Effects Of Lactic Acid Bacteria Research Articles

Synergistic Antibacterial Effect of Lactic Acid Bacteria and Baicalin Against Staphylococcus aureus In Vitro and In Vivo.

Pathogenic bacteria such as Staphylococcus aureus (S. aureus) are the principal cause of cow mastitis, which primarily impacts milk yield and results in significant financial losses for the animal husbandry industry. Lactic acid bacteria-cell-free supernatant (LAB-CFS) and baicalin (BAI) both have a number of biological effects, including decreasing inflammation. The combined use of LAB-CFS and BAI does not appear to have been used toprotective against mastitis, however, and the underlying mechanisms are yet unknown. In this study, in vitro activity of LAB-CFS and BAI alone and in combination was determined (checkerboard experiments, time-kill curves, and flow cytometry to investigate membrane permeability) and examined the protective effects of LAB-CFS and BAI on S. aureus-induced mastitis in mice and the impact of NF-κB signaling pathways on the emergence of mastitis. We discovered that when LAB-CFS and BAI were used together, S. aureus was more effectively treated than when LAB-CFS and BAI were used separately. Flow cytometry demonstrated that LAB-CFS and BAI work together to kill bacteria. In vivo, the usage of LAB-CFS and BAI decreased the activity of myeloperoxidase, as well as IL-6, IL-1β, and TNF-α secretion and the levels of TLR2 and p65 (NF-κB) expression. These findings suggested that LAB-CFS and BAI had a preventive effect against mastitis brought on by S. aureus. Therefore, the NF-κB signaling pathway is thought to be the likely mechanism through which LAB-CFS and BAI reduced S. aureus-induced inflammation in the mammary of cows. For the treatment of cow mastitis, LAB-CFS and BAI are likely to replace antibiotics.

The Therapeutic Effects of Lactic Acid Bacteria Isolated from Spotted Hyena on Dextran Sulfate Sodium-Induced Ulcerative Colitis in Mice.

Inflammatory bowel disease (IBD) is a chronic condition characterized by recurrent episodes and an unclear etiology. Given the limitations of current therapeutic options, which include suboptimal efficacy and significant side effects, there is a pressing need to explore novel treatments. Probiotics derived from diverse species have been identified as a promising approach for managing IBD, owing to their anti-inflammatory properties and their ability to regulate gut flora, among other beneficial effects. In this study, three strains of lactic acid bacteria (LAB) were isolated from the feces of the scavenger spotted hyena (Crocuta crocuta), a scavenging mammal. Based on their capability to survive within and adhere to the gastrointestinal tract, along with their profile of antibiotic resistance, a high-quality strain of Lactobacillus acidophilus (LA) was selected and demonstrated to be safe for mice. Subsequently, the therapeutic efficacy of LA was evaluated using a dextran sulfate sodium (DSS)-induced model of ulcerative colitis in mice. The results indicated that LA restored the disease activity index and improved histopathological lesions in the model group. It also reduced inflammation and oxidative stress and significantly restored the expression of mucins and intestinal tight junction (TJ) proteins (ZO-1, Occludin). Furthermore, LA corrected the DSS-induced disruption of the intestinal flora, leading to a significant decrease in the prevalence of potentially harmful bacterial genera, such as Bacteroides, and an increase in beneficial bacterial genera, including Lactobacillus. In conclusion, Lactobacillus acidophilus LA1, isolated from spotted hyena feces, has potential as a functional supplement for alleviating symptoms of IBD and regulating intestinal flora.

Effects of lactic acid bacteria and cellulase additives on the fermentation quality, antioxidant activity, and metabolic profile of oat silage

Oats (Avena sativa L.) are rich in nutrients and bioactive compounds, serving as a roughage source for ruminants. This study investigated the impact of lactic acid bacteria (LAB), cellulase (M), and their combinations (LM) on the fermentation quality and metabolic compounds of oat silage. Results demonstrated that all additive treatments significantly increased lactic acid content compared to the control group (P < 0.05), with the lactic acid bacteria treatment group exhibiting the lowest pH value (P < 0.05). Analysis of antioxidant activity and metabolites in oat silage over 60 days revealed 374 differential metabolites with 113 up-regulated and 261 down-regulated, and all treatment groups showing higher antioxidant activity than raw oat materials (P < 0.05). Although no significant differences in antioxidant activity were observed among the various treatment groups in this experiment, notable changes in metabolic pathways were identified. Furthermore, two metabolites (carboxylic acids and derivatives and benzene and substituted derivatives) were identified through non-targeted metabolomics technology, both of which are strongly associated with the antioxidant activity of oat silage. This finding provides a theoretical basis for the efficient use of oat silage in animal husbandry.Graphical abstract

Effect of Lactic Acid bacteria as Feed Additive on Growth Performance, Intestinal Flora and Serum Parameters in Broilers

Effect of Lactic Acid bacteria as Feed Additive on Growth Performance, Intestinal Flora and Serum Parameters in Broilers

Biotransformation of insect processing residues: Production of lactic acid bacterial biomass and associated partial removal of proteins from chitin

Processing of edible insects typically involves fractionating into high-value food ingredients, which results in by-products containing chitin and insoluble proteins. This study examined the effectiveness of lactic acid bacteria (LAB) in removing proteins from chitin in insect processing residues. Lesser mealworm processing residues were biologically treated for 48 and 120 h using LAB strains without added carbon sources. Results showed partial deproteinization, up to 29 % with Levilactobacillus brevis after 120 h. Most LAB grew up to 2 log10 colony-forming units/mL in the first 48 h. Confocal microscopy and Fourier-transform infrared spectra indicated that some protein remained attached to chitin. The molecular weight of solubilized proteins was affected by strain and time of incubation, with antioxidant activity increasing significantly after 120 h with Lacticaseibacillus paracasei. The biological treatment of insect processing streams can be a sustainable approach to producing high amounts of LAB biomass with subsequent protein solubilization and chitin release.

PENGARUH LAMA WAKTU FERMENTASI DAUN KELOR (Moringa oleifera) DENGAN BAKTERI ASAM LAKTAT TERHADAP KONSENTRASI ASAM AMINO

Moringa (Moringa oleifera) is a nutrient-densed food that can be used as a food source and possess pharmacological properties. Fermented Moringa has a better amino acid profiles and potentially has a greater digestibility. Nevertheless, the effect of lactic acid bacteria as fermentation culture on Moringa’s amino acid profiles is warrant for investigation. The purpose of this study was to determine the effect of the Moringa’s fermentation with lactic acid bacteria on its nutritional value, especially amino acid. In this study, Moringa leaves were fermented with lactic acid bacteria for 0, 24, and 48 hours. Amino acid concentrations with fermentation 0, 24, and 48 hours respectively were 1007.94 mg/kg, 1304.13 mg/kg, and 521.12 mg/kg, where the highest concentration of amino acids was in Moringa leaves which were fermented for 24 hours. The concentrations of various amino acids in Moringa leaves were measured by High Performance Liquid Chromatography. The best treatment was 24 hours of fermentation, where the total amino acid (TAA) was 1304.13 mg/kg.

Effects of Lactic Acid Bacteria on Reducing the Formation of Biogenic Amines and Improving the Formation of Antioxidant Compounds in Traditional African Sourdough Flatbread Fermentation.

This study investigated the safety and functionality of traditional African sourdough flatbread (kisra), based on the content of biogenic amines (BAs) and antioxidant compounds and their improvement using lactic acid bacteria (LAB) species. The primary BAs detected in naturally fermented kisra were tyramine, histamine, putrescine, and cadaverine, with putrescine being the most abundant after baking. In vitro BA production of microorganisms isolated from kisra sourdough revealed that the Enterococcus genus contributed to tyramine accumulation, whereas presumptive yeasts may contribute to putrescine and cadaverine accumulation. The use of LAB species, including Lactiplantibacillus plantarum, Limosilactobacillus fermentum, Levilactobacillus brevis, and Weissella cibaria, significantly reduced putrescine content to less than about 23% of that of naturally fermented kisra, and eliminated tyramine, histamine, and cadaverine formation. Meanwhile, DPPH scavenging activity, total polyphenolic content, and tannin content in naturally fermented kisra were 85.16%, 1386.50 µg/g, and 33.16 µg/g, respectively. The use of LAB species did not affect the DPPH scavenging activity or tannin content but significantly increased the total phenolic content by up to 20% compared to naturally fermented kisra. Therefore, fermentation with LAB starter cultures might be a promising approach to improve the safety related to BAs as well as the functionality of kisra bread.

Lactococcus lactis subsp. cremoris YRC3780 modifies function of mesenteric lymph node dendritic cells to modulate the balance of T cell differentiation inducing regulatory T cells.

The intestinal immune system plays a pivotal role in the induction of immune responses against food. In the case of T cell response, dendritic cells (DCs) are especially important. However, the regulation of immune responses to food by intestinal DCs has been poorly described. In this study, we analyzed the effect of Lactococcus lactis subsp. cremoris YRC3780, a lactic acid bacterial strain isolated from kefir, a traditional fermented milk product, on the immune responses induced by antigen presentation by intestinal DCs to T cells as well as the mechanism of action of these immunomodulatory effects. It has been shown that L. cremoris YRC3780 ameliorates the symptoms of pollinosis in both animal and human studies. CD11c+ cells from mesenteric lymph nodes (MLNs) of BALB/c mice were cultured as MLN DCs with L. cremoris YRC3780 and expression of genes inducing regulatory T cells (Tregs) was examined by qPCR. In addition, MLN DCs were cocultured with CD4+ T cells from DO11.10 transgenic mice expressing an ovalbumin (OVA)-specific TCR and the OVA antigen peptide and L. cremoris YRC3780. Induction of Tregs was examined by flow cytometry, gene expression was analyzed by DNA microarray and qPCR, and the production of cytokines was measured by ELISA. MLN DCs from TLR2-deficient mice and components of L. cremoris YRC3780 were used to examine the recognition of YRC3780 by MLN DCs. L. cremoris YRC3780 enhanced the expression of genes involved in Treg induction in MLN DCs and induced Foxp3+CD4+T cells in an MLN DC and CD4+ T-cell co-culture system. The effect on MLN DCs was likely mediated by receptors other than TLR2. Together with microarray analyses of CD4+ T cell gene expression and cytokine ELISA, it was demonstrated that L. cremoris YRC3780 promoted the induction of Th1 and Tregs, and regulated the balance of Th1/Th2 and Treg/Th17 cells involving multiple genes via the antigen-presentation of MLN DCs. Our findings provide insights into the modulation of intestinal immune responses mediated by DCs and the antiallergic effects of lactic acid bacteria.

Physiological Effects of Lactic Acid Bacteria on Induced Non-Alcoholic Fatty Liver Disease in Male Laboratory Rats

Physiological Effects of Lactic Acid Bacteria on Induced Non-Alcoholic Fatty Liver Disease in Male Laboratory Rats

Combined Effects of Lactic Acid Bacteria and Protease on the Fermentation Quality and Microbial Community during 50 Kg Soybean Meal Fermentation Simulating Actual Production Scale.

The improvement in the utilization rate and nutritional value of soybean meal (SBM) represents a significant challenge in the feed industry. This study conducted a 50 kg SBM fermentation based on the 300 g small-scale fermentation of SBM in early laboratory research, to explore the combined effects of lactic acid bacteria (LAB) and acid protease on fermentation quality, chemical composition, microbial population, and macromolecular protein degradation during fermentation and aerobic exposure of SBM in simulated actual production. The results demonstrated that the increase in crude protein content and reduction in crude fiber content were considerably more pronounced after fermentation for 30 days (d) and subsequent aerobic exposure, compared to 3 d. It is also noteworthy that the treated group exhibited a greater degree of macromolecular protein degradation relative to the control and 30 d of fermentation relative to 3 d. Furthermore, after 30 d of fermentation, adding LAB and protease significantly inhibited the growth of undesired microbes including coliform bacteria and aerobic bacteria. In the mixed group, the microbial diversity decreased significantly, and Firmicutes replaced Cyanobacteria for bacteria in both groups' fermentation.

Anti-fungal effects of lactic acid bacteria from pickles on the growth and sterigmatocystin production of Aspergillus versicolor

Sterigmatocystin (STC) is an emerging mycotoxin that poses a significant threat to the food security of cereal crops. To mitigate STC contamination in maize, this study employed selected lactic acid bacteria as biocontrol agents against Aspergillus versicolor, evaluating their biocontrol potential and analyzing the underlying mechanisms. Lactiplantibacillus plantarum HJ10, isolated from pickle, exhibited substantial in vitro antifungal activity and passed safety assessments, including antibiotic resistance and hemolysis tests. In vivo experiments demonstrated that L. plantarum HJ10 significantly reduced the contents of A. versicolor and STC in maize (both >84 %). The impact of heat, enzymes, alkali, and other treatments on the antifungal activity of cell-free supernatant (CFS) was investigated. Integrated ultra-high-performance liquid chromatography (UPLC) and gas chromatography–mass spectrometry (GC–MS) analysis revealed that lactic acid, acetic acid, and formic acid are the key substances responsible for the in vitro antifungal activity of L. plantarum HJ10. These metabolites induced mold apoptosis by disrupting cell wall structure, increasing cell membrane fluidity, reducing enzyme activities, and disrupting energy metabolism. However, in vivo antagonism by L. plantarum HJ10 primarily occurs through organic acid production and competition for growth space and nutrients. This study highlights the potential of L. plantarum HJ10 in reducing A. versicolor and STC contamination in maize.

Immune Boosting Effect of Limosilactobacillus Reuteri in Immunocompetent C57BL/6J Mice.

Probiotics are well-known to be directly or indirectly involved in the host immune system. In this study, we analyzed the immune-boosting effects of lactic acid bacteria, including Limosilactobacillus and Lactococcus, in immunocompetent C57BL/6J mice. Three different lactic acid bacteria strains were orally administered to C57BL/6J mice for 8 weeks. Then, liver, spleen, and whole blood were harvested after sacrificing the animals. There were no significant changes in whole-body weight, weight of organs, or complete blood cell count by oral administration of lactic acid bacteria. The frequencies of CD3+, CD4+, and CD8+ T cells were significantly increased in the Limosilactobacillus reuteri MG5462 group compared to control. The frequency of NK1.1+ cells was significantly increased in the Lactococcus lactis MG5474 group compared to control. On the other hand, splenocyte proliferations and natural killer cytotoxicity did not differ between groups. In addition, the MG5462 group had a significant increase in the production of TNF-α compared to the control, which is consistent with the upregulation of T cells in the MG5462 group. Therefore, Limosilactobacillus reuteri could be a functional food additive to boost immunity by positively affecting T cell populations.

Differences in the Ability of Lactic Acid Bacteria To Prevent Acute Alcohol-Induced Liver Injury via the Gut Microbiota-Bile Acid-Liver Axis.

Probiotics can regulate gut microbiota and protect against acute alcohol-induced liver injury through the gut-liver axis. However, efficacy is strain-dependent, and their mechanism remains unclear. This study investigated the effect of lactic acid bacteria (LAB), including Lacticaseibacillus paracasei E10 (E10), Lactiplantibacillus plantarum M (M), Lacticaseibacillus rhamnosus LGG (LGG), Lacticaseibacillus paracasei JN-1 (JN-1), and Lacticaseibacillus paracasei JN-8 (JN-8), on the prevention of acute alcoholic liver injury in mice. We found that LAB pretreatment reduced serum alanine transaminase (ALT) and aspartate transaminase (AST) and reduced hepatic total cholesterol (TC) and triglyceride (TG). JN-8 pretreatment exhibited superior efficacy in improving hepatic antioxidation. LGG and JN-8 pretreatment significantly attenuated hepatic and colonic inflammation by decreasing the expression of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) and increasing the expression of interleukin 10 (IL-10). JN-1 and JN-8 pretreatments have better preventive effects than other LAB pretreatment on intestinal barrier dysfunction. In addition, the LAB pretreatment improved gut microbial dysbiosis and bile acid (BA) metabolic abnormality. All of the strains were confirmed to have bile salt deconjugation capacities in vitro, where M and JN-8 displayed higher activities. This study provides new insights into the prevention and mechanism of LAB strains in preventing acute alcoholic liver injury.

Earthworms and lactic acid bacteria (LAB) cooperate to promote the biodegradation of tetracycline residues in livestock manure

Tetracycline is an antibiotic with extensive veterinary use in the livestock industry. However, their widespread application poses risks to soil health as residue in livestock feces, and their removal is crucial for sustainable soil-ecosystem development. Physical and chemical approaches to extract tetracycline may have adverse effects on soil ecosystems, but no studies have thus far examined the potential for biological methods, such as collective degradation action of soil fauna. Thus, this study aimed to investigate the synergistic effects of lactic acid bacteria (LAB) and earthworms (Eisenia fetida) on biodegradation of tetracycline residues in sheep manure. We assessed earthworm biomass, tetracycline residue, and bacterial communities in both earthworm intestines and vermicompost. Earthworm biomass and tetracycline degradation efficiency increased significantly with LAB addition, with a degradation rate of up to 80.16%. This increase may be attributable to LAB acting as electron donors to spur tetracycline degradation. Additionally, we noted that tetracycline presence significantly influenced bacterial communities in earthworm intestines and vermicompost, elevating the abundance of potential pathogenic bacteria (e.g., Flavobacterium, Gammaproteobacteria, and Enterobacteriaceae). This finding suggests that heightened environmental stress from antibiotics could actually facilitate the growth of less prevalent bacteria, including potential pathogens. In conclusion, our study provides evidence supporting the effectiveness of LAB and earthworms in degrading tetracycline residues. In particular, LAB appears to mitigate stress from tetracycline exposure in earthworms, thus increasing their vermicomposting efficacy. Our work has important implications for soil management, with the potential to enhance pollution clean-up rates while minimizing negative side-effects to soil microbial communities.

Effect of lactic acid bacterial starter KUB-G2 on grass silage quality and its microbial community performed using 140-ton plastic bag silos: a large-scale study

This study investigated the effectiveness of lactic acid bacteria (LAB) starters in 140 tons of signal grass silage. We compared a locally developed starter, a combination of Lactiplantibacillus plantarum KUB-SP1-3 and Pediococcus acidilactici KUB-M6 (KUB-G2) with a commercial starter. We monitored the chemical and microbiological properties of silage at ensiling (day 0) and after 21 days. The results indicated that KUB-G2 produced high-quality silage. There were no significant differences in total viable microbes, lactic acid, or propionic acid contents between the starters. However, the silage produced with KUB-G2 had a lower acetic acid content than that produced with the commercial starter. KUB-G2 also resulted in a narrower microbiome profile dominated by Pediococci whereas the control group displayed a broader range of bacterial taxa with colonization by Lactiplantibacillus and Lentilactobacillus. These findings suggested that KUB-G2, with its distinct microbial profile, is a suitable replacement for imported commercial starters in large-scale signal grass silage production.

Characterization and potential lipid-lowering effects of lactic acid bacteria isolated from cats.

This study aimed to study the characterization and the potential lipid-lowering effects of new isolated lactic acid bacteria from the feces of healthy adult cats. We collected 85 cat fecal samples, isolated, screening lactic acid bacteria strains from samples, and investigated their in vitro and in vivo biological properties. A total of 221 lactic acid bacteria strains were isolated from 85 cat fecal samples. Sixteen strains with calcium dissolution rings greater than 1 mm were identified and selected for further characterization. Three lactic acid bacteria strains, Lactobacillus plantarum L-27-2, Pediococcus lactis L-14-1, and Enterococcus faecium, were identified as showing the most promising rates of cholesterol degradation (greater than 20%) and bacteriostatic radius (over 15 mm). These three strains exhibited robust growth and adherence to epithelial cells, along with adaptability to low pH (greater than 70%) and high bile salt conditions (greater than 60%), and remarkable cholesterol degradation and anti-pathogen activity. Sixteen mice were fed a high-fat diet (HFD) from 4 to 8 weeks of age, while a control group of the same size received a normal diet (ND). At 8 weeks of age, serum, feces and adipose tissue were collected. The results showed that, compared with mice fed an HFD diet alone, all mice fed an HFD diet plus lactic acid bacteria could decrease weight gain. P < 0.05 and the pathological changes of adipose tissue were alleviated. In addition, mice fed L-14-1 and F203 showed abdominal fat accumulation decreased (P < 0.05). Mice fed L-27-2 showed serum and liver triglyceride (TG) decreased (P < 0.05) and mice fed F203 showed serum high density lipoprotein cholesterol (HDL-C) increased (P < 0.01). mice fed L-27-2 and L-14-1 showed inflammatory cytokines (IL-6) was decreased (P < 0.01) Analysis of the fecal microbiota of mice fed these three lactic acid bacteria strains revealed alterations in the gut microbial community. There were common changes in intestinal microbes in mice fed these three lactic acid bacteria: (1) Bacteroides decreased; (2) Myxococcus increased; (3) Lachnoclostridium decreased. The microbes mentioned are all part of the core intestinal flora. This study provided three potential lactic acid bacteria for alleviating animal obesity and inflammation.

Effects of lactic acid bacteria exposed to extreme conditions on yoghurt quality

In this study, two bacterial strains used in the production of yoghurt were subjected to three distinct stress conditions (low pressure, infrared light, and low pressure + infrared light) and then used as starter cultures for yoghurt production. The obtained results revealed that the bacterial stress response mechanisms, especially those of bacteria exposed to low pressure, positively affected the physicochemical, textural, and microbiological quality during storage of yoghurts produced with these bacteria. In addition, it was found that prolonging the exposure time to stress conditions increased this effect even more. The samples subjected to low pressure for 2 hours had the shortest fermentation time among all samples, while the samples subjected to infrared light for 2 hours had the longest fermentation time. Yoghurts produced with bacteria subjected to low pressure conditions had more organic acids and aroma components and less syneresis during storage compared to other samples. Furthermore, it was determined that yoghurt samples produced with bacteria exposed to stress conditions had higher L* and a* values, lower b* values, improved textural values, and higher bacterial counts during the 7-day storage period compared to control samples.

Effects of Lactic Acid Bacteria on The Quality of Steamed Bread and Its Process Transformation

The starter culture of traditional steamed buns is composed of a variety of microorganisms, among which lactic acid bacteria are the main source of fermentation. The quality of the product is directly affected by the diversity and abundance of lactic acid bacteria. As a probiotic that plays an important role in many fields, lactic acid bacteria have an important impact on the quality of steamed buns. These effects include enhanced nutritional value, improved flavor, altered texture, extended shelf life, production of antioxidants, etc. The dough fermentation method in which lactic acid bacteria play a major role is called sourdough. It has better technological value than ordinary dough and is one of the research focuses of the food industry. This study explores the natural link between lactic acid bacteria and the flavor, texture, antioxidant activity, and nutritional value of steamed bun dough. At the same time, the effects of process improvement and the addition of new raw materials on the quality and nutritional properties of steamed buns fermented by lactic acid bacteria were explored.

The Health Regulatory Effect of Lactic Acid Bacteria on Human Body

Probiotics are a kind of active microorganisms that are beneficial to the host by colonizing in the human body and changing the composition of the flora in a certain part of the host. The organic acids, special enzymes and actinomycin’s produced by lactic acid bacteria (LAB) have special physiological functions. LAB can regulate the normal flora of gastrointestinal tract and maintain the microecological balance, so as to improve gastrointestinal function, increase food digestibility and biotiter, reduce serum cholesterol, control endotoxin, inhibit the growth of spoilage bacteria in intestinal tract, and improve body immunity. This paper studied the existence mode and influencing factors of probiotics and took LAB as an example to mainly describe the research progress of LAB in probiotics, discussed the mechanism of probiotics to maintain the ecological balance of intestinal flora, summarized the impact of probiotics on human body, and aimed at various problems and deficiencies faced by the probiotic industry at present. Some suggestions on the future research direction are put forward.

The Potential Teeth Bleaching and Halitosis Prevention Effects of Pediococcus inopinatus THK-30, a Kimchi-Derived Lactic Acid Bacterium: In Vitro Study.

Recent developments in addressing dental aesthetic concerns, encompassing issues like teeth discoloration and halitosis, underscore the demand for safer alternative solutions. This study aims to confirm the effects of lactic acid bacteria (LAB) from kimchi on artificial teeth bleaching and their potential impact in terms of preventing halitosis-related bacteria. To evaluate the antimicrobial effects against oral pathogens, disc diffusion tests and broth microdilution methods were used. Additionally, crystal violet analysis was performed to confirm the biofilm inhibition effect. The bleaching effects on stained artificial teeth were analyzed using the CIEDE2000 colorimetric method. Statistical analyses were performed using GraphPad Prism 9 with one-way and two-way ANOVA, with the significance level set at α < 0.05. The strain THK-30, isolated from kimchi, exhibited antibacterial activity against Streptococcus mutans, Porphyromonas gingivalis, and Fusobacterium nucleatum, and was identified as Pediococcus inopinatus. Moreover, THK-30 showed a synergistic antibacterial effect against Gram-negative oral pathogens with 8% sodium hexametaphosphate (SHMP). In the stained artificial teeth bleaching test and artificial teeth biofilm inhibition test, the cell-free supernatant of THK-30 displayed significant teeth bleaching effects and caused the inhibition of biofilm formation, both independently and in combination with SHMP 8%. This study has demonstrated the potential applicability of LAB in teeth discoloration and halitosis. These findings are poised to provide a foundation for the development of research pertaining to the control of oral bacteria.