Comparison of Fructooligosaccharide Utilization by Lactobacillus and Bacteroides Species

The utilization of 1-kestose (GF₂) and nystose (GF₃), the main components of fructooligosaccharides (FOS), by Lactobacillus and Bacteroides species was examined. Of seven Lactobacillus and five Bacteroides strains that utilized FOS, L. salivarius, L. rhamnosus, L. casei, and L. gasseri utilized only GF₂, whereas L. acidophilus and all the Bacteroides strains utilized both GF₂ and GF₃. Only the strains able to utilize both GF₂ and GF₃ had β-fructosidase activity in the culture supernatants. The culture supernatants of the Lactobacillus strains had higher β-fructosidase activity for GF₂ than for GF₃, whereas those of the Bacteroides strains had higher activity for GF₃ than for GF₂. Furthermore, β-fructosidase activity of the culture supernatants of the Lactobacillus cells grown in the GF₃ medium was much higher than that of the cells grown in the GF₂ medium, whereas the activity of the culture supernatants of the Bacteroides cells grown in the GF₃ medium was almost the same as that of the cells grown in the GF₂ medium. These results indicate that Lactobacillus species metabolize FOS in a different way from that of Bacteroides species.     

Identification of Prebiotic Fructooligosaccharide Metabolism in Lactobacillus plantarum WCFS1 through Microarrays

Short-chain fructooligosaccharides (scFOS) and other prebiotics are used to selectively stimulate the growth and activity of lactobacilli and bifidobacteria in the colon. However, there is little information on the mechanisms whereby prebiotics exert their specific effects upon such microorganisms. To study the genomic basis of scFOS metabolism in Lactobacillus plantarum WCFS1, two-color microarrays were used to screen for differentially expressed genes when grown on scFOS compared to glucose (control). A significant up-regulation (8- to 60-fold) was observed with a set of only five genes located in a single locus and predicted to encode a sucrose phosphoenolpyruvate transport system (PTS), a β-fructofuranosidase, a fructokinase, an α-glucosidase, and a sucrose operon repressor. Several other genes were slightly overexpressed, including pyruvate dehydrogenase. For the latter, no detectable activity in L. plantarum under various growth conditions has been previously reported. A mannose-PTS likely to encode glucose uptake was 50-fold down-regulated as well as, to a lower extent, other PTSs. Chemical analysis of the different moieties of scFOS that were depleted in the growth medium revealed that the trisaccharide 1-kestose present in scFOS was preferentially utilized, in comparison with the tetrasaccharide nystose and the pentasaccharide fructofuranosylnystose. The main end products of scFOS fermentation were lactate and acetate. This is the first example in lactobacilli of the association of a sucrose PTS and a β-fructofuranosidase that could be used for scFOS degradation.     

Metabolism of fructooligosaccharides by Lactobacillus paracasei 1195

Fermentation of fructooligosaccharides (FOS) and other oligosaccharides has been suggested to be an important property for the selection of bacterial strains used as probiotics. However, little information is available on FOS transport and metabolism by lactic acid bacteria and other probiotic bacteria. The objectives of this research were to identify and characterize the FOS transport system of Lactobacillus paracasei 1195. Radiolabeled FOS was synthesized enzymatically from [(3)H]sucrose and purified by column and thin-layer chromatography, yielding three main products: glucose (G) alpha-1,2 linked to two, three, or four fructose (F) units (GF(2), GF(3), and GF(4), respectively). FOS hydrolysis activity was detected only in cell extracts prepared from FOS- or sucrose-grown cells and was absent in cell supernatants, indicating that transport must precede hydrolysis. FOS transport assays revealed that the uptake of GF(2) and GF(3) was rapid, whereas little GF(4) uptake occurred. Competition experiments showed that glucose, fructose, and sucrose reduced FOS uptake but that other mono-, di-, and trisaccharides were less inhibitory. When cells were treated with sodium fluoride, iodoacetic acid, or other metabolic inhibitors, FOS transport rates were reduced by up to 60%; however, ionophores that abolished the proton motive force only slightly decreased FOS transport. In contrast, uptake was inhibited by ortho-vanadate, an inhibitor of ATP-binding cassette transport systems. De-energized cells had low intracellular ATP concentrations and had a reduced capacity to accumulate FOS. These results suggest that FOS transport in L. paracasei 1195 is mediated by an ATP-dependent transport system having specificity for a narrow range of substrates.     

Metabolism of Fructooligosaccharides by Lactobacillus paracasei 1195

Fermentation of fructooligosaccharides (FOS) and other oligosaccharides has been suggested to be an important property for the selection of bacterial strains used as probiotics. However, little information is available on FOS transport and metabolism by lactic acid bacteria and other probiotic bacteria. The objectives of this research were to identify and characterize the FOS transport system of Lactobacillus paracasei 1195. Radiolabeled FOS was synthesized enzymatically from [³H]sucrose and purified by column and thin-layer chromatography, yielding three main products: glucose (G) α-1,2 linked to two, three, or four fructose (F) units (GF₂, GF₃, and GF₄, respectively). FOS hydrolysis activity was detected only in cell extracts prepared from FOS- or sucrose-grown cells and was absent in cell supernatants, indicating that transport must precede hydrolysis. FOS transport assays revealed that the uptake of GF₂ and GF₃ was rapid, whereas little GF₄ uptake occurred. Competition experiments showed that glucose, fructose, and sucrose reduced FOS uptake but that other mono-, di-, and trisaccharides were less inhibitory. When cells were treated with sodium fluoride, iodoacetic acid, or other metabolic inhibitors, FOS transport rates were reduced by up to 60%; however, ionophores that abolished the proton motive force only slightly decreased FOS transport. In contrast, uptake was inhibited by ortho-vanadate, an inhibitor of ATP-binding cassette transport systems. De-energized cells had low intracellular ATP concentrations and had a reduced capacity to accumulate FOS. These results suggest that FOS transport in L. paracasei 1195 is mediated by an ATP-dependent transport system having specificity for a narrow range of substrates.     

Differentiation of Lactobacillus casei, Lactobacillus paracasei and Lactobacillus rhamnosus by polymerase chain reaction

Lactobacillus casei, Lact. paracasei and Lact. rhamnosus form a closely related taxonomic group within the heterofermentative lactobacilli. These three species are difficult to differentiate using traditional fermentation profiles. We have developed polymerase chain reaction primers which are specific for each of these species based on differences in the V1 region of the 16S rRNA gene. Sixty-three Lactobacillus isolates from cheese were identified using these primers. The 12 Lact. rhamnosus and 51 Lact. paracasei identified in this way were also differentiated using a randomly amplified polymorphic DNA (RAPD) primer.     

副干酪乳杆菌的应用研究进展

副干酪乳杆菌(Lactobacillus paracasei)属于乳杆菌属中的干酪乳杆菌(Lactobacillus casei)群。本文简单介绍了副干酪乳杆菌的分布、分类学地位及其主要鉴定手段,综述了该菌种及其细菌素和质粒在L-乳酸的工业生产、食品发酵及防腐、医疗保健、废料的循环利用和科学研究等方面的应用。     

Safety evaluation of Lactobacillus paracasei subsp. paracasei LC-01, a probiotic bacterium

The safety of Lactobacillus paracasei subsp. paracasei LC-01 was evaluated for its use as a potential probiotic. In our in vitro study, the antibiotic resistance and the ability to produce biogenic amine were determined. The results showed that the strain was sensitive to all tested antibiotics and did not produce biogenic amine except for tyramine. The oral toxicity of this strain was evaluated in Balb/C mice. One hundred mice were divided into 10 groups. Four groups were administered 0, 10⁸, 10⁹, or 10¹⁰ CFU/mouse per day dissolved in saline solution respectively, for 28 days. Three groups were injected intraperitoneally with 10⁹ CFU/mouse dissolved in saline solution, and were killed 2, 5, and 10 days after injection. The last 3 groups were injected with the vehicle as controls respectively. The results showed that oral administration of the strain had no adverse effects on mouse body weight and that there was no treatment-associated bacterial translocation. Intraperitoneal administration caused a significant translocation to liver, spleen and kidney. However, this translocation did not cause illness or death throughout the experiment. The results suggest that L. paracasei subsp. paracasei LC-01 is likely to be safe for human consumption.     

Selection of Escherichia coli-inhibiting strains of Lactobacillus paracasei subsp. paracasei

The aim of this study was to select Escherichia coli-inhibiting strains among lactic acid bacteria. On the basis of phenotypical and technological characteristics, 20 strains of lactic acid bacteria were screened from a total of 225 isolates, obtained from nine samples of artisanal Caprino d'Aspromonte cheese, made from raw goats' milk. The antagonistic activity of these 20 strains was detected in plates against three different strains of E. coli. Two strains of Lactobacillus paracasei subsp. paracasei showed a marked anti-E. coli activity against all three strains tested; the other lactic acid bacteria did not exhibit inhibiting activity. The E. coli inhibition can be ascribed to production of bacteriocin-like compounds. The use of L. paracasei subsp. paracasei strains to increase the safety of the cheeses made from raw milk is recommended because these cultures strongly inhibit E. coli, without foreseeable adverse sensory changes. Received 27 December 2001/ Accepted in revised form 28 June 2002     

Comparative studies of the degradation of grass fructan and inulin by strains of Lactobacillus paracasei subsp. paracasei and Lactobacillus plantarum

Four strains of Lactobacillus paracasei subsp. paracasei and Lact. plantarum are investigated within 16 d in order to determine the formation of metabolites during the degradation of grass fructan and inulin as well as the subsequent fermentation to lactic acid. The decrease of the total content of fructans throughout the entire time of investigation shows differences specific for strains as for either fructan substrate. The strain Lact. plantarum V 54/6 completely degrades the grass fructan and inulin within no longer than 13 d. The utilization of fructan by the other strains is temporally delayed, and in a smaller degree of degradation, especially remarkable for inulin cleavage. The structural modifications of decomposed fructans are characterized by a noticeable shift of the mean DP from approximately 80 to the oligomeric range analysed by anion exchange chromatography. Additionally, a newly formed series of peaks of oligomeric saccharides was detected during the degradation of grass fructan and inulin. Part of the fructose that is derived from cleavage of fructans is fermented immediately by the LAB strains into differently high amounts of lactic acid. The abundance of formed fructose is enriched in the medium to a varying extent, depending on the strain as well as the substrate used. From these results a number of fructan degradative enzymes in lactobacilli have been concluded to possibly vary their modes of regulation: strain specific exo- and endohydrolases with different activities against β-2,1 and β-2,6 linked fructan.     

Antimicrobial and antiadhesive properties of a biosurfactant isolated from Lactobacillus paracasei ssp. paracasei A20

Aims: The aim of this study was to determine the antimicrobial and antiadhesive properties of a biosurfactant isolated from Lactobacillus paracasei ssp. paracasei A20 against several micro‐organisms, including Gram‐positive and Gram‐negative bacteria, yeasts and filamentous fungi. Methods and Results: Antimicrobial and antiadhesive activities were determined using the microdilution method in 96‐well culture plates. The biosurfactant showed antimicrobial activity against all the micro‐organisms assayed, and for twelve of the eighteen micro‐organisms (including the pathogenic Candida albicans, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus agalactiae), the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were achieved for biosurfactant concentrations between 25 and 50 mg ml^?1. Furthermore, the biosurfactant showed antiadhesive activity against most of the micro‐organisms evaluated. Conclusions: As far as we know, this is the first compilation of data on antimicrobial and antiadhesive activities of biosurfactants obtained from lactobacilli against such a broad group of micro‐organisms. Although the antiadhesive activity of biosurfactants isolated from lactic acid bacteria has been widely reported, their antimicrobial activity is quite unusual and has been described only in a few strains. Significance and Impact of the Study: The results obtained in this study regarding the antimicrobial and antiadhesive properties of this biosurfactant opens future prospects for its use against micro‐organisms responsible for diseases and infections in the urinary, vaginal and gastrointestinal tracts, as well as in the skin, making it a suitable alternative to conventional antibiotics.     

Distinct immunomodulatory properties of Lactobacillus paracasei strains

Aims: This study was performed to ascertain the immunomodulatory effect of Lactobacillus paracasei strains. These strains were also genetically characterized. Methods and Results: The strains were genetically differentiated by using the fluorescent‐amplified fragment length polymorphism technique, which led to the identification of several molecular markers unique to each strain. To determine the immunomodulatory properties, we evaluated the effect of strains on dendritic cell maturation, dextran uptake, ability to induce proliferation of allogenic T cells and cytokine secretion. The results indicated that all the strains stimulated phenotypic maturation of dendritic cells (DCs), but they acted differently on DCs in relation to the other tested properties; notably, a different effect on cytokine secretion was detected. Conclusions: The results of this study revealed different immunomodulatory properties of strains of the species Lact. paracasei. Strain IMPC 4.1 showed an interesting anti‐inflammatory ability. Probiotic strains IMPC 2.1 and LMG P‐17806 were characterized by a similar and intermediate ability to induce cytokine secretion in contrast to the very low ability of strain LMG 23554. Significance and Impact of Study: Our results confirm that each single strain of a bacterial species appears to influence the immune system in a peculiar manner. The evaluation of the different types and/or levels of cytokines whose secretion is induced by each strain could be relevant to define its pro‐ or anti‐inflammatory properties and its more appropriate clinical use.     

Identification of a Putative P-Transporter Operon in the Genome of a Burkholderia Strain Living inside the Arbuscular Mycorrhizal Fungus Gigaspora margarita

This article reports the identification of a putative P-transporter operon in the genome of a Burkholderia sp. living in the cytoplasm of the arbuscular mycorrhizal fungus Gigaspora margarita. Its presence suggests that Burkholderia sp. has the potential for P uptake from this environment. This finding raises new questions concerning the importance of intracellular bacteria for mycorrhizal symbiosis.