Search

It has been planned to minimize the yield and quality impairment of the seed corn, which is strategically important in the world, by pests under storage conditions with a biological product produced with a biotechnological approach. In this context, the present study aimed to control the maize weevil Sitophilus zeamais, known as a warehouse pest, using a nanoformulation. In the study, the chitinase enzyme from Lactobacillus coryniformis was purified first using ammonium sulfate precipitation and then by using the HiTrap Capto DEAE column, and the molecular mass of the purified enzyme was determined to be ~ 33 kDa, and the optimum pH and the values as pH 6.0 and 65-75 °C, respectively. Five different doses of nanoformulation (2, 4, 6, 8 and 10 mg/L) were applied to corn grains by the spraying method with three repetitions so that the insect can ingest the formulation through feeding. The effects of the applications on the death rate and mean time of death of Sitophilus zeamais were determined. According to these findings, it was concluded that the best practice was nanoformulation with 6 mg/L, considering both the mortality rate (100%) and the average death time (2.4 days). Chitinase from L. coryniformis is a promising candidate for corn lice control and management., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

A study was conducted on broiler birds for 42 days to determine the effect of feeding azolla along with direct-fed microbial (DFM) on growth performance, nutrient utilization, biochemical parameters and carcass characteristics. A total of 360-day-old male broiler chicks were divided into 3 groups and 12 replicates with 10 chicks per replicate, according to complete randomized block design. One group was fed a diet containing 2.5% azolla (A) and another was fed a diet containing 2.5% azolla, with direct-fed microbial (A + DFM), viz. L. plantarum and L. rhamnosus, at the concentration of 13.4 × 10 8 and 1.52 × 10 8  CFU per mL, respectively, mixed in the daily quota of feed. The control group (CON) was fed a basal diet without azolla and DFM. Azolla fed alone and with DFM did not affect growth performance and feed conversion ratio (FCR) of birds during pre-starter and starter phase; however, significantly (P < 0.05) lower weight gain and higher FCR were observed during finisher period, resulting in an impaired overall FCR. Decreased (P < 0.05) plasma cholesterol and increased (P < 0.05) tibial calcium content were observed in birds fed azolla with DFM. The highest value (P < 0.05) of carcass characteristics like gizzard weight, breast muscle yield and lower meat pH were recorded in the birds fed azolla in combination with DFM, followed by birds fed azolla alone. In conclusion, azolla feeding at 2.5% level shows positive effect on breast muscle yield and gizzard weight of broiler which can be enhanced upon adding DFM to azolla-based diet.

Biofilm-associated bacterial infections represent one of the major threats to modern medical treatments. Bacteria encased in biofilm matrix are more resistant towards antimicrobials and thus the capability of microbes to persist and nurture in a biofilm seems to be the foremost aspect of pathogenesis and therapeutic failure. Therefore, there is a pressing demand for new drugs active against microbial biofilms. In the current study, anti-biofilm potential of Lactobacillus spp. cell-free supernatants (CFSs) against Cronobacter sakazakii and Listeria monocytogenes was characterized using crystal violet staining and MTT assay. CFSs of goat milk origin lactobacilli not only prevented biofilm formation but also disrupted preformed biofilms. Neutralized and heat-treated preparations of Lactobacillus CFSs also inhibited biofilm formation by test pathogens. The results were quantitatively confirmed by light and fluorescent microscopy observations. Biofilms developed under static conditions displayed typical compact microcolonies with uniform distribution over the surface, while upon CFS challenge, biofilms were disrupted with presence of dead cells. These findings highlight the anti-biofilm potency of Lactobacillus spp. strains of goat milk origin and their potential application in food industries.

The natural antioxidant agent is urgently needed to prevent the negative effects of newly generated free radicals and chronic disorders. Recently, the microbial exopolysaccharide (EPS) is currently used as a potential biopolymer due to its unique biological characteristics. In this study, the biological potential was carried out on the EPSs produced by Lactobacillus reuteri SHA101 (EPS-lr) and Lactobacillus vaginalis SHA110 (EPS-lvg) isolated from gut cecum samples of healthy poultry birds (hen). As results, the EPS-lr and EPS-lvg showed the emulsifying activity of 37.8 ± 1.6% and 27.8 ± 0.5% after the 360 h, respectively. The scanning electron microscopy analysis of EPS-lr and EPS-lvg demonstrated a smooth surface with a compact structure. The both EPSs exhibited strong antibacterial activity against E. coli and Salmonella typhimurium in vitro. In additions, at 4 mg/mL concentration, the EPS-lr and EPS-lvg samples showed potent antioxidant activity regarding hydroxyl radical DPPH (2,2-diphenyl-1-picrylhydrazyl) radical, superoxide anion radical and reducing power at OD 700 nm . Furthermore, the EPS-lr and EPS-lvg (600 μg/mL) possessed antitumor activity against colon cancer (Caco-2) cell after 72 h. The results suggested that these EPSs would have great potential in the application of antitumor and antioxidant foods, biomedicine, and pharmaceutics.

The present study investigated skimmed milk and alginate-based encapsulation for protection of a probiotic strain, Lactobacillus gastricus BTM7 during storage and exposure to simulated gastrointestinal conditions. The investigations have revealed that coating with skimmed milk and alginate in a ratio of 1:1 resulted in highest encapsulation efficiency of 94% (p < 0.05) with approximately 1 log reduction in viable cell count and 90% release of encapsulated cells in 90 min. This formulation resulted in 5-fold higher survival of bacteria during storage at refrigeration for 21 days (p < 0.05). The encapsulation of L. gastricus BTM7 provided better protection at the pH of gastric juice or pancreatic conditions with 4- and 9-fold increase in survivability after 2 h of incubation. The principal component analysis (PCA) revealed the potential of skimmed milk supplementation to alginate (1:1) to enhance survival of probiotic strain under refrigerated storage, a process that can be safely incorporated into dairy products.

Lactobacillus farciminis CIP 103136 is a bacterial strain with recognized probiotic properties. However, the mechanisms underlying such properties have only been partially elucidated. In this study, we isolated and purified a cell-wall associated polysaccharide (CWPS), and evaluated its biological role in vitro. The structure of CWPS and responses from stimulation of (i) human macrophage-like THP-1 cells, (ii) human embryonal kidney (HEK293) cells stably transfected with Toll-like receptors (TLR2 or TLR4) and (iii) human colonocyte-like T84 intestinal epithelial cells, upon exposure to CWPS were studied. The structure of the purified CWPS from L. farciminis CIP 103136 was analyzed by nuclear magnetic resonance (NMR), MALDI-TOF-TOF MS, and methylation analyses in its native form and following Smith degradation. It was shown to be a novel branched polysaccharide, composed of linear backbone of trisaccharide repeating units of: [→6αGlcpNAc1 → 4βManpNAc1 → 4βGlcpNAc1→] highly substituted with single residues of αGlcp, αGalp and αGlcpNAc. Subsequently, the lack of pro- or anti-inflammatory properties of CWPS was established on macrophage-like THP-1 cells. In addition, CWPS failed to modulate cell signaling pathways dependent of TLR2 and TLR4 in transfected HEK-cells. Finally, in T84 cells, CWPS neither influenced intestinal barrier integrity under basal conditions nor prevented TNF-α/IFN-γ cytokine-mediated epithelium impairment.

Lactobacillus mucosae strain AN1 isolated from sheep milk and characterized for its probiotic suitability. In vitro evaluation of critical gut endurance properties of this strain were assessed by different screening methods such as bile salt, gastric acid, lysozyme tolerance assays, hemolytic, cholesterol reduction properties, and HT-29 cell line adhesion assay. Antibacterial peptide from this strain was purified using ammonium sulphate precipitation, gel filtration chromatography and reverse-phase HPLC. The molecular mass of peptides was determined by Tricine-SDS-PAGE and confirmed by matrix-assisted laser desorption ionization-time of flight mass spectroscopy (MALDI-TOF-MS). Purified peptide was named as AN1 having a molecular mass of 10.66 kDa. Helical structures of peptide were determined using circular dichroism spectroscopy. Stability of peptide AN1 towards different parameters such as pH, temperature, organic solvents, proteolytic, and glycolytic enzymes was also analyzed.

Nine wild Lactobacillus strains, namely Lactobacillus plantarum 53, Lactobacillus fermentum 56, L. fermentum 60, Lactobacillus paracasei 106, L. fermentum 250, L. fermentum 263, L. fermentum 139, L. fermentum 141, and L. fermentum 296, isolated from fruit processing by-products were evaluated in vitro for a series of safety, physiological functionality, and technological properties that could enable their use as probiotics. Considering the safety aspects, the resistance to antibiotics varied among the examined strains, and none of the strains presented hemolytic and mucinolytic activity. Regarding the physiological functionality properties, none of the strains were able to deconjugate bile salts; all of them presented low to moderate cell hydrophobicity and were able to autoaggregate, coaggregate with Listeria monocytogenes and Escherichia coli, and antagonize pathogenic bacteria. Exposure to pH 2 sharply decreased the survival of the examined strains after 1- or 2-h exposure; variable decreases were noted after 3-h exposure to pH 3. Overall, exposure to pH 5 and to bile salts (0.15, 0.3, and 1%) did not decrease the strains' survival. Examined strains presented better ability to survive from the exposure to simulated gastrointestinal conditions in laboratorial media and milk than in grape juice. Considering the technological properties, all the strains were positive for proteolytic activity and EPS and diacetyl production, and most of them had good tolerance to 1-4% NaCl. These results indicate that wild Lactobacillus strains isolated from fruit processing by-products could present performance compatible with probiotic properties and technological features that enable the development of probiotic foods with distinct characteristics.

Kefir is a natural fermentation agent composed of various microorganisms. To address the mechanism of kefir grain formation, we investigated the microbial role in forming kefir biofilms. The results showed that a biofilm could be formed in kefir-fermented milk and the biofilm forming ability reached the maximum at 13 days. The strains Kluyveromyces marxianus, Lactococcus lactis, Leuconostoc mesenteroides, Lactobacillus kefiri, Lactobacillus sunkii and Acetobacter orientalis were isolated from kefir biofilms by the streak-plate method. These microorganisms were analysed with respect to biofilm forming properties, including their surface characterisation (hydrophobicity and zeta potentials) and the microbial aggregation. The results indicated that Klu. marxianus possessed the strongest biofilm forming properties with the strongest hydrophobicity, lowest zeta potential and greatest auto-aggregation ability. When Klu. marxianus and Ac. orientalis were co-cultured with kefir LAB strains respectively, it was found that mixing Klu. marxianus with Lb. sunkii produced the highest co-aggregation ability. These results elucidated the mechanism of kefir biofilm formation and the microorganisms involved.

Industrial ethanol fermentation is subject to bacterial contamination that causes significant economic losses in ethanol fuel plants. Chronic contamination has been associated with biofilms that are normally more resistant to antimicrobials and cleaning efforts than planktonic cells. In this study, contaminant species of Lactobacillus isolated from biofilms (source of sessile cells) and wine (source of planktonic cells) from industrial and pilot-scale fermentations were compared regarding their ability to form biofilms and their sensitivity to different antimicrobials. Fifty lactobacilli were isolated and the most abundant species were Lactobacillus casei, Lactobacillus fermentum and Lactobacillus plantarum. The majority of the isolates (87.8%) were able to produce biofilms in pure culture. The capability to form biofilms and sensitivity to virginiamycin, monensin and beta-acids from hops, showed inter- and intra-specific variability. In the pilot-scale fermentation, Lactobacillus brevis, L. casei and the majority of L. plantarum isolates were less sensitive to beta-acids than their counterparts from wine; L. brevis isolates from biofilms were also less sensitive to monensin when compared to the wine isolates. Biofilm formation and sensitivity to beta-acids showed a positive and negative correlation for L. casei and L. plantarum, respectively.

In the majority of Latin-American countries, including Argentina, there is a limited availability of vaginal bioproducts containing probiotics in the market. In addition, the conventional treatments of genital tract infections in women represent a high cost to the public health systems. The future development of this type of bioproducts that employ specific lactobacilli strains would not only have a meaningful impact on women's health but would also represent a significant challenge to the pharmaceutical industry. The aims of the work described in this paper were (i) to study different pharmaceutical formulations of vaginal ovules containing Lactobacillus fermentum L23 and L. rhamnosus L60, to determine in which formulation lactobacilli viability was sustained for longer time and (ii) to evaluate if probiotic strains maintained both the antimicrobial activity and biofilm-producing ability after being recovered from the ovules. In this study, we developed and characterized three pharmaceutical formulations containing different glycerol amounts and specific lactobacilli strains. Three relevant parameters, cell viability, antimicrobial activity, and biofilm production, by lactobacilli recovered from the ovules were tested. Although the viability of L23 and L60 strains was mainly influenced by high ovule's glycerol proportion, they survived at 4 °C during the 180 days. Both lactobacilli's antimicrobial activity and biofilm-producing ability were maintained for all treatments. In conclusion, employing a much reduced number of components, we were able to select the most suitable pharmaceutical formulation which maintained not only lactobacilli viability for a long period of time but also their antimicrobial activity and biofilm-producing ability.

This study investigated the influence of aeration and minimal medium conditions on antioxidant and antibacterial activities of 21 probiotic Lactobacillus strains isolated from dairy products. The probiotic potential of the isolates was evaluated by pH and bile tolerance. Random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) was used to confirm the phenotypic identification of isolates. Antioxidant producer isolates were screened by resistance to reactive oxygen species (ROS). The antioxidant and antibacterial activities of extracellular materials after 48 h fermentation with antioxidative strains were determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and broth microdilution assays, respectively. The results indicate that the antioxidant capacity of supernatants was increased by using of both minimal medium and agitation. The antibacterial activity was increased in minimal medium, but there has nearly no change in the antibacterial properties by using both agitation and minimal medium. The maximum antibacterial activity was observed during mid-exponential phase until the beginning of the early-stationary phase, but the maximum antioxidant activity was detected at the stationary growth phase. There is a significant relationship between antioxidant and antibacterial activities of the cell-free probiotic extracts, and their production rates are closely related to the fermentation type. The bioactive materials from probiotics could be extracted in a large amount at an appropriate time under a suitable condition.

Lactobacillus strains can synthesize capsular polysaccharides (CPS), which are important substances in the dairy industry-they exhibit many important technological as well as health-promoting properties. Technological advancements have made it possible to detect bacterial capsules using costly and labor-intensive methods, such as serological reactions, molecular genetic techniques, and electron microscopy. Light microscopy, which is the method of interest in this paper, is one of the most widely accessible and cheapest techniques. CPS may be observed under a light microscope after staining bacterial cells and the background with a basic die and an acidic die, respectively (negative-positive staining), with the capsules remaining transparent. The literature offers many polysaccharide staining methods, but due to the considerable structural diversity of CPS and possible dye-capsule interactions, a suitable staining technique should be carefully selected for each strain. The current study showed that not all methods adequately reveal Lactobacillus CPS, with the most effective ones being those proposed by Hiss and Maneval.

Bacteriocin TSU4 is a novel antimicrobial peptide isolated from Catla catla gut isolate Lactobacillus animalis TSU4. It has been reported for its potential antimicrobial activity against fish pathogens and food spoilage bacteria. In vivo safety evaluation is necessary to determine its immunogenicity, toxicity, and importance in real-life applications. The present study was designed to evaluate the immunogenicity, acute and sub-chronic toxicity of bacteriocin TSU4 in BALB/c mice to ensure its safety in industrial application. Male BALB/c mice were administered intraperitoneally for immunogenicity assessment, by oral gavage with 50, 100, and 200 mg/kg/body weight for acute test and 0.5 mg/kg/day dose of bacteriocin TSU4 for sub-chronic toxicity test. Neither mortality nor any infections were observed during experimental period. There was no major increase in antibody titer during the immunogenicity test, and no mortality was observed during acute or sub-chronic toxicity tests. The LD 50 value of bacteriocin TSU4 was found to be higher than 200 ± 0.45 mg/kg. No significant change in the serum biochemical markers, histopathological analysis and visual observation in spleen sizes was observed. These findings revealed that bacteriocin TSU4 is a non-immunogenic, safe, non-toxic, and could be a potential candidate for industrial applications in food preservation and aquaculture industries.

We studied as hydrogen peroxide, lactic acid, or surfactants from clinical isolates of vaginal lactobacilli and cell-free supernatants from probiotic strain LCR35 can influence on the sensitivity of opportunistic bacteria to antibiotics. We found that the most effective in increasing sensitivity to antibiotics were hydrogen peroxide and surfactants or their combination but no lactic acid. In some cases, the effect of the composition of hydrogen peroxide and surfactants was clearly higher than the sum of effects of these substances alone. With using of the supernatant of LCR35 was shown that the combination of surfactant and lactate has greater effect compared with surfactants alone. In concluding, metabolites of vaginal lactobacilli are suitable for the role of "antibiotic assistants" and it can help solve the problems the antibiotic resistance.

The lactic acid bacteria (LAB) microbiota of Saudi chicken ceca was determined. From 60 samples, 204 isolates of lactic acid bacteria were obtained. Three isolates produced antimicrobial activities against Campylobacter jejuni, Listeria monocytogenes, and Bacillus subtilis. The isolate DN317, which had the highest activity against Campylobacter jejuni ATCC 33560, was identified as Lactobacillus curvatus (GenBank accession numbers: KX353849 and KX353850). Full inhibitory activity was observed after a 2-h incubation with the supernatant at pH values between 4 and 8. Only 16% of the activity was conserved after a treatment at 121 °C for 15 min. The use of proteinase K, pepsin, chymotrypsin, trypsin, papain, and lysozyme drastically reduced the antimicrobial activity. However, lipase, catalase, and lysozyme had no effect on this activity. The active peptide produced by Lactobacillus curvatus DN317 was purified by precipitation with an 80% saturated ammonium sulfate solution, and two steps of reversed phase HPLC on a C18 column. The molecular weight of this peptide was 4448 Da as determined by MALDI-ToF. N-terminal sequence analysis using Edman degradation revealed 47 amino acid residues (UniProt Knowledgebase accession number C0HK82) revealing homology with the amino acid sequences of sakacin P and curvaticin L442. The antimicrobial activity of the bacteriocin, namely curvaticin DN317, was found to be bacteriostatic against Campylobacter jejuni ATCC 33560. The use of microbial antagonism by LAB is one of the best ways to control microorganisms safely in foods. This result constitutes a reasonable advance in the antimicrobial field because of its potential applications in food technology.

Oxidative stress and tissue destruction are at the heart of periodontal diseases. The dental research area is geared toward the prevention of free radicals by nutrient antioxidants. Lactic acid bacteria (LAB) have recently attracted attention in alternative dental therapies. We aimed at highlighting the antioxidative property of Lactobacilli and Bifidobacterium strains and at determining their protective effect on gingival fibroblasts (GFs). Two Lactobacilli and 2 Bifidobacterium strains were screened for their exopolysaccharide (EPSs) production. Antioxidative assays were conducted by spectrophotometer analysis. Resistance to different concentrations of hydrogen peroxide (H2O2) was determined by the serial dilution technique. The protective effect of strains on GFs on hydrogen peroxide exposure was also examined by a new trypan blue exclusion assay method. Bifidobacterium breve A28 showed the highest EPS production (122 mg/l) and remarkable antioxidant activity, which were demonstrated by its ability to scavenge 72% α,α-diphenyl-1-picrylhydrazyl free radical and chelate 88% of iron ion, respectively. Inhibition of lipid peroxidation was determined as 71% for the A28 strain. We suggest that LAB with antioxidative activity could be a good natural therapy agent for periodontal disorders.

Bacillus cereus is an endospore-forming, Gram-positive bacterium able to cause foodborne diseases. Lactic acid bacteria (LAB) are known for their ability to synthesize organic acids and bacteriocins, but the potential of these compounds against B. cereus has been scarcely documented in food models. The present study has examined the effect of the metabolites produced by Lactobacillus johnsonii CRL1647 and Enterococcus faecium SM21 on the viability of select B. cereus strains. Furthermore, the effect of E. faecium SM21 metabolites against B. cereus strains has also been investigated on a rice food model. L. johnsonii CRL1647 produced 128 mmol/L of lactic acid, 38 mmol/L of acetic acid and 0.3 mmol/L of phenyl-lactic acid. These organic acids reduced the number of vegetative cells and spores of the B. cereus strains tested. However, the antagonistic effect disappeared at pH 6.5. On the other hand, E. faecium SM21 produced only lactic and acetic acid (24.5 and 12.2 mmol/L, respectively) and was able to inhibit both vegetative cells and spores of the B. cereus strains, at a final fermentation pH of 5.0 and at pH 6.5. This would indicate the action of other metabolites, different from organic acids, present in the cell-free supernatant. On cooked rice grains, the E. faecium SM21 bacteriocin(s) were tested against two B. cereus strains. Both of them were significantly affected within the first 4 h of contact; whereas B. cereus BAC1 cells recovered after 24 h, the effect on B. cereus 1 remained up to the end of the assay. The LAB studied may thus be considered to define future strategies for biological control of B. cereus.

Bacteriocin B231 produced by Lactobacillus pentosus, isolated from an artisanal raw cow's milk protected designation of origin Portuguese cheese, is a small protein with an apparent relative mass of about 5 kDa and active against a large number of Listeria monocytogenes wild-type strains, Listeria ivanovii and Listeria innocua. Bacteriocin B231 production is highly dependent on the type of the culture media used for growth of Lact. pentosus B231. Replacement of glucose with maltose yielded the highest bacteriocin production from eight different carbon sources. Similar results were recorded in the presence of combination of glucose and maltose or galactose. Production of bacteriocin B231 reached maximal levels of 800 AU/ml during the stationary phase of growth of Lact. pentosus B231 in MRS broth at 30 °C. Bacteriocin B231 (in cell-free supernatant) was sensitive to treatment with trypsin and proteinase K, but not affected by the thermal treatment in range of 55-121 °C, or freezing (-20 °C). Bacteriocin production and inhibitory spectrum were evaluated. Gene encoding plantaricin S has been detected in the genomic DNA. Virulence potential and safety of Lact. pentosus B231 were assessed by PCR targeted the genes gelE, hyl, asa1, esp, cylA, efaA, ace, vanA, vanB, hdc1, hdc2, tdc and odc. The Lact. pentosus B231 strains harbored plantaricin S gene, while the occurrence of virulence, antibiotic resistance and biogenic amine genes was limited to cytolysin, hyaluronidase, aggregation substance, adhesion of collagen protein, gelatinase, tyrosine decarboxylase and vancomycin B genes.

The human gut represents a highly complex ecosystem, which is densely colonized by a myriad of microorganisms that influence the physiology, immune function and health status of the host. Among the many members of the human gut microbiota, there are microorganisms that have co-evolved with their host and that are believed to exert health-promoting or probiotic effects. Probiotic bacteria isolated from the gut and other environments are commercially exploited, and although there is a growing list of health benefits provided by the consumption of such probiotics, their precise mechanisms of action have essentially remained elusive. Genomics approaches have provided exciting new opportunities for the identification of probiotic effector molecules that elicit specific responses to influence the physiology and immune function of their human host. In this review, we describe the current understanding of the intriguing relationships that exist between the human gut and key members of the gut microbiota such as bifidobacteria and lactobacilli, discussed here as prototypical groups of probiotic microorganisms.

Since the presence of S-layer protein conditioned the autoaggregation capacity of some strains of Lactobacillus kefir, S-layer proteins from aggregating and non-aggregating L. kefir strains were characterized by immunochemical reactivity, MALDI-TOF spectrometry and glycosylation analysis. Two anti-S-layer monoclonal antibodies (Mab5F8 and Mab1F8) were produced; in an indirect enzyme-linked immunosorbent assay Mab1F8 recognized S-layer proteins from all L. kefir tested while Mab5F8 recognized only S-layer proteins from aggregating strains. Periodic Acid-Schiff staining of proteins after polyacrylamide gel electrophoresis under denaturing conditions revealed that all L. kefir S-layer proteins tested were glycosylated. Growth of bacteria in the presence of the N-glycosylation inhibitor tunicamycin suggested the presence of glycosydic chains O-linked to the protein backbone. MALDI-TOF peptide map fingerprint for S-layer proteins from 12 L. kefir strains showed very similar patterns for the aggregating strains, different from those for the non-aggregating ones. No positive match with other protein spectra in MSDB Database was found. Our results revealed a high heterogeneity among S-layer proteins from different L. kefir strains but also suggested a correlation between the structure of these S-layer glycoproteins and the aggregation properties of whole bacterial cells.

Six lactobacillus species and 4 clones of one of them were studied in order to clear out the ratio between the adhesion capacities of concanavalin A-reactive glycoprotein adhesins on the surface of the bacterial cell and glycoprotein adhesins released into the broth during culturing in liquid nutrient media. The adhesive activity of cultures is largely determined by the strain rather than species appurtenance. Elimination of glycoprotein adhesins from the bacterial cell and their antagonistic activity towards Candida albicans were demonstrated in specific interactions of glycoprotein adhesins with immune serum and concanavalin A.

We examined production of the protein-lipoteichoic complex detectable by concanavalin A in six lactobacillus strains. A correlation was found between detection of this complex by both reaction with concanavalin A and agglutination with strain-specific antiserum. The cultures were characterized by expression of different types of adhesins. Among them, strains were differentiated with low adhesion activity and intensive production of the protein-lipoteichoic complex and strains with wide adhesin spectrum not producing the complex. We assume that a combination of lactobacillus variants differing in production of the protein-lipoteichoic complex and adhesion potency can be a basis of efficient probiotic preparation.

Strains of Enterococcus faecalis and Lactobacillus sake have been found to express lantibiotics with unusual properties. The enterococcal lantibiotic is unusual in that it consists of two dissimilar subunits, both putatively containing modifications consistent with those found in other lantibiotics. The enterococcal lantibiotic is also unusual in the number of proteolytic steps involved in secretion signal removal and activation. Moreover, it has been observed to contribute to enterococcal disease in humans and in animal models. Structural studies of lactocin S, expressed by a strain of L. sake highlight unique properties including the presence of D-alanine within its structure, and a protease putatively responsible for lactocin S secretion signal peptide removal which, itself, lacks a signal or propeptide sequence. Despite the unusual properties of each of these lantibiotics, the operons encoding each, and accompanying auxiliary functions, are collinear suggesting a common ancestry. The accretion of interdigitating DNA sequences between genes encoded within the lactocin S determinant are unique to that determinant, however, and are of unknown function.

Fourteen of 200 Lactobacillus isolates from African fermented foods, viz. 'wara', 'kenkey', 'ugba', 'ogi', 'kunuzarki', 'fufu' and 'iru' were found to produce bacteriocins against L. plantarum and only three bacteriocinogenic isolates inhibited some of the food pathogens. Plasmid analysis of the 14 bacteriocin-producing lactobacilli showed that only 5 isolates harbored plasmids ranging in size from 3.1 to 55.5 kb.