Resistance Of Lactic Acid Bacteria Research Articles

STUDY OF ANTIBIOTIC RESISTANCE OF LACTIC ACID BACTERIA ISOLATED FROM DAIRY PRODUCTS

In this study, cultures of lactic acid bacteria (3M, 3K, 7K, 9K, 10K and 11K) isolated from mare's milk and koumiss were examined in order to assess their resistance to various antibiotics. Discs impregnated with gentamicin (120 mcg), azithromycin (15 mcg), ceftriaxone (30 mcg), cefuroxime (30 mcg) and chloramphenicol (30 mcg) were used.The data obtained showed that strains 3K, 10K and 11K demonstrated the greatest resistance to gentamicin, similarly, strains 10K and 11K showed high resistance to azithromycin. For ceftriaxone and cefuroxime, strains 11K and 10K demonstrated the greatest resistance. Strains 11K and 10K were the most resistant to chloramphenicol, while strain 3K was the most sensitive. In general, strains 3K and 3M showed the least resistance to most antibiotics, especially ceftriaxone and cefuroxime, which indicates their high sensitivity to these drugs. In contrast, strains 10K and 11K demonstrated the greatest resistance, showing minimal suppression zones for most of the antibiotics studied.The obtained data can be used to develop and optimize probiotic drugs that take into account the resistance of lactic acid bacteria to antibiotics. This will increase the effectiveness of the use of probiotics in various foods and medicines, contributing to the maintenance of healthy intestinal microflora and strengthening the immune system.

Chickpeas’ Cooking Wastewater as an Alternative Source of Galacto-Oligosaccharides for Improving the Freeze-Dried Resistance of Lactic Acid Bacteria

Chickpeas’ Cooking Wastewater as an Alternative Source of Galacto-Oligosaccharides for Improving the Freeze-Dried Resistance of Lactic Acid Bacteria

Phenotypic and genotypic characterization of antimicrobial resistances reveals the effect of the production chain in reducing resistant lactic acid bacteria in an artisanal raw ewe milk PDO cheese

Antimicrobial resistance (AMR) is a significant public health threat, with the food production chain, and, specifically, fermented products, as a potential vehicle for dissemination. However, information about dairy products, especially raw ewe milk cheeses, is limited. The present study analysed, for the first time, the occurrence of AMRs related to lactic acid bacteria (LAB) along a raw ewe milk cheese production chain for the most common antimicrobial agents used on farms (dihydrostreptomycin, benzylpenicillin, amoxicillin and polymyxin B). More than 200 LAB isolates were obtained and identified by Sanger sequencing (V1-V3 16S rRNA regions); these isolates included 8 LAB genera and 21 species. Significant differences in LAB composition were observed throughout the production chain (P ≤ 0.001), with Enterococcus (e.g., E. hirae and E. faecalis) and Bacillus (e.g., B. thuringiensis and B. cereus) predominating in ovine faeces and raw ewe milk, respectively, along with Lactococcus (L. lactis) in whey and fresh cheeses, while Lactobacillus and Lacticaseibacillus species (e.g., Lactobacillus sp. and L. paracasei) prevailed in ripened cheeses. Phenotypically, by broth microdilution, Lactococcus, Enterococcus and Bacillus species presented the greatest resistance rates (on average, 78.2 %, 56.8 % and 53.4 %, respectively), specifically against polymyxin B, and were more susceptible to dihydrostreptomycin. Conversely, Lacticaseibacillus and Lactobacillus were more susceptible to all antimicrobials tested (31.4 % and 39.1 %, respectively). Thus, resistance patterns and multidrug resistance were reduced along the production chain (P ≤ 0.05). Genotypically, through HT-qPCR, 31 antimicrobial resistance genes (ARGs) and 6 mobile genetic elements (MGEs) were detected, predominating Str, StrB and aadA-01, related to aminoglycoside resistance, and the transposons tnpA-02 and tnpA-01. In general, a significant reduction in ARGs and MGEs abundances was also observed throughout the production chain (P ≤ 0.001). The current findings indicate that LAB dynamics throughout the raw ewe milk cheese production chain facilitated a reduction in AMRs, which has not been reported to date.

The influence of low-temperature resistant lactic acid bacteria on the enhancement of quality and the microbial community in winter Jerusalem Artichoke (Helianthus tuberosus L.) silage on the Qinghai-Tibet Plateau.

Jerusalem Artichoke (Helianthus tuberosus L.), an emerging "food and fodder" economic crop on the Qinghai-Tibet Plateau. To tackle problems such as incomplete fermentation and nutrient loss occurring during the low-temperature ensilage of Jerusalem Artichokes in the plateau's winter, this study inoculated two strains of low-temperature resistant lactic acid bacteria, Lactobacillus plantarum (GN02) and Lactobacillus brevis (XN25), along with their mixed components, into Jerusalem Artichoke silage material. We investigated how low-temperature resistant lactic acid bacteria enhance the quality of low-temperature silage fermentation for Jerusalem Artichokes and clarify its mutual feedback effect with microorganisms. Results indicated that inoculating low-temperature resistant lactic acid bacteria significantly reduces the potential of hydrogen and water-soluble carbohydrates content of silage, while increasing lactic acid and acetic acid levels, reducing propionic acid, and preserving additional dry matter. Inoculating the L. plantarum group during fermentation lowers pH and propionic acid levels, increases lactic acid content, and maintains a dry matter content similar to the original material. Bacterial community diversity exhibited more pronounced changes than fungal diversity, with inoculation having a minor effect on fungal community diversity. Within the bacteria, Lactobacillus remains consistently abundant (>85%) in the inoculated L. plantarum group. At the fungal phylum and genus levels, no significant changes were observed following fermentation, and dominant fungal genera in all groups did not differ significantly from those in the raw material. L. plantarum exhibited a positive correlation with lactic acid and negative correlations with pH and propionic acid. In summary, the inoculation of L. plantarum GN02 facilitated the fermentation process, preserved an acidic silage environment, and ensured high fermentation quality; it is a suitable inoculant for low-temperature silage in the Qinghai-Tibet Plateau.

Effect of high pressure processing and water activity on pressure resistant spoilage lactic acid bacteria (Latilactobacillus sakei) in a ready-to-eat meat emulsion model

The main use of High Pressure Processing (HPP) in food processing is microorganism inactivation, and studies demonstrated that the characteristics of matrix and microorganisms can interfere on it. As the behavior of lactic acid bacteria exposed to different water activity (aw) levels in a meat product is still unclear, this study aimed to determine the effect of pressure, time, and aw to inactivate Latilactobacillus sakei, a pressure resistant lactic acid bacteria (LAB) in a meat emulsion model through a response surface methodology. The meat emulsion model was designed with adjusted aw (from 0.940 to 0.960) and was inoculated with a pressure resistant LAB and processed varying pressure (400-600 MPa) and time (180–480 s), following the Central Composite Rotational Design (CCRD). The inactivation of the microorganism ranged from 0.99 to 4.12 UFC/g depending on the applied condition. At studied conditions, according to the best fitting and most significant polynomial equation (R2 of 89.73 %), in a meat emulsion model, aw had no influenced on HPP inactivation on LAB (p > 0.05) and only pressure and holding time had significative impact on it. The results of experimental validation of the mathematical model were satisfactory, confirming the suitability of the model. The information obtained in the present study stands out the matrix, microorganism and process effects at HPP efficiency. The answers obtained support food processors in product development, process optimization and food waste reduction.

Antimicrobial Resistance of Lactic Acid Bacteria from Nono, a Naturally Fermented Milk Product.

Antimicrobial resistance (AMR) is one of the biggest threats to public health. The food chain has been recognised as a vehicle for transmitting AMR bacteria. However, information about resistant strains isolated from African traditional fermented foods remains limited. Nono is a traditional, naturally fermented milk product consumed by many pastoral communities across West Africa. The main aim of this study was to investigate and determine the AMR patterns of lactic acid bacteria (LAB) involved in the traditional fermentation of milk for Nono production, and the presence of transferable AMR determinants. One hundred (100) LAB isolates from Nono identified in a previous study as Limosilactobacillus fermentum, Lactobacillus delbrueckii, Streptococcus thermophilus, Streptococcus infantarius, Lentilactobacillus senioris, Leuconostoc pseudomesenteriodes, and Enterococcus thailandicus were investigated. The minimum inhibitory concentration (MIC) was determined for 18 antimicrobials using the micro-broth dilution method. In addition, LAB isolates were screened for 28 antimicrobial resistance genes using PCR. The ability of LAB isolates to transfer tetracycline and streptomycin resistance genes to Enterococcus faecalis was also investigated. The experiments revealed variable antimicrobial susceptibility according to the LAB isolate and the antimicrobial tested. The tetracycline resistance genes tet(S) and tet(M) were detected in isolates Ent. thailandicus 52 and S. infantarius 10. Additionally, aad(E) encoding resistance to streptomycin was detected in Ent. thailandicus 52. The conjugation experiments suggested that the tet(S) and aad(E) genes were transferable in vitro from isolate Ent. thailandicus 52 to Ent. faecalis JH2-2. Traditional fermented foods play a significant role in the diet of millions of people in Africa, yet their contribution to the burden of AMR is largely unknown. This study highlights that LAB involved in traditionally fermented foods could be potential reservoirs of AMR. It also underscores the relevant safety issues of Ent. thailandicus 52 and S. infantarius 10 for use as starter cultures as they carry transferable AMR genes. Starter cultures are an essential aspect of improving the safety and quality attributes of African fermented foods. However, AMR monitoring is an important safety aspect in the selection of starter cultures for improving traditional fermentation technologies.

Prevalence of antibiotic resistance in lactic acid bacteria isolated from traditional fermented Indian food products.

The online version contains supplementary material available at 10.1007/s10068-023-01305-1.

Microbiological Biodiversity of Regional Cow, Goat and Ewe Milk Cheeses Produced in Poland and Antibiotic Resistance of Lactic Acid Bacteria Isolated from Them.

(1) Unique sensory values of traditional and regional dairy products made them more and more popular among consumers. Lactic acid bacteria naturally occurring in these products can express antibiotic resistance and be a reservoir of antibiotic resistance genes (ARG) in the environment. The aim of the study was to characterize the microbial diversity of twenty regional cheeses produced from non-pasteurized cow, goat and ewe milk, and investigate the phenotypic and genotypic antibiotic resistance (AR) of lactic acid bacteria isolated from these products. (2) Conventional microbiological methods were applied for the enumeration of lactic acid bacteria (lactobacilli and lactococci) and their isolation, and for the enumeration of Enterococcus, Staphylococcus, Enterobacteriaceae and spores. The disc diffusion method was applied for phenotypic AR. The PCR-based methods were used for strain identification, microbiological diversity of cheeses (PCR-DGGE), and for AR gene detection. (3) Among 79 LAB isolates the most frequent species were L. plantarum (n = 18), Leuc. lactis (n = 17), Lc. lactis (n = 11), Leuc. mesenteroides (n = 9) and L. pentosus (n = 8). Additionally, by using the PCR-DGGE method, DNA of L. casei was found in nine products. Lactobacilli (5.63-8.46 log cfu/g) and lactococci (6.15-8.41 log cfu/g) predominated over Enterococcus (max. 4.89 log cfu/g), Staphylococcus (max. 4.18 log cfu/g), and Enterobacteriaceae (mostly up to 4.88 log cfu/g). Analysis of phenotypic resistance to tetracycline (30 µg), erythromycin (15 µg), and chloramphenicol (30 µg) showed that 29% of LAB isolates were resistant to one antibiotic, 8%-to two, and 12%-to all tested antibiotics. Antibiotic resistance genes (AGR) for tetracycline (tet(M), tet(L), tet(W)), erythromycin (erm(B)) and chloramphenicol (cat-TC) were detected in 30 (38%), 29 (36.7%) and 33 (43.4%) LAB isolates, respectively. Among 31 LAB isolates phenotypically susceptible to all tested antibiotics, only 5 (16%) had no ARGs. (4) The results obtained in our work shed light on the potential threat posed by the widespread presence of ARGs in LAB present in regional cheeses.

Effect of Trehalose and Lactose Treatments on the Freeze-Drying Resistance of Lactic Acid Bacteria in High-Density Culture.

Freeze-drying is a commonly used method in commercial preparations of lactic acid bacteria. However, some bacteria are killed during the freeze-drying process. To overcome this, trehalose and lactose are often used as protective agents. Moreover, high-density culture is an efficient way to grow bacterial strains but creates a hypertonic growth environment. We evaluated the effects of trehalose and lactose, as a primary carbon source or as an additive in fermentation, on the freeze-drying survival of Lactobacillus fermentum FXJCJ6-1, Lactobacillus brevis 173-1-2, and Lactobacillus reuteri CCFM1040. Our results showed that L. fermentum FXJCJ6-1 accumulated but did not use intracellular trehalose in a hypertonic environment, which enhanced its freeze-drying resistance. Furthermore, genes that could transport trehalose were identified in this bacterium. In addition, both the lactose addition and lactose culture improved the freeze-drying survival of the bacterium. Further studies revealed that the added lactose might exert its protective effect by attaching to the cell surface, whereas lactose culture acted by reducing extracellular polysaccharide production and promoting the binding of the protectant to the cell membrane. The different mechanisms of lactose and trehalose in enhancing the freeze-drying resistance of bacteria identified in this study will help to elucidate the anti-freeze-drying mechanisms of other sugars in subsequent investigations.

Prevalence of macrolide-lincosamide-streptogramin resistant lactic acid bacteria isolated from food samples.

Lactic acid bacteria (LAB) being a reservoir of antibiotic resistance genes, tend to disseminate antibiotic resistance that possibly pose a threat to human and animal health. Therefore, the study focuses on the prevalence of macrolide-lincosamide-streptogramin- (MLS) resistance among LAB isolated from various food samples. Diverse phenotypic and genotypic MLS resistance were determined among the LAB species (n = 146) isolated from fermented food products (n = 6) and intestine of food-producing animals (n = 4). Double disc, triple disc diffusion and standard minimum inhibitory concentration (MIC) tests were evaluated for phenotypic MLS resistance. Specific primers for MLS resistance genes were used for the evaluation of genotypic MLS resistance and gene expressions using total RNA of each isolate at different antibiotic concentrations. The isolates identified are Levilactobacillus brevis (n = 1), Enterococcus hirae (n = 1), Limosilactobacillus fermentum (n = 2), Pediococcus acidilactici (n = 3), Enterococcus faecalis (n = 1). The MIC tests along with induction studies displayed cMLSb, L phenotype, M phenotype, KH phenotype, I phenotype resistance among MLS antibiotics. Genotypic evaluation tests revealed the presence of ermB, mefA/E, msrA/B and msrC genes. Also, gene expression studies displayed increased level of gene expression to the twofold increased antibiotic concentrations. In the view of global health concern, this study identified that food samples and food-producing animals represent source of antibiotic resistant LAB that can disseminate resistance through food chain. This suggests the implementation of awareness in the use of antibiotics as growth promoters and judicious use of antibiotics in veterinary sectors in order to prevent the spread of antibiotic resistance.

Transcriptome analysis and functional gene identification reveals potential mechanisms of heat stress response of Lactiplantibacillus plantarum CGMCC8198

Lactiplantibacillus plantarum is an important probiotic bacterium and extensively applied to functional food. Its survival is strongly affected by the heat-shock process during manufacture. Acclimation is thought to be able to enhance bacteria resistance to heat stress. In this study, the results of transcriptomics and bioinformatics analysis showed that alcohol dehydrogenase adhE-like, phosphoribose-ATP pyrophosphatase hisE, flavodoxin ykuN, and dihydropterin aldolase folB might be related with heat resistance of L. plantarum CGMCC8198. Furthermore, after these genes were expressed in Escherichia coli, survival rate, hydrophobicity and membrane integrity of the recombinant bacteria under high temperature were also significantly improved. Besides, by screening the strains after multiple rounds of acclimation, a strain (XH) with better heat tolerance was obtained, and the results of qRT-PCR showed that these four genes, especially hisE, were upregulated in the acclimated strain when it was treated with high temperature. These findings indicated that adhE-like and some other potential genes could improve the heat resistance of lactic acid bacteria, and might be used as indicators for screening of heat-tolerant probiotics strains.

The function of uridine diphosphate glucose pyrophosphorylase in the lyophilization-stress response of Lactobacillus acidophilus

PurposeUridine diphosphate glucose pyrophosphorylase (UGPase) plays an important role in glucose metabolism, catalyzing the reversible formation and decomposition of UDP-glucose (UDPG). In previous work, we found that UGPase is a key enzyme in lyophilization response for Lactobacillus acidophilus (L. acidophilus). However, its function and regulatory mechanism in the freeze-drying stress response are unknown. Herein, the effect of UGPase on freeze-drying survival rate of Staphylococcus carnosus (S. carnosus) was studied.MethodsIn this work, the genes LBA1719 encoding UGPase of L. acidophilus ATCC4356 were inserted into plasmid pMG-36e to construct the recombinant plasmid pMG-LBA1719 and then overexpressed in S. carnosus; the control group was S. carnosus transformed by pMG-36e. The lyophilization-survival rate of overexpressed S. carnosus was determined, and the differentially expressed genes (DEGs) were analyzed by transcriptome to disclose the mechanism of LBA1719 in regulating the lyophilization-survival rate.ResultsCompared with the control group, the UGPase activities of the overexpressed S. carnosus increased by 35.49%, while the lyophilization-survival rates decreased by 11.17% (p < 0.05). Overexpression of LBA1719 decreased the expression of genes gapA, gapB, and pgiA in carbohydrate metabolism and dapA, dapB, and dapE in amino acid metabolism, significantly changing the physiological characteristics of S. carnosus and decreasing its lyophilization-survival rate.ConclusionIn summary, overexpression of UGPase accelerated the growth rate of S. carnosus and reduced its lyophilization-survival rates. GapA, gapB, pgiA, dapA, dapB, and dapE are vital to lyophilization protection in lactic acid bacteria (LAB). These findings provide new theoretical basis for analyzing the regulatory and molecular mechanisms of lyophilization resistance in LABs.

The production of preconditioned freeze-dried Oenococcus oeni primes its metabolism to withstand environmental stresses encountered upon inoculation into wine

Oenococcus oeni is the most resistant lactic acid bacteria species to the environmental stresses encountered in wine, particularly the acidity, presence of ethanol and phenolic compounds. Indigenous strains develop spontaneously following the yeast-driven alcoholic fermentation and may perform the malolactic fermentation whereby improving taste, aroma, and the microbial stability of wine. However, spontaneous fermentation is sometimes delayed, prolonged or incomplete. In order to better control its timing and quality, O. oeni strains are selected and developed to be used as malolactic starters. They are prepared under proprietary manufacturing processes to survive direct inoculation and are predominantly provided as freeze-dried preparations. In this study, we have investigated the physiological and molecular alterations occurring in O. oeni cells prepared by an industrial process that consists of preconditioning protocols and freeze-drying, and compared them to the same strain grown in a grape juice medium. We found that compared to cultured cells, the industrial production process improved survival under extreme conditions, i. e. at low pH or high tannin concentrations. In contrast, cultured cells resumed active growth more quickly and strongly than freeze-dried preparations in standard pH wines. A proteomic analysis showed that during the industrial production most non-essential metabolic processes are shut down and components of the general and the stringent stress response are upregulated. The presence of major components of the stress response facilitates protein homeostasis and physiological changes that further ensure the integrity of cells.

Incidence of virulence determinants and antibiotic resistance in lactic acid bacteria isolated from food products.

Background: Lactic acid bacteria (LAB) confer beneficial health effects in humans. However, the safety of these bacteria and their potential to spread resistance in the environment must be evaluated. Materials & methods: Fifty-three LAB were isolated from different food samplesand assessed for the prevalence of virulence determinants and antibiotic resistance profile. Results: Multiple resistance was reported for Lactobacillus brevis MIM04, having revealed phenotypic resistance to vancomycin (MIC >128μg/ml), ampicillin, cefotaxime, oxacillin and gentamicin. Virulence traits (cylA, gelE, esp and agg) were detected using specific primers. Enterococcus faecium CHE32, Lactobacillus plantarum CHE37 and E. faecium MLK68lack virulence genes, possess antimicrobial activity andsurvive in low pH and bile salt conditions. Conclusion: Isolated LAB revealed probiotic properties.

The Antibiotic resistance of lactic acid bacteria isolated from kefir made from Etawah goat milk

The objectives of the study were to determine the antibiotic resistance of Lactic Acid Bacteria (LAB) isolated from kefir made from Etawah goat milk. A total of 25 isolates were isolated from etawah goat milk, yogurt and kefir. LAB isolates were resistant to Ceftazidime (Caz, 100%), Ceftriaxone (Cro, 100%), Clindamycin (Da, 100%), Lincomycin (Li, 100%), Rifampicin (Rd, 100%) and Tobramycin (Tob, 100%). The bacteria were susceptible to Sulphamethoxazole-Trimethoprim (Sxt, 60%) and Tetracycline (Te, 40%). The percentage of antibiotic resistance of LAB was found to be in the range between 40 to 100%. The presence of antibiotic resistance in good bacteria may introduce the horizontal genetic transfer to bad bacteria which has the potential to disrupt human health.

Determination of probiotic characteristics and resistance to biological barriers under in vitro gastrointestinal conditions in goat cheese produced using microencapsulated probiotic bacteria

Abstract The method of microencapsulation has been performed on the probiotic microorganisms (Lactobacillus paracasei and Bifidobacterium longum), which are used in conjunction with the starter cultures in white cheese production from goat‘s milk. For this purpose, 3 types of microcapsules, namely, one containing the probiotic bacteria and another symbiotic microcapsule containing the probiotic bacteria and fructooligosaccharides have been obtained in the study and the cheese containing these microcapsules were produced. The cheese samples have been stored at +40C for 180 days and during storage, loss in viabiality that might be consisted at in-vitro conditions at gastrointestinal system is analyzed. The present study revealed that probiotic bacteria at different bile concentrations gained resistance during maturation, and the rate of resistance was higher in prebiotic and protein-supported microencapsulated probiotic bacteria. The resistance of lactic acid bacteria used in cheese production to gastric secretions was lower than that of probiotic bacteria. The determination of hydrophobicity of bacteria revealed that Bifidobacterium longum had the highest hydrophobicity level followed by Lactococcus, which forms the cheese culture, while Lactobacillus paracasei had the lowest level. It was determined that the microencapsulation method reduced the viability losses of probiotic microorganisms in the gastrointestinal tract.

Antibiotic Resistance of Lactic Acid Bacteria Isolated from Cambodian Fish Paste Product

Fish paste product is considered an important food in Cambodia. However, the status of antimicrobial susceptibility of microbes in this product are a concern. This study aimed to isolate lactic acid bacteria (LAB) from Cambodian fish paste and to investigate their resistant property of antibiotics. Fifteen LABs were isolated with cell forms of 14 as cocci and 1 as rods. Isolates of the bacteria were identified as Staphylococcus piscifermentans (14 strains) and Lactobacillus plantarum (1 strain). Using the disk diffusion method, the resistance was investigated of the 15 LAB isolate strains to eight clinically crucial antibiotics: penicillin (Pen), ampicillin (Amp), erythromycin (Ery), tetracycline (Tet), vancomycin (Van), streptomycin (Str), sulfamethoxazoletrimethoprim (Sul) and metronidazole (Met). It was found that all 15 LAB isolates were resistant to Met. One isolate strain was resistant to Pen, Amp, Tet, Str and Sul. Furthermore, 7 and 2 isolate strains were resistant to Tet and Van, respectively. All 15 isolate strains were sensitive to Str and Ery. The LAB isolate strains were sensitive to Pen, Amp, Sul (14 strains), Tet (6 strains) and Van (13 strains). These results showed that 14 of the LAB isolate strains were sensitive to 5 antibiotics (Pen, Amp, Ery, Str and Sul) and could be considered as strains for utilization as starter culture for fish fermentation. Additionally, these finding will be conduct to assess the antibiotic resistance incidences of LABs in Cambodian fermented foods.

Evaluation of Tetracycline Resistance and Determination of the Tentative Microbiological Cutoff Values in Lactic Acid Bacterial Species.

Lactic acid bacteria (LAB) are widely used as probiotics in the food industry owing to their beneficial effects on human health. However, numerous antibiotic resistance genes have been found in LAB strains, especially tetracycline resistance genes. Notably, the potential transferability of these genes poses safety risks. To comprehensively evaluate tetracycline resistance in LAB, we determined the tetracycline susceptibility patterns of 478 LAB strains belonging to four genera and eight species. By comparing phenotypes with genotypes based on genome-wide annotations, five tetracycline resistance genes, tet(M), tet(W/N/W), tet(L), tet(S), and tet(45), were detected in LAB. Multiple LAB strains without tetracycline resistance genes were found to be resistant to tetracycline at the currently recommended cutoff values. Thus, based on the minimum inhibitory concentrations of tetracycline for these LAB strains, the species-specific microbiological cutoff values for Lactobacillus (para)gasseri, Lactobacillus johnsonii, and Lactobacillus crispatus to tetracycline were first developed using the Turnidge, Kronvall, and eyeball methods. The cutoff values for Lactiplantibacillus plantarum were re-established and could be used to better distinguish susceptible strains from strains with acquired resistance. Finally, we verified that these five genes play a role in tetracycline resistance and found that tet(M) and tet(W/N/W) are the most widely distributed tetracycline resistance genes in LAB.

ANTIBIOTIC RESISTANCE OF LACTIC ACID BACTERY LEAVEN «VIVO PROBIOYOGURT»

Lactic acid bacteria play a key role in human microecology and biotechnology – form organoleptic characteristics of products, increase the nutritional, including biological value of functional foods. Natural resistance to antibiotics is one of the important factors that determine the probiotic properties of lacto- and bifidobacteria. Aim. Study of the antibiotic resistance of functionally active probiotic cultures of "VIVO probioyogurt" leaven to determine the possibility of using a fermented milk product, which is prepared on its basis, during antibiotic therapy to maintain and restore normal intestinal microflora. Methods. Pure cultures of lactic acid bacteria (LAB) were selected for the study: (Lactobacillus delbrueckii ssp., L. acidophilus, L.casei, L. rhamnosus, L.paracasei, Streptococcus thermophilus, Bifidobacterium lactis (2 strains), B. infantis), which are part of leaven "VIVO probioyogurt" the quality of which is confirmed by certificates of the International Organization for Standardization ISO 9001: 2008, as well as ISO 22000: 2005. The method of the experiment consisted of the following stages: preparation of nutrient media ("Lactobacagar", "Bifidoagar", glucose-peptone medium), working solutions of antibiotics; working suspension of LAB; suspensions of cultures (lacto- and bifidobacteria), cultivation LAB on elective nutrient media with the addition of antibiotics and evaluation of research results. Determination of antibiotic resistance of LAB was performed by the method of double dilutions. Results. The use of this technique enabled to establish the minimum inhibitory concentration (MIC) of antibiotics of different groups relative to the LAB. The results of the research were processed using a licensed computer program Microsoft Excel. Conclusions. Evaluation of the results of studies to determine the MIC of antibiotics – benzylpenicillin, azithromycin, lincomycin, gentamicin sulfate, ceftriaxone, norfloxacin, amoxil, streptomycin, tetracycline, erythromycin in relation to IBD; fermented milk product, which was prepared on the basis of this starter culture, it was advisable to use during antibiotic therapy to restore and maintain normal intestinal microflora.

Lactobacillus, Bifidobacterium and Lactococcus response to environmental stress: Mechanisms and application of cross-protection to improve resistance against freeze-drying.

The review deals with lactic acid bacteria in characterizing the stress adaptation with cross-protection effects, mainly associated with Lactobacillus, Bifidobacterium and Lactococcus. It focuses on adaptation and cross-protection in Lactobacillus, Bifidobacterium and Lactococcus, including heat shocking, cold stress, acid stress, osmotic stress, starvation effect, etc. Web of Science, Google Scholar, Science Direct, and PubMed databases were used for the systematic search of literature up to the year 2020. The literature suggests that a lower survival rate during freeze-drying is linked to environmental stress. Protective pretreatment under various mild stresses can be applied to lactic acid bacteria which may enhance resistance in a strain-dependent manner. We investigate the mechanism of damage and adaptation under various stresses including heat, cold, acidic, osmotic, starvation, oxidative and bile stress. Adaptive mechanisms include synthesis of stress-induced proteins, adjusting the composition of cell membrane fatty acids, accumulating compatible substances, etc. Next, we reveal the cross-protective effect of specific stress on the other environmental stresses. Freeze-drying is discussed from three perspectives including the regulation of membrane, accumulation of compatible solutes and the production of chaperones and stress-responsive proteases. The resistance of lactic acid bacteria against technological stress can be enhanced via cross-protection, which improves industrial efficiency concerning the survival of probiotics. However, the adaptive responses and cross-protection are strain-dependent and should be optimized case by case.