Food Lactic Acid Bacteria Research Articles

A review and prospects: Multi-omics and artificial intelligence-based approaches to understanding the effects of lactic acid bacteria and yeast interactions on fermented foods

There are numerous reports on the effect of co-culturing lactic acid bacteria (LAB) and yeast on the quality of fermented foods. The interactions between LAB and yeast affect the flavour, texture and even safety of fermented foods. Examining the specific mechanisms of these interactions becomes essential, but existing research methods are insufficient to meet the growing demands of scientific research. Multi-omics analysis provides more comprehensive information on LAB and yeast interactions than the widely used single-omics. Additionally, although the use of bioinformatics tools such as ModelSEED and CarveMe has simplified the construction of metabolic network models, there are still shortcomings in terms of accuracy and convenience. There is an urgent need to explore new methods to accelerate the study of microbial interaction mechanisms. This review summarizes the interaction between LAB and yeast in fermented foods, as well as the current research progress in revealing their interaction using multi-omics and bioinformatics tools. In the future, artificial intelligence will be a powerful aid in constructing metabolic models and obtaining models conveniently. Elucidation of interaction mechanisms at the spatial level will become more common, and more comprehensive research results will lead to further improvements in industrial practice.

Challenge of validation in whole-cell spike-in amplicon sequencing to comprehensively quantify food lactic acid bacteriota.

Lactic acid bacteria (LAB) shape diverse communities in fermented foods. Developing comprehensive quantification methods for community structure will revolutionize our understanding of food LAB microbiome. For this purpose, 16S rRNA gene amplicon-based quantification, using spiked exogenous bacterial cells as an internal standard, shows potential for comprehensiveness and accuracy. We validated cell spike-in amplicon sequencing for quantifying LAB communities in food. Low efficiency of LAB DNA extraction underscores the importance of compensating for DNA loss by spiking internal standard cells. Quantitative equations generated using 15 selected LAB mock species showed positive relationships between the ratio of MiSeq read counts and the expected 16S rRNA gene copy numbers, with coefficients of determination (R2) ≥ 0.6823. The fold differences between observed and expected 16S copy numbers were within the range of one-third to three-fold. Our validation highlights that accurate preparation of the LAB mock community is crucial for cell spike-in amplicon sequencing accuracy.

Selective influence of garlic as a key ingredient in kimchi on lactic acid bacteria in a fermentation model system

Garlic is an essential ingredient added to kimchi, a fermented vegetable, in small amounts owing to its sensory and antibacterial properties. This study aimed to elucidate the complex relationship between garlic and specific lactic acid bacteria (LAB) and the resulting metabolite changes in a controlled kimchi model system using nine strains as mixed and individual starters. The group without garlic using mixed starters showed the highest LAB growth activity, which influenced lactic acid production, pH, and titratable acidity. The group without garlic also showed differences in the composition of bacteria, such as Latilactobacillus sakei, Levilactobacillus brevis, unclassified Leuconostoc, and Weissella koreensis, during the fermentation period. In addition, the altering patterns of metabolites in the group without garlic during fermentation differed from those in the group with garlic. In addition, the metabolic profile of L. brevis group was mostly different from that of the other strains in the controlled model kimchi system using individual starters, suggesting that changes in LAB composition by garlic could subsequently affect metabolites during fermentation. This study provides valuable insights into the complex interactions among food ingredients, LAB succession, and metabolite production during fermentation.

Potential mechanism of improved cryotolerance of Pediococcus pentosaceus YT2 by cold acclimation based on TMT quantitative proteomics analysis

Lactic acid bacteria (LAB) are used in fermented foods to overcome the shortcomings of traditional fermentation methods, such as long cycles and poor safety. However, the application of LAB in low-temperature foods is limited by their growth temperature. This study aimed to quantitatively compare the proteins of the YT2 strain acclimated at 37, 28, 20, 15, 8, and 4 °C (YT-4) and that grown at 37 °C (YT-37) using tandem mass tag (TMT) proteomics and bioinformatics analysis to elucidate the potential mechanism of cryotolerance of P. pentosaceus YT2. Altogether, 1416 quantitative proteins were identified, of which 747 were differentially abundant between the YT-4 and YT-37 strains. Functional enrichment analysis showed that the upregulated proteins were mainly involved in nucleotide transport, metabolism, translation, ribosomal structure and biogenesis, transcription, replication, recombination, and repair, while the downregulated proteins were involved in lipid, amino, and carbohydrate transport and metabolism. These results were validated for eight upregulated and five downregulated proteins using parallel reaction monitoring (PRM). Our study analyzed the potential mechanism underlying the improved cryotolerance of P. pentosaceus YT2 at 4 °C, which may enable the utilization of LAB in low-temperature applications.

Enterocin AS‐48 inhibits the growth of – and biofilm formation by – lactic acid bacteria responsible for the accumulation of biogenic amines in cheese

SummaryCheese is a fermented food in which toxic concentrations of biogenic amines (BAs) may accumulate, mainly as a result of the metabolism of certain lactic acid bacteria (LAB); the formation of these compounds needs to be limited. This work reports the antimicrobial potential of bacteriocin AS‐48 against the LAB largely responsible for the accumulation of the BA histamine, tyramine and putrescine in cheese. Most of the 50 analysed BA‐producing LAB strains were sensitive to AS‐48. The bacteriocin also prevented biofilm formation of 92% of the BA‐producing strains tested. This result is of great technological importance since, in cheese production, biofilms are an important source of contamination by BA‐producing LAB. This study supports the potential use of AS‐48 as a biopreservative for controlling BA‐producing LAB in fermented food.

Transcriptome analysis reveals the mechanism underlying the tetracycline resistance of Lactiplantibacillusplantarum FZJTZ19M1 and FZJTZ29M8

Lactiplantibacillusplantarum is a species of lactic acid bacteria (LAB) commonly used in food. However, before it is used in food, the safety evaluation of antibiotic resistance must be carried out. Our study found that L.plantarum FZJTZ19M1 and FZJTZ29M8 had a high tetracycline resistance phenotype, but they did not contain any known tetracycline resistance genes. To investigate the tetracycline resistance mechanism of these two strains, we used transcriptome technology to explore the differentially expressed genes (DEG) produced by these two strains after tetracycline induction. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and protein-protein interaction (PPI) network analysis were used to reveal the important functional genes. Transcriptome results showed that 234 and 176 DEG were identified in L.plantarum FZJTZ19M1 and FZJTZ29M8, respectively. The results of GO, KEGG enrichment analysis, and PPI network analysis suggested that the resistance of L.plantarum FZJTZ19M1 to tetracycline might be caused by regulating amino acid metabolism and reducing the metabolism of fatty acids, biotin, and other substances. L.plantarum FZJTZ29M8 may increase resistance to tetracycline mainly by using (ATP-binding cassette) ABC transporters to excrete tetracycline from the body and reducing its cellular metabolism. This study revealed the tetracycline resistance mechanism of two L.plantarum strains at the transcriptional level and provided the theoretical reference for the safe application of this kind of LAB in food.

Transcriptome analysis reveals the tetracycline resistance mechanism of Lacticaseibacillus rhamnosus FXJWS19L2 and Lacticaseibacillus paracasei FQHXN23L6

Lacticaseibacillus rhamnosus and Lacticaseibacillus paracasei are widely used and regularly consumed probiotics. However, before they are used in food, safety evaluation of antibiotic resistance should be performed to assess the risk of transferring resistance genes. Our study found that L. rhamnosus FXJWS19L2 and L. paracasei FQHXN23L6 exhibited a high tetracycline resistance phenotype but did not contain any known tetracycline resistance genes in their genomes. To investigate the molecular mechanisms underlying tetracycline resistance in these two strains, we performed a transcriptomic analysis combined with gene overexpression techniques to explore potential resistance genes and validate their functions. The transcriptome analysis identified 963 and 372 differentially expressed genes (DEGs) in L. rhamnosus FXJWS19L2 and L. paracasei FQHXN23L6, respectively, after tetracycline induction. The DEGs in these two strains were mainly involved in ribosomal protein synthesis, ABC transporters, and the metabolism of many substances. Moreover, the overexpression of the most significantly up-regulated gene (yjcA), which encodes an ABC transporter, improved the resistance of bacteria to tetracycline. This study reveals the resistance mechanism of these two strains to tetracycline and provides a theoretical reference for the safe application of this type of lactic acid bacteria in food.

Avanços da aplicação de bactérias ácido láticas com funções probióticas na produção de fermentados láticos: uma revisão

Os alimentos com alegações funcionais têm ganhado destaque em virtude dos benefícios à saúde associados ao seu consumo. Produtos lácteos em sua maioria, são oriundos de fermentação por bactérias ácido-láticas (BAL). Esse grupo de microrganismos possui um grande papel no que diz respeito à fermentação de produtos alimentícios. Existem no mercado várias cepas, que são utilizadas na fabricação de produtos lácteos. Além da caracterização sensorial, é conhecido que algumas cepas de BAL apresentam funções probióticas. Frente a isso, este trabalho objetivou verificar os principais gêneros de BAL utilizados na produção de fermentados lácteos e sua funcionalidade probiótica. A partir da revisão bibliográfica no presente trabalho, foi possível evidenciar as contribuições que a inserção de BAL probióticas na alimentação humana pode agregar à saúde, assim como as espécies já autorizadas pela Agência Nacional de Vigilância Sanitária (ANVISA) na produção de alimentos e as que estão em processo de autorização/avaliação.

Strategies for the Development of Bioprotective Cultures in Food Preservation.

Consumers worldwide are increasingly demanding food with fewer ingredients, preferably without chemical additives. The trend called "Clean Label" has stimulated the development and commercialization of new types of bioprotective bacterial cultures. These bacteria are not considered new, and several cultures have been available on the market. Additionally, new bioprotective bacteria are being identified to service the clean label trend, extend the shelf life, and, mainly, improve the food safety of food. In this context, the lactic acid bacteria (LAB) have been extensively prospected as a bioprotective culture, as they have a long history in food production and their antimicrobial activity against spoilage and pathogenic microorganisms is well established. However, to make LAB cultures available in the market is not that easy, the strains should be characterized phenotypically and genotypically, and studies of safety and technological application are necessary to validate their bioprotection performance. Thus, this review presents information on the bioprotection mechanisms developed by LAB in foods and describes the main strategies used to identify and characterize bioprotective LAB with potential application in the food industry.

Comparison of Real-Time PCR and Droplet Digital PCR for the Quantitative Detection of Lactiplantibacillus plantarum subsp. plantarum

Droplet digital polymerase chain reaction (ddPCR) is one of the newest and most promising tools providing absolute quantification of target DNA molecules. Despite its emerging applications in microorganisms, few studies reported its use for detecting lactic acid bacteria. This study evaluated the applicability of a ddPCR assay targeting molecular genes obtained from in silico analysis for detecting Lactiplantibacillus plantarum subsp. plantarum, a bacterium mainly used as a starter or responsible for fermentation in food. The performance characteristics of a ddPCR were compared to those of a quantitative real-time PCR (qPCR). To compare the linearity and sensitivity of a qPCR and ddPCR, the calibration curve for a qPCR and the regression curve for a ddPCR were obtained using genomic DNA [102–108 colony-forming units (CFU)/mL] extracted from a pure culture and spiked food sample. Both the qPCR and ddPCR assays exhibited good linearity with a high coefficient of determination in the pure culture and spiked food sample (R2 ≥ 0.996). The ddPCR showed a 10-fold lower limit of detection, suggesting that a ddPCR is more sensitive than a qPCR. However, a ddPCR has limitations in the absolute quantitation of high bacterial concentrations (>106 CFU/mL). In conclusion, a ddPCR can be a reliable method for detecting and quantifying lactic acid bacteria in food.

Functional Characteristics of Kombucha Fermented with Lactic Acid Bacteria, Yeast, and Acetic Acid Bacteria Derived from Korea Traditional Foods

In this study, to determine the importance of lactic acid bacteria (LAB) in Kombucha fermentation, biological functions, such as organic acid production and anti-inflammatory and antibacterial activities, of Kombucha, with or without LAB inoculation, were evaluated. Lactobacillus paracasei DK215, Saccharomyces cerevisiae C3, and Acetobacter pasteurianus P2 were selected as the inoculants. Organic acids were measured every 3 days from the end of fermentation using HPLC; the organic acid content of LAB-inoculated Kombucha was relatively high. Samples with or without LAB inoculation showed high antibacterial activity against Escherichia coli. The MTT assay results indicated no significant difference in concentration difference and cell death. In the NO production test, compared with the uninoculated Kombucha sample, the LAB-inoculated Kombucha sample exhibited a value similar to that of the group without LPS treatment. The levels of cytokine (IL-1α, IL-6, TNF-α) production were significantly lower than those of the LPS(+) group, indicating the anti-inflammatory activity potential of the Kombucha sample. This improvement in the biological function of the LAB-inoculated Kombucha further verifies the value of LAB in the fermented food and beverage industry.

Antifungal Preservation of Food by Lactic Acid Bacteria.

Fungal growth and consequent mycotoxin release in food and feed threatens human health, which might even, in acute cases, lead to death. Control and prevention of foodborne poisoning is a major task of public health that will be faced in the 21st century. Nowadays, consumers increasingly demand healthier and more natural food with minimal use of chemical preservatives, whose negative effects on human health are well known. Biopreservation is among the safest and most reliable methods for inhibiting fungi in food. Lactic acid bacteria (LAB) are of great interest as biological additives in food owing to their Generally Recognized as Safe (GRAS) classification and probiotic properties. LAB produce bioactive compounds such as reuterin, cyclic peptides, fatty acids, etc., with antifungal properties. This review highlights the great potential of LAB as biopreservatives by summarizing various reported antifungal activities/metabolites of LAB against fungal growth into foods. In the end, it provides profound insight into the possibilities and different factors to be considered in the application of LAB in different foods as well as enhancing their efficiency in biodetoxification and biopreservative activities.

Potential biotherapeutic properties of lactic acid bacteria in foods

Today, the use of microorganisms to produce substances that can be consumable, used as a food ingredient and have a positive effect on consumer health is attracting attention and studies in this field are increasing. Besides, the therapeutic products produced by lactic acid bacteria (LAB) can be used in the food and pharmaceutical industry to create desirable characteristics of foods. In addition to the positive effects of LAB, probiotics and synbiotics have been known for many years, many studies examining postbiotics and paraprobiotics have attracted attention in recent years. The therapeutic products obtained from different LAB may have different properties and should be investigated widely. In this paper, the biotherapeutic substances produced by LAB and their effects on health are summarized.

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.

Distribution and Diversity of Nisin Producing LAB in Fermented Food

An attempt was made, to characterize natural antibiotics or lantibiotics from unconventional sources and its antibacterial spectrum against food borne pathogens and drug resistant bacteria. Six different traditional fermented foods i.e., fermented fish, fermented soybeans, Soibum (fermented bamboo shoots), milk, idly and dosa batter were used for the isolation of bacteriocin producing Lactic acid bacteria (LAB). Among all bacterial cultures isolated from the various sources, 129 cultures have found to produce antimicrobial compounds. Nisin specific reporter bacteria was utilized as biosensor to identify the Nisin like bacteriocin, where 10 cultures found to be positive Nisin producer. Identified Nisin like bacteriocin was partially concentrated by using ammonium sulphate followed by butanol extraction. Minimum inhibitory concentration (MIC) was analyzed against food borne pathogen and drug resistant bacteria. MIC of partially purified Nisin (pp-Nisin) of all the LAB isolates against food-borne pathogens are ranged between 0.5 and 92µg/ml respected to various Gram-positive bacteria. Similarly, the drug resistant bacteria were also inhibited by pp-Nisin (MIC ranged between 15 and 175µg/ml). All samples of ppnisin exhibited auto induction ability. Taxonomic identification of the nisin producers was done by whole genome sequencing which reveals that cultures belongs to Lactococcus lactis ssp. lactis. Also it was found that Lactococcus lactis ssp. lactis C2d and Lactococcus lactis ssp. lactis SP2C4 harbor nisA gene and Lactococcus lactis ssp. lactis FS2 (L. lactis FS2) harbor nisQ gene. The finding of this study highlights the first case of L. lactis FS2 isolated from fermented fish harbor nisQ gene. Antibacterial activity of pp-Nisin against drug resistant LAB is also reported.

Conjugal Transfer of Antibiotic Resistances in Lactobacillus spp.

Lactic acid bacteria (LAB) area heterogeneous group of bacteria which are Gram-positive, facultative anaerobes and non-motile, non-spore forming, with varied shapes from cocci to coccobacilli and bacilli. Lactobacillus is the largest and most widely used bacterial species amongst LAB in fermented foods and beverages. The genus is a common member of human gut microbiome. Several species are known to provide benefits to the human gut via synergistic interactions with the gut microbiome and their ability to survive the gut environment. This ability to confer positive health effects provide them a status of generally recognized as safe (GRAS) microorganisms. Due to their various beneficial characteristics, other factors such as their resistance acquisition were overlooked. Overuse of antibiotics has made certain bacteria develop resistance against these drugs. Antibiotic resistance was found to be acquired mainly through conjugation which is a type of lateral gene transfer. Several in vitro methods of conjugation have been discussed previously depending on their success to transfer resistance. In this review, we have addressed methods that are employed to study the transfer of resistance genes using the conjugation phenomenon in lactobacilli.

저장기간에 따른 다양한 식품 내 유산균의 동정 및 유산균 수 변화

According to the National Health and Nutrition Examination Survey (KNHANES), the eating habit patterns and perspectives of consumers change according to dietary life changes. Consumers are becoming increasingly interested in healthy and functional foods. The lactic acid bacteria (LAB) and probiotics have health-promoting functions and can facilitate the growth of useful bacteria, inhibit harmful bacteria, and promote smooth bowel movements. This study compared the contents of LAB in various foods, including biscuit, sand, and chocolate, according to the storage period of LAB-containing products and analyzed the predominant LAB at the end of storage. Upon examining the changes in the viability of lactic acid bacteria over a storage period of 7 months, we found that cell viability was maintained at 5.20—9.04 Log CFU/g on MRS agar and 5.60—9.18 Log CFU/g on BCP agar. The results of cross-testing by a certified food safety agency by the MFDS, demonstrated that cell viability was maintained at 5.65—8.34 Log CFU/g; additionally, cross-validation comparison results showed a similarity of 76.0%—100%. This indicated high accuracy of results and maintenance of the constant viability of lactic acid bacteria. The detected lactic acid bacteria in various foods were identified as Lactiplantibacillus (96—100%), Weissella confusa (99%), and Streptococcus thermophiles (99%). The expressed content of LAB on the outer packaging paper of the products was suitable for determining LAB content.

Antimicrobial Potential of Food Lactic Acid Bacteria: Bioactive Peptide Decrypting from Caseins and Bacteriocin Production.

Lactic acid bacteria (LAB) potential in the food industry and in the biotechnological sector is a well-established interest. LAB potential in counteracting especially food-borne infections has received growing attention, but despite being a road full of promises is yet poorly explored. Furthermore, the ability of LAB to produce antimicrobial compounds, both by ribosomal synthesis and by decrypting them from proteins, is of high value when considering the growing impact of multidrug resistant strains. The antimicrobial potential of 14 food-derived lactic acid bacteria strains has been investigated in this study. Among them, four strains were able to counteract Listeria monocytogenes growth: Lactococcus lactis SN12 and L. lactis SN17 by high lactic acid production, whereas L. lactis 41FLL3 and Lactobacillus sakei I151 by Nisin Z and Sakacin P production, respectively. Strains Lactococcus lactis MG1363, Lactobacillus rhamnosus 17D10 and Lactobacillus helveticus 4D5 were tested and selected for their potential attitude to hydrolyze caseins. All the strains were able to release bioactive peptides with already known antimicrobial, antihypertensive and opioid activities. These features render these strains or their bioactive molecules suitable for use in food as biocontrol agents, or as nutraceutical supplements to treat mild disorders such as moderate hypertension and children insomnia. These results highlight once again that LAB potential in ensuring food safety, food nutraceutical value and ultimately in favoring human health is still underexplored and underexploited.

Inactivation of Foodborne Pathogens by Lactic Acid Bacteria

The problems caused by foodborne pathogens are not only a concern to the food industry but also with regard to global public health. Over the years, fermentation technology has proved to be one of the cheapest and safest methods for inactivating and controlling pathogenic microorganisms in food. Scientific evidence shows that lactic acid bacteria fermentation exerts significant antimicrobial effect against pathogenic bacteria and viruses. Lactic acid bacteria metabolites such as organic acids, bacteriocins and hydrogen peroxides have adverse effects on foodborne pathogens which lead to their inhibition. These compounds do not only cause physical injuries, but also have significant effects on the pathogens' gene expression. Furthermore, the presence of lactic acid bacteria in food provides nutritional competition among foodborne pathogens, and all these factors together suppress their growth. This study reviews our current knowledge of the antimicrobial abilities of lactic acid bacteria, their molecular mechanisms, and their application for inactivating foodborne pathogens.

Evaluation of Petrifilm Lactic Acid Bacteria Plates for Counting Lactic Acid Bacteria in Food

Although lactic acid bacteria (LAB) are used widely as starter cultures in the production of fermented foods, they are also responsible for food decay and deterioration. The undesirable growth of LAB in food causes spoilage, discoloration, and slime formation. Because of these adverse effects, food companies test for the presence of LAB in production areas and processed foods and consistently monitor the behavior of these bacteria. The 3M Petrifilm LAB Count Plates have recently been launched as a time-saving and simple-to-use plate designed for detecting and quantifying LAB. This study compares the abilities of Petrifilm LAB Count Plates and the de Man Rogosa Sharpe (MRS) agar medium to determine the LAB count in a variety of foods and swab samples collected from a food production area. Bacterial strains isolated from Petrifilm LAB Count Plates were identified by 16S rDNA sequence analysis to confirm the specificity of these plates for LAB. The results showed no significant difference in bacterial counts measured by using Petrifilm LAB Count Plates and MRS medium. Furthermore, all colonies growing on Petrifilm LAB Count Plates were confirmed to be LAB, while yeast colonies also formed in MRS medium. Petrifilm LAB Count Plates eliminated the plate preparation and plate inoculation steps, and the cultures could be started as soon as a diluted food sample was available. Food companies are required to establish quality controls and perform tests to check the quality of food products; the use of Petrifilm LAB Count Plates can simplify this testing process for food companies.