibited anti-inflammatory properties, as illustrated by the lower IL-8 secretion by E. coli-stimulated bMEC in the presence of these LAB. Full genome sequencing of five candidate strains allowed to check for undesirable genetic elements such as antibiotic resistance genes and to identify potential bacterial determinants involved in the beneficial properties. This large screening of beneficial properties while checking for undesirable genetic markers allowed the selection of promising candidate LAB strains from bovine mammary microbiota for the prevention and/or treatment of bovine mastitis.     

Potentials of Exopolysaccharides from Lactic Acid Bacteria

Recent research in the area of importance of microbes has revealed the immense industrial potential of exopolysaccharides and their derivative oligosaccharides from lactic acid bacteria. However, due to lack of adequate technological knowledge, the exopolysaccharides have remained largely under exploited. In the present review, the enormous potentials of different types of exopolysaccharides from lactic acid bacteria are described. This also summarizes the recent advances in the applications of exopolysaccharides, certain problems associated with their commercial production and the remedies.     

An Alternative Biotechnological Tool for Magnesite Enrichment: Lactic Acid Bacteria Isolated from Soil

Abstract

Calcium carbonate (CaCO₃) is found in different polymorph structures such as aragonite, vaterite, and calcite. The most common and stable form of CaCO₃, calcite, which is abundant in sedimentary rocks as magnesite ore. Magnesite has application areas in many industrial fields including paper, pharmaceutical and refractory materials. Magnesite is theoretically formulated MgCO₃, but contains many impurities (silicium, iron, and also calcite), that limits its usability and applicability. In this research, we aimed to investigate the decalcification possibility of the raw magnesite material through application of Enterococcus feacelis (EF) with CaCO₃ dissolution ability. The exact mechanism of CaCO₃ dissolution was investigated by carbonic anhydrase enzyme assay and HPLC analysis of organic acids produced by EF. Consequently, EF reduced the amount of CaCO₃ from 2.94% to 0.49% which means a reduction (≈83.33%) in the rate of CaCO₃ percentage. As a result of the experiments, it was observed that different organic acids produced by bacteria reacted with CaCO₃ and removed the lime of magnesite ore. The bacteria used in the study did not show any pathogenic properties in rats, thus, it can be used safely for the industrial applications.     

猪源乳酸菌产乳酸及其抑菌特性研究

研究了5株(L1、12、L3、L5和L7)分离自仔猪肠道的乳酸菌的产乳酸能力及抑菌特性。结果表明：L5菌株产乳酸的速度最快,培养液中乳酸含量最高,L5菌株培养液pH值的下降速度最快,终末pH值最低,而L1菌株产乳酸的速度最慢,培养液乳酸含量最低。5株乳酸菌对大肠杆菌K88、K99、987P、O141和大肠杆菌E1及金黄色葡萄球菌均有不同程度的抑制作用;排除酸的影响后仍有22％～53％抑菌效果;经热处理后保持有92％以上的抑菌效果;蛋白酶处理后保持85％以上的抑菌效果。     

Characterization and Transfer of Antibiotic Resistance in Lactic Acid Bacteria from Fermented Food Products

The study provides phenotypic and molecular analyses of the antibiotic resistance in lactic acid bacteria (LAB) from fermented foods in Xi'an, China. LAB strains (n = 84) belonging to 16 species of Lactobacillus (n = 73), and Streptococcus thermophilus (n = 11) were isolated and identified by sequencing their 16S rRNA gene. All strains were susceptible to ampicillin, bacitracin, and cefsulodin, and intrinsically resistant to nalidixic acid, kanamycin, and vancomycin (except L. bulgaricus, L. acidophilus, and S. thermophilus, which were susceptible to vancomycin). Some strains had acquired resistance for penicillin (n = 2), erythromycin (n = 9), clindamycin (n = 5), and tetracycline (n = 14), while resistance to gentamycin, ciprofloxacin, streptomycin, and chloramphenicol was species dependent. Minimum inhibitory concentrations presented in this study will help to review microbiological breakpoints for some of the species of Lactobacillus. The erm(B) gene was detected from two strains of each of L. fermentum and L. vaginalis, and one strain of each of L. plantarum, L. salivarius, L. acidophilus, L. animalis, and S. thermophilus. The tet genes were identified from 12 strains of lactobacilli from traditional foods. This is the first time, the authors identified tet(S) gene from L. brevis and L. kefiri. The erm(B) gene from L. fermentum NWL24 and L. salivarius NWL33, and tet(M) gene from L. plantarum NWL22 and L. brevis NWL59 were successfully transferred to Enterococcus faecalis 181 by filter mating. It was concluded that acquired antibiotic resistance is well dispersed in fermented food products in Xi'an, China and its transferability to other genera should be monitored closely.     

一组鸡源乳酸菌产乳酸及其耐受特性研究*

研究了12株（K9、D17、C1、C12、D11、D14、C2、D9、K6、C21、D1和D7）分离自肉鸡肠道的乳酸菌的产乳酸能力及其中3株产酸能力强的菌株的耐受特性。12株乳酸菌产乳酸结果表明：12h内,K6产乳酸速度最快,其次为K9和C1,24h时,D17乳酸浓度最高,48h时C1终乳酸浓度最高。K9、D17和C1的耐受试验结果表明：C1菌株耐酸能力最强,pH2时,C1菌株培养3h后还能检测到活菌,D17和K9菌株培养1h后就已经检测不到活菌。在胆盐浓度0．08％-0．40％范围内,C1、D17和K9均有一定的耐受能力,随着胆盐浓度的升高,C1、D17和K9的存活数呈现缓慢的下降趋势。3株菌中D17耐热能力最强,经80％处理后仍有10^4.9／mL存活数,而K9和C1已检测不到活菌;C1对热最敏感,65℃处理后存活数由10^8／mL降为10^3／mL。     

Investigation of Lactic Acid Bacteria Isolated from Giant Panda Feces for Potential Probiotics In Vitro

Probiotics and Antimicrobial Proteins - The present study aimed to isolate an optimal lactic acid bacterial strain from the feces of healthy giant pandas. The strain exhibited good stability at low...     

Characterization,Identification and Application of Lactic Acid Bacteria Isolated from Forage Paddy Rice Silage

There has been growing interest to develop forage rice as a new feed resource for livestock. This study was to characterize the natural population of lactic acid bacteria (LAB) and select potentially excellent strains for paddy rice silage preparation in China. One hundred and twenty-six strains were isolated and screened from paddy rice silage prepared using a small-scale fermentation system, and ninety-nine of these isolates were considered to be LAB based on their Gram-positive and catalase-negative morphology and the production of most of their metabolic products as lactic acid. These isolates were divided into eight groups (A-H) on the basis of their morphological and biochemical characteristics. The Group A to H strains were identified as Lactobacillus (L.) plantarum subsp. plantarum (species ratio: 8.1%), L. casei (5.1%), Leuconostoc (Ln.) pseudomesenteroides (11.1%), Pediococcus (P.) pentosaceus (24.2%), Enterococcus (E.) mundtii (12.1%), Lactococcus (Lc.) garvieae (15.2%), E. faecium (9.1%) and Lc. lactis subsp. lactis (15.2%) based on sequence analyses of their 16S rRNA and recA genes. P. pentosaceus was the most abundant member of the LAB population in the paddy rice silage. A selected strain, namely L. casei R 465, was found to be able to grow under low pH conditions and to improve the silage quality with low pH and a relatively high content of lactic acid. This study demonstrated that forage paddy rice silage contains abundant LAB species and its silage can be well preserved by inoculation with LAB, and that strain R 465 can be a potentially excellent inoculant for paddy rice silage.     

Antibacterial and Antibiofilm Activity of Lactic Acid Bacteria Isolated from Traditional Artisanal Milk Cheese from Northeast China Against Enteropathogenic Bacteria

The present study aims to investigate the probiotic properties of novel strains of lactic acid bacteria isolated from traditional artisanal milk cheese from Northeast China and to explore their antibacterial activity against enteropathogenic bacteria. Of the 321 isolates, 86 exhibited survival in low pH, resistance to pancreatin, and tolerance to bile salts; of these, 12 inhibited the growth of more than seven enteropathogenic bacteria and exhibited antibiofilm activities against Staphylococcus aureus CMCC26003 and/or Escherichia coli CVCC230. Based on 16S ribosomal RNA sequence analysis, the 12 isolates were assigned to Lactobacillus plantarum (7), Lactobacillus helveticus (3), Pediococcus acidilactici (1), and Enterococcus faecium (1) species. In addition, 5 of the 12 strains were susceptible to most of the tested antibiotics. Furthermore, four strains with sensitivity to antibiotics showed significantly high levels of hydrophobicity similar to or better than the reference strain Lactobacillus rhamnosus GG. Moreover, three strains were confirmed safe through non-hemolytic activities and bacterial translocation. Overall, the selected Lact. plantarum 27053 and 27172 and Lact. helveticus 27058 strains can be considered potential probiotic strains and candidates for further application in functional food and prevention or treatment of gastrointestinal diseases.     

乳酸菌肽聚糖部分免疫增强作用的研究

以小鼠为实验材料研究了肽聚糖部分免疫学活性,结果表明:小鼠腹腔注射肽聚糖后,相比对照组而言, Z8、Z17肽聚糖组巨噬细胞(MΦ)吞噬率、吞噬指数都明显提高,血清溶菌酶活性显著增强,统计学分析差异极显著(P＜0．01)。肽聚糖对鸡新城疫疫苗免疫增强效果的观察表明,与对照组相比,Z8、Z17肽聚糖组能明显提高新城疫抗体水平,并使抗体高峰水平维持时间延长。同时动物实验也表明,两个肽聚糖组间活性差异不显著,没有特异性。