Selection of potentially probiotic Kluyveromyces lactis for the fermentation of cheese whey–based beverage

This work aimed to assess the probiotic potential of different Kluyveromyces lactis strains isolated from Canastra cheese and to produce a fermented cheese whey beverage added to beetroot juice using the selected strain. Kluyveromyces lactis strains were tested for their resistance to the passage through the simulated gastrointestinal tract, adhesion properties, and functional effects such as inhibition of enteric pathogens, short-chain fatty acids (SCFA) production, and β-galactosidase activity. The selected strain was used to produce a fermented cheese whey beverage added to beetroot juice in different proportions. The produced beverages were characterized using HPLC for sugars, Folin-Ciocalteu for total phenolic content, DPPH for antioxidant activity, and GC-MS for volatiles compounds. Except B51, all strains showed viability above 75% after exposure to the simulated gastric and duodenal juices. The aggregation rates were above 84% in 24 h. Only B9 and C16 strains presented hydrophobicity above 60%. The highest B9 β-galactosidase activities were 2.17 U/g and 2.21 U/g for pH 7 and 9, respectively. The B9 SCFA profile was similar to that found for Saccharomyces bourllardi. The fermented cheese whey beverages presented phenolic content ranging from 102.75 to 291.61 μg EAG/mL and inhibition of DPPH ranging from 38.69 to 81.02% after 21 days of storage, besides being lactose free. Esters and acetates were the most abundant compounds. Kluyveromyces lactis B9 presented interesting results as a potential probiotic yeast. The produced beverages allowed the delivery of K. lactis B9 through innovative product with functional properties.     

Lactic acid bacteria isolated from fermented flour of finger millet,its probiotic attributes and bioactive properties

This study aims to isolate and identify lactic acid bacteria from fermented flour of selected finger millet varieties grown in Sri Lanka and to evaluate their probiotic attributes and bioactive properties in vitro. Fifteen lactic acid bacteria were isolated from three varieties of fermented finger millet flour namely ravi, raavana and oshadha. These isolates were screened for phenotypical and biochemical characteristics. The selected isolates were identified by 16 S rRNA sequencing as Bacillus cereus (five strains), Streptococcus lutetiensis, Lactobacillus plantarum, Lactobacillus fermentum (two strains), Brevibacillus borstelensis, Paenibacillus species, Lactococcus lactis subspecies lactis, Enterococcus faecium, Pediococcus acidilactici, and Enterococcus lactis, and their partial sequences were deposited in GenBank. Among them, five isolates including two isolates, L. plantarum MF405176.1 and L. fermentum MF033346.1 isolated from ravi; two isolates, L. lactis MF480428.1 and E. faecium MF480431.1 isolated from raavana; and P. acidilactici MF480434.1 isolated from oshadha varieties respectively, exhibited in vitro safety attributes and could tolerate acid, gastric juice, bile, salt, phenol, and temperature under simulated gastric conditions, and also were susceptible to antibiotics tested. Further, they demonstrated bactericidal activity against both drug-sensitive and multidrug-resistant pathogens. Among the selected isolates, L. plantarum MF405176.1 demonstrated highest hydrophobicity and adhesion to both colon colorectal adenocarcinoma and colon colorectal carcinoma cell lines. L. lactis subspecies lactis MF480428.1 exhibited the highest auto-aggregation and 2, 2, diphenyl-1-pricrylhydrazyl free radical scavenging activity. P. acidilactici MF480434.1 demonstrated the lowest IC50 values against HCT-116 and HT-29 cells. None of the LAB isolates could assimilate > 10% cholesterol in vitro.     

Genetic screening of functional properties of lactic acid bacteria in a fermented pearl millet slurry and in the metagenome of fermented starchy foods

Lactic acid bacteria (LAB) (n = 152) in African pearl millet slurries and in the metagenomes of amylaceous fermented foods were investigated by screening 33 genes involved in probiotic and nutritional functions. All isolates belonged to six species of the genera Pediococcus and Lactobacillus, and Lactobacillus fermentum was the dominant species. We screened the isolates for the abilities to survive passage through the gastrointestinal tract and to synthesize folate and riboflavin. The isolates were also tested in vitro for their abilities to survive exposure to bile salts and to survive at pH 2. Because the ability to hydrolyze starch confers an ecological advantage on LAB that grow in starchy matrixes as well as improving the nutritional properties of the gruels, we screened for genes involved in starch metabolism. The results showed that genes with the potential ability to survive passage through the gastrointestinal tract were widely distributed among isolates and metagenomes, whereas in vitro tests showed that only a limited set of isolates, mainly those belonging to L. fermentum, could tolerate a low pH. In contrast, the wide distribution of genes associated with bile salt tolerance, in particular bsh, is consistent with the high frequency of tolerance to bile salts observed. Genetic screening revealed a potential for folate and riboflavin synthesis in both isolates and metagenomes, as well as high variability among genes related to starch metabolism. Genetic screening of isolates and metagenomes from fermented foods is thus a promising approach for assessing the functional potential of food microbiotas.     

An in vitro study of the probiotic potential of a bile-salt-hydrolyzing Lactobacillus fermentum strain,and determination of its cholesterol-lowering properties

This study evaluated the use of a bile-salt-hydrolyzing Lactobacillus fermentum strain as a probiotic with potential hypocholesterolemic properties. The effect of L. fermentum on representative microbial populations and overall metabolic activity of the human intestinal microbiota was investigated using a three-stage continuous culture system. Also, the use of galactooligosaccharides as a prebiotic to enhance growth and/or activity of the Lactobacillus strain was evaluated. Administration of L. fermentum resulted in a decrease in the overall bifidobacterial population (ca. 1 log unit). In the in vitro system, no significant changes were observed in the total bacterial, Lactobacillus, Bacteroides, and clostridial populations through L. fermentum supplementation. Acetate production decreased by 9 to 27%, while the propionate and butyrate concentrations increased considerably (50 to 90% and 52 to 157%, respectively). A general, although lesser, increase in the production of lactate was observed with the administration of the L. fermentum strain. Supplementation of the prebiotic to the culture medium did not cause statistically significant changes in either the numbers or the activity of the microbiota, although an increase in the butyrate production was seen (29 to 39%). Results from this in vitro study suggest that L. fermentum KC5b is a candidate probiotic which may affect cholesterol metabolism. The short-chain fatty acid concentrations, specifically the molar proportion of propionate and/or bile salt deconjugation, are probably the major mechanism involved in the purported cholesterol-lowering properties of this strain.     

In vitro evaluation of the fermentation characteristics of the carbohydrate fractions of hulless barley and other cereals in the gastrointestinal tract of pigs

An in vitro model was used to study the fermentation characteristics of carbohydrate fractions of hulless barley (hB), in comparison to hulled barley (HB), hulled oat and oat groats (OG) in the pig intestine. For this purpose, 6 hulless barley cultivars (hB), varying in β-glucan content (36–99 g/kg DM), were compared to 3 HB cultivars, 2 oat groat samples (OG), 3 oat varieties and a reference sample of wheat. The residue of a pepsin–pancreatin hydrolysis was incubated in a buffered mineral solution inoculated with pig faeces. Gas production, proportional to the amount of fermented carbohydrates, was measured for 48 h and kinetics modelled. The fermented solution was subsequently analyzed for microbial production of short-chain fatty acids (SCFA) and ammonia. In vitro dry matter degradability varied according to ingredient (P<0.001). Higher values were observed for OG, ranging from 0.88 to 0.99 as compared to oat, hB and HB, for which degradability ranged from 0.63 to 0.73, 0.68 to 0.80 and 0.69 to 0.71, respectively. A “cereal type” effect (P<0.05) was observed on fermentation kinetics parameters. Total gas production was higher (P<0.05) with hB (224 ml/g DM incubated) than with HB and oat (188 and 55 ml/g DM incubated, respectively). No difference was observed between hB cultivars (P>0.05) for total gas production but differences (P<0.001) were found for lag time and the fractional rate of degradation. Hulless barley cultivar CDC Fibar (waxy starch) and CDC McGwire (normal starch) started to ferment sooner (lag time of 0.7 and 0.9 h, respectively) than SH99250 (high amylose starch; 1.7 h). The fractional rate of degradation was similar in both hB and OG (0.15/h on average), which was higher than that of HB (0.12/h). The production of SCFA was also higher (P<0.05) with hB (6.1 mmol/g DM incubated, on average) than with HB and oat (4.9 and 2.9 mmol/g DM incubated, respectively). Similar trends were found for SCFA production expressed per g fermented carbohydrates, with higher butyrate and lower acetate ratio. In contrast, oat fermentation generated higher (P<0.05) ammonia concentration (1.4 mmol/g DM incubated, on average) than hB (1.0 mmol/g DM incubated). In summary, hulless barleys, irrespective of cultivar type had higher in vitro fermentability and produced more SCFA and less ammonia than hulled barley and oat. Thus, hulless barleys have a better potential to be used in pig nutrition to manipulate the fermentation activity in the intestine of pigs.     

In vitro fermentation characteristics of selected glucose-based polymers by canine and human fecal bacteria

This research evaluated fermentation characteristics (short-chain fatty acid [SCFA] production, pH, and gas production) resulting from fermentation of glucose-based carbohydrates using canine (n = 3) and human (n = 3) fecal inoculum. Substrates included lyophilized canine ileal digesta containing maltodextrin, gamma-cyclodextrin, high molecular weight (MW) pullulan (MW 100000), or low MW pullulan (MW 6300) obtained from an in vivo experiment. Fermentation for 6 and 10 h with human fecal microflora resulted in higher gas and SCFA production than did canine fecal microflora. High MW pullulan fermentation resulted in the highest (p < 0.05) gas production and lowest (p < 0.05) pH for both dogs and humans. Total SCFA production was highest (p < 0.05) for low MW pullulan fermented by canine microflora, and for gamma-cyclodextrin, high MW pullulan, and low MW pullulan fermented by human microflora. Differences were noted in fermentation characteristics of substrates present in ileal digesta.     

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.     

Polyphasic study of the spatial distribution of microorganisms in Mexican pozol, a fermented maize dough, demonstrates the need for cultivation-independent methods to investigate traditional fermentations

The distribution of microorganisms in pozol balls, a fermented maize dough, was investigated by a polyphasic approach in which we used both culture-dependent and culture-independent methods, including microbial enumeration, fermentation product analysis, quantification of microbial taxa with 16S rRNA-targeted oligonucleotide probes, determination of microbial fingerprints by denaturing gradient gel electrophoresis (DGGE), and 16S ribosomal DNA gene sequencing. Our results demonstrate that DGGE fingerprinting and rRNA quantification should allow workers to precisely and rapidly characterize the microbial assemblage in a spontaneous lactic acid fermented food. Lactic acid bacteria (LAB) accounted for 90 to 97% of the total active microflora; no streptococci were isolated, although members of the genus Streptococcus accounted for 25 to 50% of the microflora. Lactobacillus plantarum and Lactobacillus fermentum, together with members of the genera Leuconostoc and Weissella, were the other dominant organisms. The overall activity was more important at the periphery of a ball, where eucaryotes, enterobacteria, and bacterial exopolysacharide producers developed. Our results also showed that the metabolism of heterofermentative LAB was influenced in situ by the distribution of the LAB in the pozol ball, whereas homolactic fermentation was controlled primarily by sugar limitation. We propose that starch is first degraded by amylases from LAB and that the resulting sugars, together with the lactate produced, allow a secondary flora to develop in the presence of oxygen. Our results strongly suggest that cultivation-independent methods should be used to study traditional fermented foods.     

Lactic acid bacteria and yeasts associated with gowé production from sorghum in Bénin

AIMS: To identify the dominant micro-organisms involved in the production of gowé, a fermented beverage, and to select the most appropriate species for starter culture development. METHODS AND RESULTS: Samples of sorghum gowé produced twice at three different production sites were taken at different fermentation times. DNA amplification by internal transcribed spacer-polymerase chain reaction of 288 lactic acid bacteria (LAB) isolates and 16S rRNA gene sequencing of selected strains revealed that the dominant LAB responsible for gowé fermentation were Lactobacillus fermentum, Weissella confusa, Lactobacillus mucosae, Pediococcus acidilactici, Pediococcus pentosaceus and Weissella kimchii. DNA from 200 strains of yeasts was amplified and the D1/D2 domain of the 26S rRNA gene was sequenced for selected isolates, revealing that the yeasts species were Kluyveromyces marxianus, Pichia anomala, Candida krusei and Candida tropicalis. CONCLUSIONS: Gowé processing is characterized by a mixed fermentation dominated by Lact. fermentum, W. confusa and Ped. acidilactici for the LAB and by K. marxianus, P. anomala and C. krusei for the yeasts. SIGNIFICANCE AND IMPACT OF THE STUDY: The diversity of the LAB and yeasts identified offers new opportunities for technology upgrading and products development in gowé production. The identified species can be used as possible starter for a controlled fermentation of gowé.     

Microbiological study of lactic acid fermentation of Caper berries by molecular and culture-dependent methods

Fermentation of capers (the fruits of Capparis sp.) was studied by molecular and culture-independent methods. A lactic acid fermentation occurred following immersion of caper berries in water, resulting in fast acidification and development of the organoleptic properties typical of this fermented food. A collection of 133 isolates obtained at different times of fermentation was reduced to 75 after randomly amplified polymorphic DNA (RAPD)-PCR analysis. Isolates were identified by PCR or 16S rRNA gene sequencing as Lactobacillus plantarum (37 isolates), Lactobacillus paraplantarum (1 isolate), Lactobacillus pentosus (5 isolates), Lactobacillus brevis (9 isolates), Lactobacillus fermentum (6 isolates), Pediococcus pentosaceus (14 isolates), Pediococcus acidilactici (1 isolate), and Enterococcus faecium (2 isolates). Cluster analysis of RAPD-PCR patterns revealed a high degree of diversity among lactobacilli (with four major groups and five subgroups), while pediococci clustered in two closely related groups. A culture-independent analysis of fermentation samples by temporal temperature gradient electrophoresis (TTGE) also indicated that L. plantarum is the predominant species in this fermentation, in agreement with culture-dependent results. The distribution of L. brevis and L. fermentum in samples was also determined by TTGE, but identification of Pediococcus at the species level was not possible. TTGE also allowed a more precise estimation of the distribution of E. faecium, and the detection of Enterococcus casseliflavus (which was not revealed by the culture-dependent analysis). Results from this study indicate that complementary data from molecular and culture-dependent analysis provide a more accurate determination of the microbial community dynamics during caper fermentation.     

Presence of erythromycin and tetracycline resistance genes in lactic acid bacteria from fermented foods of Indian origin

Lactic acid bacteria (LAB) resistant to erythromycin were isolated from different food samples on selective media. The isolates were identified as Enterococcus durans, Enterococcus faecium, Enterococcus lactis, Enterococcus casseliflavus, Lactobacillus salivarius, Lactobacillus reuteri, Lactobacillus plantarum, Lactobacillus fermentum, Pediococcus pentosaceus and Leuconostoc mesenteroides. Of the total 60 isolates, 88 % harbored the ermB gene. The efflux gene msrA was identified in E. faecium, E. durans, E. lactis, E. casseliflavus, P. pentosaceus and L. fermentum. Further analysis of the msrA gene by sequencing suggested its homology to msrC. Resistance to tetracycline due to the genes tetM, tetW, tetO, tetK and tetL, alone or in combination, were identified in Lactobacillus species. The tetracycline efflux genes tetK and tetL occurred in P. pentosaceus and Enterococcus species. Since it appeared that LAB had acquired these genes, fermented foods may be a source of antibiotic resistance.     

Lactic acid bacteria producing B-group vitamins: a great potential for functional cereals products

Wheat contains various essential nutrients including the B group of vitamins. However, B group vitamins, normally present in cereals-derived products, are easily removed or destroyed during milling, food processing or cooking. Lactic acid bacteria (LAB) are widely used as starter cultures for the fermentation of a large variety of foods and can improve the safety, shelf life, nutritional value, flavor and overall quality of the fermented products. In this regard, the identification and application of strains delivering health-promoting compounds is a fascinating field. Besides their key role in food fermentations, several LAB found in the gastrointestinal tract of humans and animals are commercially used as probiotics and possess generally recognized as safe status. LAB are usually auxotrophic for several vitamins although certain strains of LAB have the capability to synthesize water-soluble vitamins such as those included in the B group. In recent years, a number of biotechnological processes have been explored to perform a more economical and sustainable vitamin production than that obtained via chemical synthesis. This review article will briefly report the current knowledge on lactic acid bacteria synthesis of vitamins B2, B11 and B12 and the potential strategies to increase B-group vitamin content in cereals-based products, where vitamins-producing LAB have been leading to the elaboration of novel fermented functional foods. In addition, the use of genetic strategies to increase vitamin production or to create novel vitamin-producing strains will be also discussed.     

Metabolism of prebiotic products containing beta(2-1) fructan mixtures by two Lactobacillus strains

The capacity of two probiotic strains, isolated from human breast milk, to use several beta(2-1) fructan mixtures as carbon and energy source in in vitro cultures has been tested. Results showed that both strains, Lactobacillus gasseri CECT5714 and Lactobacillus fermentum CECT5716, reached higher growth levels on culture media containing fructooligosaccharide mixtures produced by enzymatic synthesis, compared to those obtained by inulin hydrolysis. Furthermore, the shortest beta(2-1) fructan, kestose, was the only prebiotic compound in the mixtures significantly metabolized in all growth media tested. Analysis of short-chain fatty acid production showed no correlation between the fatty acid profile produced and the carbon source used in each experiment. These data could serve to select appropriate beta(2-1) fructans to be used as prebiotics for L. gasseri CECT5714 and L. fermentum CECT5716 and to design suitable symbiotic food products containing the mentioned lactobacilli.     

Bioconversion of isoflavone glycosides to aglycones,mineral bioavailability and vitamin B complex in fermented soymilk by probiotic bacteria and yeast

Aim: To study the role of β‐glucosidase producing probiotic bacteria and yeast in the biotransformation of isoflavone glycosides to aglycones, mineral bioavailability and vitamin B complex in fermented soymilk. Methods and Results: Five isolates of probiotic lactic acid bacteria (LAB), Lactobacillus acidophilus B4496, Lactobacillus bulgaricus CFR2028, Lactobacillus casei B1922, Lactobacillus plantarum B4495 and Lactobacillus fermentum B4655 with yeast Saccharomyces boulardii were used to ferment soymilk to obtain the bioactive isoflavones, genistein and daidzein. High‐performance liquid chromatography was used to analyse the concentration of isoflavones. Bioactive aglycones genistein and daidzein after 24 and 48 h of fermentation ranged from 97·49 to 98·49% and 62·71 to 92·31% respectively with different combinations of LAB with yeast. Increase in bioavailability of minerals and vitamin B complex were also observed in fermented soymilk. Conclusions: LAB in combination with yeast S. boulardii has great potential for the enrichment of bioactive isoflavones, enhancing the viability of LAB strains, decreasing the antinutrient phytic acid and increasing the mineral bioavailability in soymilk fermentation. Significance and Impact of the Study: Fermentation of soymilk with probiotic organisms improves the bioavailability of isoflavones, assists in digestion of protein, provides more soluble calcium, enhances intestinal health and supports immune system. Increased isoflavone aglycone content in fermented soymilk improves the biological functionality of soymilk.     

Characterization of mannitol producing strains of Leuconostoc species

Mannitol is a naturally occurring low calorie sweetener, widely used in the food, pharmaceutical, medicine and chemical industries. In this study mannitol producing strains of Leuconostoc spp. (210) were isolated from a wide array of sources such as raw milk, fermented milks, fermented cereal foods, fruits, vegetables and sugar factory syrup. During initial screening, half of the population of these isolates (105) exhibited ability to produce mannitol to a variable extent. Only 11.4% isolate produced mannitol yield of above 80% (when fructose used @ 50 g/l). Cultural and environmental factors affecting growth and mannitol production were studied for four high mannitol producing isolates. High mannitol production was favored by high temperature and high pH. Isolates had high osmotic tolerance as these could use fructose concentration as high as 100 g/l in batch culture. Sequencing of 16S rRNA genes of the strains revealed that Ln27, Ln104 and Ln206 were Leuconostoc mesenteroides and Ln92 was Leuconostoc fallax.     

Functional and safety characterization of autochthonous Lactobacillus paracasei FS103 isolated from sheep cheese and its survival in sheep and cow fermented milks during cold storage

The main objective of this study was to evaluate some probiotic characteristics of Lactobacillus spp. isolated from traditional sheep cheese, and to investigate the fermentative ability and viability in sheep and cow milks of a selected potential probiotic Lactobacillus (L.) strain, i.e., L. paracasei FS103. A total of 54 autochthonous Lactobacillus isolates were characterized for (i) acidity and bile salt resistance, (ii) tolerance to gastric and intestinal juice models, and (iii) antagonistic activity against pathogens and antibiotic resistance. Potential probiotic Lactobacillus has been used in sheep and cow milks for the manufacturing of experimental fermented milks. In these latter, pH value, microbial count, and sensory analysis were carried out. Lactobacillus FS103 classified as L. paracasei subsp. paracasei had a good survival in gastric and intestinal juice models, inhibited the growth of undesirable bacteria, and was susceptible to chloramphenicol, clindamycin, penicillin, amoxicillin, erythromycin, tetracycline, and ampicillin. Moreover, when used to produce experimental sheep and cow fermented milks, L. paracasei FS103 was able to acidify both milk types leading to a continuous pH decrease during all fermentation time (24 h). FS103 population remains viable at a level > 108 CFU mL−1 after 21 days of cold (4 °C) storage. The results of sensory analysis showed that scores related to consistency, taste, and astringent were significantly higher in sheep fermented milk while animal-like was less acceptable compared to cow fermented milk. Lactobacillus paracasei FS103 isolated from sheep cheese exhibited potential probiotic properties and suitable features for sheep and cow fermented milks maintaining high vitality during cold storage.     

应用rep-PCR分型技术筛选潜在治疗性乳杆菌

分离鉴定阴道弯曲乳酸杆菌并对其进行基因分型分析和产H2O2能力测定,初步筛选具有潜在防治女性生殖道感染的弯曲乳酸杆菌菌株。将健康妇女阴道分泌物接种到de Man,Rogosa and Sharpe (MRS) 培养基,分离培养乳酸杆菌。通过16S rRNA序列进行乳酸杆菌分类鉴定,重复序列片段PCR扩增方法进行弯曲乳酸杆菌的基因分型,并进一步采用pH直接测酸法和辣根过氧化物酶催化四甲基联苯胺与过氧化氢反应显色法检测了10株弯曲乳酸杆菌产酸和产H2O2能力。经过序列比对鉴定,共得到65株乳酸杆菌。其中,弯曲乳杆菌Lactobacillus crispatus 19株,詹氏乳杆菌Lactobacillus jensenii 17株,发酵乳杆菌Lactobacillus fermentum 12株;rep-PCR分型发现不同种类的乳酸杆菌和同一种弯曲乳酸杆菌均表现为不同的带型指纹图;10株弯曲乳酸杆菌均产酸,其中T22-3和T29-5两株弯曲乳酸杆菌产H2O2量最高。结果表明个体阴道内乳酸杆菌分布具有差异,弯曲乳酸杆菌具有种内多样性,产H2O2丰富的T22-3和T29-5两株弯曲乳酸杆菌有可能作为防治女性生殖道感染的有益菌株。     

Interesting starter culture strains for controlled cocoa bean fermentation revealed by simulated cocoa pulp fermentations of cocoa-specific lactic acid bacteria

Among various lactic acid bacterial strains tested, cocoa-specific strains of Lactobacillus fermentum were best adapted to the cocoa pulp ecosystem. They fermented glucose to lactic acid and acetic acid, reduced fructose to mannitol, and converted citric acid into lactic acid and 2,3-butanediol.     

Optimization of cholesterol removal, growth and fermentation patterns of Lactobacillus acidophilus ATCC 4962 in the presence of mannitol, fructo-oligosaccharide and inulin: a response surface methodology approach

AIMS: To optimize cholesterol removal by Lactobacillus acidophilus ATCC 4962 in the presence of prebiotics, and study the growth and fermentation patterns of the prebiotics. METHODS AND RESULTS: Lactobacillus acidophilus ATCC 4962 was screened in the presence of six prebiotics, namely sorbitol, mannitol, maltodextrin, hi-amylose maize, fructo-oligosaccharide (FOS) and inulin in order to determine the best combination for highest level of cholesterol removal. The first-order model showed that the combination of inoculum size, mannitol, FOS and inulin was best for removal of cholesterol. The second-order polynomial regression model estimated the optimum condition of the factors for cholesterol removal by L. acidophilus ATCC 4962 to be 2.64% w/v inoculum size, 4.13% w/v mannitol, 3.29% w/v FOS and 5.81% w/v inulin. Analyses of growth, mean doubling time and short-chain fatty acid (SCFA) production using quadratic models indicated that cholesterol removal and the production of SCFA were growth associated. CONCLUSIONS: Optimum cholesterol removal was obtained from the fermentation of L. acidophilus ATCC 4962 in the presence of mannitol, FOS and inulin. Cholesterol removal and the production of SCFA appeared to be growth associated and highly influenced by the prebiotics. SIGNIFICANCE AND IMPACT OF THE STUDY: Response surface methodology proved reliable in developing the model, optimizing factors and analysing interaction effects. The results provide better understanding on the interactions between probiotic and prebiotics for the removal of cholesterol.