Phage Receptor Material in Lactobacillus casei Cell Wall

A trichloroacetic acid (TCA)-soluble fraction, extracted using cold TCA, was derived from the cell wall of Lactobacillus casei strain S-1. It not only inhibited the adsorption of phage J-l but also desorbed these phages, in their active form, which had previously been adsorbed onto the cell walls. l-Rhamnose, one of the components of this TCA-soluble fraction, had an identical activity to this TCA-soluble fraction, on phage adsorption. This suggested that l-rhamnose is a part of phage receptor material in the cell wall of L. casei strain S-l; and the binding of the phage to the cell wall is reversible, even at 37 C.     

Antiviral activity of Lactobacillus brevis towards herpes simplex virus type 2: role of cell wall associated components

The aim of this research was to study the mechanisms of Lactobacillus brevis antiviral activity towards HSV-2 and to identify the bacterial components responsible for the inhibiting effect. Bacterial extract and cell walls were prepared by lysozyme digestion of L. brevis cells untreated or treated with LiCl to remove S-layer proteins. Bacterial extract and cell wall fragments showed a dose dependent inhibitory effect on HSV-2 multiplication. In order to characterize the inhibitory activity of L. brevis, the bacterial extract was subjected to different physical and chemical treatments. The inhibitory activity was resistant to high temperature and proteases digestion and appeared to be associated with compounds with a molecular weight higher than 10 kDa. DNA, RNA and lipids isolated from bacterial cells were devoid of inhibitory effect. The antiviral activity of both bacterial extract and cell wall fragments obtained from L. brevis cells after the S-layer removal was significantly reduced compared to untreated cells suggesting that the inhibitory activity is likely due to a heat-resistant non-protein cell surface bacterial component.     

Characterization of Non-Starter Lactic Acid Bacteria from Italian Ewe Cheeses Based on Phenotypic, Genotypic, and Cell Wall Protein Analyses

Non-starter lactic acid bacteria (NSLAB) were isolated from 12 Italian ewe cheeses representing six different types of cheese, which in several cases were produced by different manufacturers. A total of 400 presumptive Lactobacillus isolates were obtained, and 123 isolates and 10 type strains were subjected to phenotypic, genetic, and cell wall protein characterization analyses. Phenotypically, the cheese isolates included 32% Lactobacillus plantarum isolates, 15% L. brevis isolates, 12% L. paracasei subsp. paracasei isolates, 9% L. curvatus isolates, 6% L. fermentum isolates, 6% L. casei subsp. casei isolates, 5% L. pentosus isolates, 3% L. casei subsp. pseudoplantarum isolates, and 1% L. rhamnosus isolates. Eleven percent of the isolates were not phenotypically identified. Although a randomly amplified polymorphic DNA (RAPD) analysis based on three primers and clustering by the unweighted pair group method with arithmetic average (UPGMA) was useful for partially differentiating the 10 type strains, it did not provide a species-specific DNA band or a combination of bands which permitted complete separation of all the species considered. In contrast, sodium dodecyl sulfate-polyacrylamide gel electrophoresis cell wall protein profiles clustered by UPGMA were species specific and resolved the NSLAB. The only exceptions were isolates phenotypically identified as L. plantarum and L. pentosus or as L. casei subsp. casei and L. paracasei subsp. paracasei, which were grouped together. Based on protein profiles, Italian ewe cheeses frequently contained four different species and 3 to 16 strains. In general, the cheeses produced from raw ewe milk contained a larger number of more diverse strains than the cheeses produced from pasteurized milk. The same cheese produced in different factories contained different species, as well as strains that belonged to the same species but grouped in different RAPD clusters.     

Suppressive Effect on Activation of Macrophages by Lactobacillus casei Strain Shirota Genes Determining the Synthesis of Cell Wall-Associated Polysaccharides

Although many Lactobacillus strains used as probiotics are believed to modulate host immune responses, the molecular natures of the components of such probiotic microorganisms directly involved in immune modulation process are largely unknown. We aimed to assess the function of polysaccharide moiety of the cell wall of Lactobacillus casei strain Shirota as a possible immune modulator which regulates cytokine production by macrophages. A gene survey of the genome sequence of L. casei Shirota hunted down a unique cluster of 10 genes, most of whose predicted amino acid sequences had similarities to various extents to known proteins involved in biosynthesis of extracellular or capsular polysaccharides from other lactic acid bacteria. Gene knockout mutants of eight genes from this cluster resulted in the loss of reactivity to L. casei Shirota-specific monoclonal antibody and extreme reduction of high-molecular-mass polysaccharides in the cell wall fraction, indicating that at least these genes are involved in biosynthesis of high-molecular-mass cell wall polysaccharides. By adding heat-killed mutant cells to mouse macrophage cell lines or to mouse spleen cells, the production of tumor necrosis factor alpha, interleukin-12 (IL-12), IL-10, and IL-6 was more stimulated than by wild-type cells. In addition, these mutants additively enhanced lipopolysaccharide-induced IL-6 production by RAW 264.7 mouse macrophage-like cells, while wild-type cells significantly suppressed the IL-6 production of RAW 264.7. Collectively, these results indicate that this cluster of genes of L. casei Shirota, which have been named cps1A, cps1B, cps1C, cps1D, cps1E, cps1F, cps1G, and cps1J, determine the synthesis of the high-molecular-mass polysaccharide moiety of the L. casei Shirota cell wall and that this polysaccharide moiety is the relevant immune modulator which may function to reduce excessive immune reactions during the activation of macrophages by L. casei Shirota.     

Grouping Antigens of Four Lactobacillus Species and Their Characteristics

Antigenic analyses of Lactobacillus bulgaricus, Lactobacillus lactis, Lactobacillus brevis and Lactobacillus buchneri were carried out by double immunodiffusion in agar. Antigens were extracted from whole cells and cell wall preparations with cold trichloroacetic acid. Most strains of the four species possessed antigen 9 in their cell walls. Another antigen, antigen 10, was found in the cell walls of all the strains of L. brevis and L. buchneri, and in some strains of L. lactis, but not in L. bulgaricus. Fractionation of the antigens was attempted using the cell wall extracts of L. lactis L-10 with only antigen 9 and of L. brevis X-1 with both antigens 9 and 10. The partially purified fractions of antigen 9 and of the complex of antigens 9 and 10 were obtained by zone electrophoresis. However, antigen 10 from the complex could not be separated by the same method or gel filtration on Sephadex G-100 since the two antigens 9 and 10 of the complex always behaved together. The fraction of antigen 9 consisted almost entirely of glycerol and glucose as sugar components, the molar ratio being 2:1. The complex of antigens 9 and 10 also consisted of the same sugars, and the molar ratio of glycerol: glucose was 4:1. Inhibition tests indicated that the immunodominant component of antigen 9 was α-methylglucoside (glucose), and most probably the determinant is a glucosylated glycerol teichoic acid. It was considered that the determinant of antigen 10 is a glycerol teichoic acid although glucosamine and galactosamine inhibited effectively the reaction between antigen 10 and its antibody.     

The effect of caffeine,different fixation regimes and low temperature on microtubules in the cells of higher plants

Caffeine, (1:3:7-tri-methyl-xanthine), either as a prefixation treatment or included with glutaralde-hyde as the primary fixative, destroys or disorganises the microtubules associated with the formation of secondary walls in fibres from the flowering stem of the grass Lolium temulentum L. There is no observable effect of caffeine treatment on the microtubules associated with primary wall formation in collenchyma and young fibres from L. temulentum or in root cap cells of Zea mays L. and Phaseolus vulgaris L. The microtubules associated with primary wall formation are destroyed by cold treatment but not those associated with secondary wall formation. Tannic acid included in the fixative shows the microtubules associated with secondary wall formation in fibres of L. temulentum to be composed of 13 subunits. Treatment with lanthanum hydroxide does not stain the core or the halo of the microtubules.Abbreviation PIPES Piperazine N-N- bis 2 ethanol sulphonic acid The Grassland Research Institute is financed through the Agricultural Research Council     

Antigenic Analyses of Lactobacillus fermenti

Antigenic analyses of Lactobacillus fermenti were carried out by double immunodiffusion in agar using extracts prepared with cold trichloroacetic acid (TCA) or hot dilute hydrochloric acid (HCl). A common antigen of L. fermenti, designated as antigen f by the author, was extracted from whole cells with dilute HCl, but not with TCA. The antigen f was also observed in Lactobacillus casei. In addition, all strains isolated from human saliva contained antigen 6 in their cell walls, while the antigen was not observed in most of the isolates from human feces. Therefore, L. fermenti could be divided into two subgroups based upon the existence of antigen 6. Antigen 7 which was demonstrated in some strains of L. fermenti was shared by other species of lactobacilli belonging to the serological groups D and E. The common antigen 3 found in lactobacilli was extracted from all strains of L. fermenti. Sugar components of cell walls were mainly galactose, glucose and glucosamine (including N-acetylglueosamine), but a small amount of rhamnose was present in the cell wall of only one strain. Inhibition tests with various sugars showed that the serologically active sugars were galactose for antigen f and glucose for antigen 6.     

短乳杆菌与植物乳杆菌的发酵特性

【背景】目前对于酸菜发酵的研究主要关注点是植物乳杆菌(Lactobacillus plantarum),有关短乳杆菌(Lactobacillus brevis)在酸菜方面的研究报道很少。【目的】为了挖掘短乳杆菌的发酵性能并开发酸菜发酵剂,将2株短乳杆菌分别与1株植物乳杆菌进行组合并发酵酸菜,分析短乳杆菌对酸菜发酵品质的影响。【方法】分别测定短乳杆菌与植物乳杆菌的单菌株生长产酸性能、耐酸性及亚硝酸盐降解力,并将两菌种组合后发酵酸菜,分析1-7d内酸度、乳酸菌活菌数、亚硝酸盐含量及酸菜质构特性的变化趋势。【结果】相较于短乳杆菌Lb-9-2,短乳杆菌Lb-5-3的生长和产酸速率较慢、酸耐受力较弱,但其亚硝酸盐降解力较强。两株短乳杆菌分别与植物乳杆菌Lp-9-1组合后产酸力显著增强,并在3 d时达到最低pH值(约3.10);植物乳杆菌Lp-9-1的添加使酸菜中总体乳酸菌生长延迟,在5 d时达到最高活菌数;组合菌种的样品中亚硝酸盐含量在1-7 d内变化较为平缓,前5天内两个组合之间差异不显著;接种乳酸菌会降低酸菜硬度和弹性,发酵3d时Lb-5-3/Lp-9-1组合的硬度最大,感官评价得分最高。【...     

The S-Layer Proteins of Two Bacillus stearothermophilus Wild-Type Strains Are Bound via Their N-Terminal Region to a Secondary Cell Wall Polymer of Identical Chemical Composition

Two Bacillus stearothermophilus wild-type strains were investigated regarding a common recognition and binding mechanism between the S-layer protein and the underlying cell envelope layer. The S-layer protein from B. stearothermophilus PV72/p6 has a molecular weight of 130,000 and assembles into a hexagonally ordered lattice. The S-layer from B. stearothermophilus ATCC 12980 shows oblique lattice symmetry and is composed of subunits with a molecular weight of 122,000. Immunoblotting, peptide mapping, N-terminal sequencing of the whole S-layer protein from B. stearothermophilus ATCC 12980 and of proteolytic cleavage fragments, and comparison with the S-layer protein from B. stearothermophilus PV72/p6 revealed that the two S-layer proteins have identical N-terminal regions but no other extended structurally homologous domains. In contrast to the heterogeneity observed for the S-layer proteins, the secondary cell wall polymer isolated from peptidoglycan-containing sacculi of the different strains showed identical chemical compositions and comparable molecular weights. The S-layer proteins could bind and recrystallize into the appropriate lattice type on native peptidoglycan-containing sacculi from both organisms but not on those extracted with hydrofluoric acid, leading to peptidoglycan of the A1γ chemotype. Affinity studies showed that only proteolytic cleavage fragments possessing the complete N terminus of the mature S-layer proteins recognized native peptidoglycan-containing sacculi as binding sites or could associate with the isolated secondary cell wall polymer, while proteolytic cleavage fragments missing the N-terminal region remained unbound. From the results obtained in this study, it can be concluded that S-layer proteins from B. stearothermophilus wild-type strains possess an identical N-terminal region which is responsible for anchoring the S-layer subunits to a secondary cell wall polymer of identical chemical composition.     

Xylan-mediated aggregation of Lactobacillus brevis and its relationship with the surface properties and mucin-mediated aggregation of the bacteria

Some Lactobacillus brevis strains were found to aggregate upon the addition of xylan after screening for lactic acid bacteria that interact with plant materials. The S-layer proteins of cell surface varied among the strains. The strains that displayed xylan-mediated aggregation retained its ability even after the removal of S-layer proteins. L. brevis had negative zeta potentials. A correlation between the strength of aggregation and zeta potential was not observed. However, partial removal of S-layer proteins resulted in decreases in the electric potential and aggregation ability of some strains. Therefore, xylan-mediated aggregation of L. brevis was considered to be caused by an electrostatic effect between the cells and xylan. L. brevis also aggregated in the presence of mucin, and the strengths of aggregation among the strains were similar to that induced by xylan. Thus, xylan- and mucin-mediated L. brevis aggregation was supposed to be caused by a similar mechanism.     

Cell wall assembly in vitro from Chlamydomonas reinhardi

Summary The conditions for in vitro dissociation and reassembly of the cell wall of Chlamydomonas reinhardi have been investigated. The cell wall dissociates in aqueous 8 M lithium chloride to two homogeneous components (6.8 S₂₀w and 9.3 S₂₀w)and dialysis of the cell wall subunits against water causes reassembly of a product having the same overall morphology and chemically similar to the original cell walls. Cell wall subunits in 8 M lithium chloride alone do not reassemble on dialysis against water to form cell walls but a nucleation centre has to be provided.     

Chemical Studies on the Cell Walls of Leptospira biflexa Strain Urawa and Treponema pallidum Strain Reiter

The preparation and chemical poperties of the cell walls of Leptospira biflexa Urawa and Treponema pallidum Reiter are described. Both cell walls are composed mainly of polysaccharides and peptidoglycans. The data of chemical analysis indicate that the cell wall of L. biflexa Urawa contains rhamnose, arabinose, xylose, mannose, galactose, glucose and unidentified sugars as neutral sugars, and alanine, glutamic acid, α,ε-diaminopimelic acid, glucosamine and muramic acid as major amino acids and amino sugars. As major chemical constituents of the cell wall of T. pallidum Reiter, rhamnose, arabinose, xylose, mannose, galactose, glucose, alanine, glutamic acid, ornithine, glycine, glucosamine and muramic acid have been detected. The chemical properties of protein and polysaccharide fractions prepared from the cells of T. pallidum Reiter were also partially examined.     

Effect of lactic acid on diacetyl and acetoin production byLactobacillus casei subsp.rhamnosus ATCC 7469

Lactic acid or its acidity apparently play an important role in the regulation of the biosynthesis of flavor compounds inLactobacillus casei subsp.rhamnosus ATCC 7469. In pyruvate-containing media,L. casei produces lactic acid, acetoin, and diacetyl. A specific pH-dependent system is necessary for both the use of pyruvate and the induction of acetoin and diacetyl production. In cell extracts ofL. casei, lactic acid inhibits the enzymatic activity of acetolactate decarboxylase (ALD) and acetolactate synthetase (ALS); this effect does not occur in whole cells under standard physiological conditions. Lactic acid prevents the use of pyruvate, and the induction of acetoin and diacetyl production. When pyruvate-containing media are used, the pH must be kept close to 6.0 in order to obtain the best production of acetoin and diacetyl.     

Chemical Composition of the Cell Walls of Clostridium botulinum Type A

Cell walls were isolated by sonic disruption of log-phase cells of Clostridium botulinum type A strain 190L and purified by treatment with sodium dodecyl sulfate (SDS) followed by digestion with proteases. Electron microscopy revealed that the cell walls thus obtained were free of both cytoplasmic membrane and cytoplasmic fragments. The purified cell wall contained 8.7% total nitrogen, 15.0% total hexosamines, 22.4% reducing groups, 8.3% carbohydrate, and 3.1% glucose. The content of total phosphorus was very low (0.02%), and therefore it was expected that teichoic acid might be absent in the cell wall. The wall peptidoglycan contained glutamic acid, alanine, diaminopimelic acid, glucosamine and muramic acid in the molar ratios of 1.00:1.85:0:85:1.06:0.67. A low amount of galactosamine was also present, but no other amino acids were found in significant quantities. The SDS-treated cell walls were not attacked by lysozyme, but after extraction with hot formamide they were completely dissolved by the enzyme and released reducing groups. The lysozyme digest was separated into two constituents, the saccharide moiety and the peptide moiety on Sephadex G-50.     

Stimulatory Effect of Inhibitors of Cell Wall Synthesis on Protein Production by Bacillus brevis

Mutants of Bacillus brevis No. 47 that grew in synthetic media containing a high concentration of ammonium sulfate were stable and had high protein production. Among various antibiotics tested, inhibitors of cell wall synthesis, such as bacitracin or β-lactam antibiotics, were effective in greatly increasing the accumulation of exoproteins.

When 60 µg/ml of bacitracin was added to the culture at the early logarithmic growth phase, about 9 mg/ml of proteins was produced. Such a protein yield was estimated to be nearly maximum from a given amount of glucose. Alterations in cell wall components were found in cells grown in the presence of bacitracin. Possible relationships between cell wall structure and protein production were discussed.     

Strain identification of probiotic Lactobacillus casei-related isolates with randomly amplified polymorphic DNA and pulsed-field gel electrophoresis methods

Typing of reference strains and isolates identified as Lactobacillus casei, Lactobacillus paracasei or Lactobacillus rhamnosus was carried out using randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) analyses. Strains of L. paracasei were mainly grouped in the same cluster as those of L. casei. The RAPD fingerprints of strains ATCC 393 and ATCC 15820 differ from those of the L. rhamnosus and L. paracasei/casei strains further supporting classification of these strains as a separate group. The RAPD profiling could be used for classification and discrimination of isolates belonging to the L. casei group.     

Aggregation of Lactobacillus brevis associated with decrease in pH by glucose fermentation

ABSTRACT

Some Lactobacillus brevis strains were found to aggregate upon the addition of glucose, which resulted in glucose fermentation and pH decrease. Surface layer proteins (Slp) that represented the outermost layer of the bacteria decreased under these low pH conditions, probably because of the partial detachment of Slp from the cell surface triggered by the acidic environment. Similar observations of decreased Slp and aggregation were observed under the culture conditions, confirming that L. brevis aggregation was due to the partial Slp detachment under the acidic conditions of glucose fermentation. Such Slp detachment might affect the electrostatic nature of L. brevis cells by initiating the formation of irregular charge across the L. brevis cell surface, thereby leading to aggregation. These observations would be useful for elucidating the aggregation mechanism of lactic acid bacteria, which was considered to be involved in the probiotic effect of the bacteria.     

Conjugated linoleic acid producing potential of lactobacilli isolated from the rumen of cattle

Lactobacilli isolated from the rumen of cattle were subjected to morphological and biochemical characterizations followed by PCR-based identification. Among isolates, Lactobacillus brevis was found to be the most prevalent species in the rumen. For in vitro conjugated linoleic acid (CLA) production, the two isolates of L. brevis and one each of Lactobacillus viridescens and Lactobacillus lactis were selected. The sunflower oil (i.e., 0.25, 0.5 and 1.0%; a rich source of linoleic acid) was added to skim milk as a substrate for CLA production by isolates at 37 °C/12 h. L. brevis 02 was found to be the most potential CLA producer (10.53 mg CLA/g fat) at 0.25% concentration of sunflower oil followed by L. brevis 01 (8.27 mg CLA/g fat). However, at higher level of sunflower oil (i.e., 1.0%), L. lactis was the highest CLA producer (9.22 mg/g fat) when compared to L. brevis and L. viridescens. The results indicated that L. brevis and/or CLA production was inhibited with increasing concentration of sunflower oil in skim milk. In contrast, L. lactis and L. viridescens could tolerate the increasing concentrations of sunflower oil and produced higher CLA. Overall, L. brevis extends a possibility to be used as a direct-fed microbial for ruminants to increase the CLA content in milk, however, in vivo trials are needed for validation of results obtained.     

Reconstructing the clostridial n-butanol metabolic pathway in Lactobacillus brevis

A Lactobacillus brevis strain with the ability to synthesize butanol from glucose was constructed by metabolic engineering. The genes crt, bcd, etfB, etfA, and hbd, composing the bcs-operon, and the thl gene encode the enzymes of the lower part of the clostridial butanol pathway (crotonase, butyryl-CoA-dehydrogenase, two subunits of the electron transfer flavoprotein, 3-hydroxybutyryl-CoA dehydrogenase, and thiolase) of Clostridium acetobutylicum. They were cloned into the Gram-positive/Gram-negative shuttle plasmid vector pHYc. The two resulting plasmids pHYc-thl-bcs and pHYc-bcs (respectively, with and without the clostridial thl gene) were transferred to Escherichia coli and L. brevis. The recombinant L. brevis strains were able to synthesize up to 300 mg l⁻¹ or 4.1 mM of butanol on a glucose-containing medium. A L. brevis strain carrying the clostridial bcs-operon has the ability to synthesize butanol with participation of its own thiolase, aldehyde dehydrogenase, and alcohol dehydrogenase. The particular role of the enzymes involved in butanol production and the suitability of L. brevis as an n-butanol producer are discussed.