Acetic Acid-producing Bacteria Research Articles

Anaerobic co-digestion of food waste and excess sludge by humus composites: Characteristics and microbial community structure

Volatile fatty acids (VFA) produced during the anaerobic co-digestion (Co-AD) an Manual removal of impurities such as bones, fish spines, napkins, etc., after collection at the food waste collection sited hydrolysis of food waste (FW) and excess sludge (ES) are important factors affecting the stability of the digestion and biogas production. This study aimed to use humus composites (HS) to mediate the Co-AD system of FW and ES, investigate their effects on VFA conversion, and analyze the microbial community structure using high-throughput sequencing technology to reveal the mechanism of action of HS in mediating the Co-AD system from a microbial perspective. The amount of HS was positively correlated with the accumulation of VFA produced by the hydrolysis of co-digested substrates, and in the Co-AD system with 5.00 g/L HS, the accumulation of VFA increased by approximately 1.1 times, whereas the pH and oxidation reduction potential of the system tended to be in the benign range, offering a favoring condition for enhancing the stability of the system. The biogas production increased by 46.3 % compared with that of the blank group. HS significantly increased the relative abundance values of Synergistota, a mutualistic symbiont with acetic acid-producing bacteria, and Proteobacteria, a mutualistic symbiont with methanogenic bacteria, thus promoting VFA conversion and strengthening the Co-AD efficacy of FW and ES. This study provides a simple and effective method to improve the Co-AD efficacy of FW and ES, as well as a new approach for the anaerobic resource treatment of other organic solid wastes.

Antibiotic Resistance in Acetic Acid Bacteria Originating from Vinegar.

Acetic acid bacteria (AAB) are major contributors to the production of fermented vinegar, offering various cultural, culinary, and health benefits. Although the residual unpasteurized AAB after vinegar production are not pathogens, these are necessary and require safety evaluations, including antibiotic resistance, before use as a starter. In this research, we investigated the antibiotic resistance profiles of 26 AAB strains, including various species of Komagataeibacter and Acetobacter, against 10 different antibiotics using the E-test method. All strains exhibited resistance to aztreonam and clindamycin. Komagataeibacter species demonstrated a 50% resistance rate to ciprofloxacin, analogous to Acetobacter species, but showed twice the resistance rates to chloramphenicol and erythromycin. Genomic analysis of K. saccharivorans CV1 identified intrinsic resistance mechanisms, such as multidrug efflux pumps, thereby enhancing our understanding of antibiotic resistance in acetic acid-producing bacteria. These findings enhance understanding of antibiotic resistance in AAB for food safety and new antimicrobial strategies, suggesting the need for standardized testing methods and molecular genetic study.

Microbial metabolite sodium butyrate enhances the anti-tumor efficacy of 5-fluorouracil against colorectal cancer by modulating PINK1/Parkin signaling and intestinal flora

Colorectal cancer (CRC) is a prevalent global health issue, with 5-fluorouracil (5-FU) being a commonly used chemotherapeutic agent for its treatment. However, the efficacy of 5-FU is often hindered by drug tolerance. Sodium butyrate (NaB), a derivative of intestinal flora, has demonstrated anti-cancer properties both in vitro and in vivo through pro-apoptotic effects and has shown promise in improving outcomes when used in conjunction with traditional chemotherapy agents. This study seeks to evaluate the impact and potential mechanisms of NaB in combination with 5-FU on CRC. We employed a comprehensive set of assays, including CCK-8, EdU staining, Hoechst 33258 staining, flow cytometry, ROS assay, MMP assay, immunofluorescence, and mitophagy assay, to detect the effect of NaB on the biological function of CRC cells in vitro. Western blotting and immunohistochemistry were used to verify the above experimental results. The xenograft tumor model was established to evaluate the in vivo anti-CRC activity of NaB. Subsequently, 16S rRNA gene sequencing was used to analyze the intestinal flora. The findings of our study demonstrate that sodium butyrate (NaB) exerts inhibitory effects on tumor cell proliferation and promotes tumor cell apoptosis in vitro, while also impeding tumor progression in vivo through the enhancement of the mitophagy pathway. Furthermore, the combined treatment of NaB and 5-fluorouracil (5-FU) yielded superior therapeutic outcomes compared to monotherapy with either agent. Moreover, this combination therapy resulted in the specific enrichment of Bacteroides, LigiLactobacillus, butyric acid-producing bacteria, and acetic acid-producing bacteria in the intestinal microbiota. The improvement in the intestinal microbiota contributed to enhanced therapeutic outcomes and reduced the adverse effects of 5-FU. Taken together, these findings indicate that NaB, a histone acetylation inhibitor synthesized through intestinal flora fermentation, has the potential to significantly enhance the therapeutic efficacy of 5-FU in CRC treatment and improve the prognosis of CRC patients.

Isolation and characterization of Indole Acetic Acid-producing bacteria isolated from rhizospheric soil of paddy rice

Plant growth-promoting rhizobacteria have immense potential to be used as an environmentally friendly replacement for chemical fertilizers and pesticides, through the production of various plant growth-promoting substances. The objectives of this study were the isolation, characterization, and identification of indole acetic acid-producing bacteria from the rhizospheric soil of paddy rice. Out of all screened isolates, isolate 1.4 was the highest IAA producer with 29.76 µg/mL. The culture medium conditions to obtain the highest IAA production were optimized as follows: the culture temperature was 30°C, the incubation time was three days, and the pH was 7.0. The 16S rRNA gene sequence showed that isolate 1.4 has been genetically identified as Bacillus altitudinis, and it can potentially be used as an efficient biofertilizer.

Machine learning approach for microbial growth kinetics analysis of acetic acid-producing bacteria isolated from organic waste

This study proposes novel hybrid methodology that combines machine learning (ML) techniques with experimental strategies to analyse microbial growth-kinetics of acetic acid-producing bacteria isolated from fruit waste. This work employs ML algorithms to create different models such as multivariate linear regression (MLR), partial least square regression (PLSR), Kernel ridge regression (KRR), support vector regression (SVR), Gradient boosting regression (GBR) that captures time-dependent patterns of bacterial growth dynamics. Experiments for microbial growth kinetic analysis were conducted on best isolate of acid producing bacteria with different glucose concentrations (1–5 %) at predefined operating conditions. It is found significant growth rate (µ) was obtained at 4 % and 5 % concentration of glucose from experimental work. 0.0588 h−1 and 0.0571 h−1 are the specific growth rate obtained at 4 % and 5 % glucose concentration respectively. Proposed ML models employed to predict growth rate kinetics theoretically at varied glucose concentrations. Comparative results indicate that GBR model exhibits superior performance in predicting growth kinetics than other models. GBR model fits the experimental results approximately with lower RMSE (0.004) than other models. This enables more accurate representation of growth patterns that is difficult to discernible through conventional analytical methods. This approach will help to understand growth kinetics of acetic acid-producing bacteria for resource recovery, wastewater treatment, and bioremediation.

Microbial Composition, Bioactive Compounds, Potential Benefits and Risks Associated with Kombucha: A Concise Review

Kombucha is a fermented tea beverage containing bioactive compounds from tea and vital compounds such as acetic acid, D-saccharic acid-1,4-lactone, and glucuronic and gluconic acids produced from the metabolic activities of bacteria and yeasts, which benefit human health. Kombucha contains a symbiotic culture of bacteria and yeast (SCOBY), which actively ferments sugar. Kombucha microbial compositions vary due to environmental conditions and the starter culture. Saccharomyces sp., Schizosaccharomyces pombe, Schizosaccharomyces sp., and Brettanomyces sp. (yeasts) and Acetobacter aceti, Komagataeibacter xylinum (formerly known as Gluconacetobacter xylinum), Gluconobacter oxydans, and Acetobacter pasteurianus (acetic acid-producing bacteria) are commonly found in kombucha. This review focused on the microbial compositions of kombucha and their functionality. Aspects discussed include: (i). developments in kombucha, (ii). microbial compositions of kombucha, (ii). microbial production of kombucha cellulose, (iv). factors influencing kombucha microbial compositions, (v). tea type and kombucha bioactive compounds, (vi). kombucha health benefits, and (v). potential risk factors of kombucha consumption. Current gaps, recommendations, and prospects were also discussed. Kombucha production using rooibos as the tea base is recommended, as rooibos is caffeine-free. Upcycling kombucha wastes, mainly SCOBY, for producing cellulose filters, improving food flavors and as a substrate in food fermentations is touched on.

Exploring the nutritional factors and health benefits of artisanal alcoholic rice beverages

Fermentation is an ancient preservation technique used to transform complex food materials into simpler biologically active compounds, which enhances their nutritional content. Various microorganisms, including Lactic acid bacteria, Acetic acid-producing bacteria, moulds, and yeasts, produce a diverse array of compounds ranging from simple saccharides to complex biogenic amines and peptides during fermentation. While fermented foods and beverages are widespread, this review paper focuses on artisanal alcoholic rice beverages (ARB) produced in East Asian nations and some parts of India, where more than 100 varieties are produced by different ethnic communities. The nutritional nature of all ARBs is similar despite the differences in production processes, and a starter cake is used to initiate the fermentation process. The starter cake comprises different plant materials mixed with rice flour, along with a diverse microbial population, including yeast, moulds, and bacteria, that aids in different fermentation stages. Microbes break down starchy materials, produce organic acids and volatile compounds responsible for aroma, and maintain the drink's acidity. The plant materials also act as a microbial reservoir, preventing fermentation spoilage, and enhance the beverage's nutritional quality. This review paper systematically compiles and analyzes the nutritional factors and their potential health benefits from a wide variety of ARB using various databases and search terms. It provides a comprehensive insight into the nutritional factors' functions and possible effects on human health. This review highlights the need for more studies on ARB's microbial composition and nutritional compounds and provides a platform for further research on ARB's nutritional properties.

Effect of riboflavin and carbon black co-modified fillers coupled with alkaline pretreatment on anaerobic digestion of waste activated sludge

Additional various carbon and free riboflavin could improve anaerobic digestion of waste activated sludge (WAS). However, these substances were not reused. In this study, a reusable riboflavin and carbon black (RCB) co-modified filler was developed and combined with alkaline pretreatment for enhancing the production of volatile fatty acids (VFAs) and methane during anaerobic digestion of WAS. The results showed that RCB-modified fillers exhibited a promoting effect on the reduction of alkali-pretreated WAS. The amounts of the accumulated VFAs mainly containing acetate and the produced methane rose with the increased concentration of immobilized riboflavin (0–0.75 g/L) in the presence of 4 g/L carbon black. When the alkaline pretreatment time of WAS increased from 3 d to 8 d, the amount of methane production increased from 22.8% to 63.9% in the presence of 0.75 g/L riboflavin and 4 g/L carbon black compared with that without RCB-modified fillers. Moreover, 0.75 g/L riboflavin and 4 g/L carbon black had a synergetic effect on promoting methane production via broadening extracellular electron transfer pathways. During this process, microbial dehydrogenase activity, electron transport system activity and coenzyme F420 were enhanced. Microbial community analysis showed that RCB-modified filler addition promoted the enrichment of Syntrophomonas and Pseudomonas involved in direct interspecies electron transfer (DIET). These results indicated that DIET establishment was accelerated. Meanwhile, the populations of acetic acid-producing bacteria including Rikenellaceae_RC9_gut_group and Proteiniphilum, aceticlastic and acid-tolerant methanogenic archaea including Methanosarcina and Methanosaeta, RumEn_M2 were increased. These results indicate that RCB-modified fillers coupled with alkaline pretreatment is an effective method to promote the production of methane during anaerobic digestion of WAS.

ISOLATION AND CHARACTERIZATION OF PLANT GROWTH-PROMOTING BACTERIA FROM DIFFERENT RHIZOSPHERIC SOILS

The production of indole acetic acid (IAA) is a significant property of rhizospheric bacteria to stimulate and promote plant growth. In this investigation, indole acetic acid-producing bacteria from the rhizosphere of five distinct plants (Wheat, Gulchen, Rose, Lady Finger, and Bouginvella) were isolated and characterized. Bacterial strains were isolated and identified by morphological characterization. Out of 30 bacterial isolates, 5 isolates were selected as efficient producers of Indole acetic acid. These selected bacterial isolates were subjected to several biochemical tests for identification at the genus level. After the determination of bacterial genus, antibiotic sensitivity test was performed to check the resistance pattern of each bacterial isolate against antibiotics. Selected bacterial isolates were characterized by using molecular techniques. DNA of five bacterial isolates was extracted by WizPrepTMg DNA mini kit and amplification of 16S rRNA gene was done by PCR. Amplification of PCR product was confirmed by agarose gel electrophoresis. From biochemical tests, Klebsiella spp., E. coli, and Bacillus sp. tested positive. Klebsiella spp. showed 87, 88, 81, 88, 91, 100, 90, and 87% resistance against enrofloxacin, gentamycin, penicillin, ampicillin, chlotetracyclin, tylosine, oxytetracycline, and amoxicillin, respectively. E. coli showed 80, 88, 79, 84, 79, 86, 82, and 89% against enrofloxacin, gentamycin, penicillin, ampicillin, chlotetracyclin, tylosine, oxytetracycline, and amoxicillin respectively whereas 87, 91, 100, 100, 93, 100, 89 and 100% resistance was shown by Bacillus sp. against enrofloxacin, gentamycin, penicillin, ampicillin, chlotetracyclin, tylosine, oxytetracycline, and amoxicillin, respectively. All these selected bacterial isolates were found positive for the 16S rRNA gene and characterized as Klebsiella pneumonia RY6, Klebsiella oxytoca strain RY8, Klebsiella oxytoca RY10, Escherichia coli RY20, and Bacillus tequilensis RY23. It is concluded that the property of synthesizing IAA is considered an effective tool for the isolation and characterization of bacteria that have a role in promoting plant growth.

Penggunaan Probiotik Dan Magot Untuk Mereduksi Lalat di Peternakan Ayam Pedaging Muara Selayar Desa Pijot

Chicken manure waste is one of the main problems for large-scale broiler cultivation, especially in areas close to residential areas. The accumulation of manure that accumulates under the cage attracts the arrival and development of the flies in the cultivation site. The development of these flies will spread to the houses of residents who live around the cage. As a result, many farmers stop cultivating the broilers because of public complaints. To overcome this problem, the use of probiotics from acetic acid-producing bacteria can be used to reduce the development of flies because of the ability of the bacteria to reduce the pH of the media and create an uncomfortable environment for egg growth. Likewise, the development of maggot can be a competing medium that beats the flay. In community service activities regarding "The use of probiotics and maggot production to reduce flies in the Muara Selayar broiler farm, Pijot Village, Keruak District, East Lombok Regency". Through this activity, the development of flies can be emphasized by the use of probiotics and the development of magot which can be used as chicken feed.

Isolation and Identification of Indole Acetic Acid (IAA) Producing Bacteria from Organic Soil: Investigating Its Efficacy on Plant Growth

Indole acetic acid (IAA) production is a major property of rhizosphere bacteria that stimulates and facilitates plant growth. The present work deals with the isolation, characterization, and identification of indole acetic acid-producing bacteria from the rhizospheric soil. Out of four organisms isolated from serial dilution, Sample-2 confirmed thick bands of IAA production by TLC analysis. 16s rRNA analysis showed the isolated organism was found to be Pseudomonas fluorescence with a similarity of 88%. The isolated organism treat plants showed increased shoot and root length in plant growth analysis. In conclusion, the isolated IAA-producing bacteria can be used as efficient biofertilizer inoculants to promote plant growth.

Quantitative assay of Indole Acetic Acid-producing bacteria isolated from several lakes in East Java, Indonesia

Abstract. Ramadhani SI, Prabaningtyas S, Witjoro A, Saptawati TR, Rodiansyah A. 2020. Quantitative assay of Indole Acetic Acid-producing bacteria isolated from several lakes in East Java, Indonesia. Biodiversitas 21: 5448-5454. Biofuel is an alternative to fossil fuels that are environmentally friendly with low emissions. Biofuel from biomass microalgae, especially Chlorella vulgaris, has an essential role in biofuel production. Increasing biomass microalgae was done by co-culture between microalgae and bacteria. This research aims to determine the potential of bacterial isolates to produce the IAA hormone and identify the highest isolate with the ability to synthesis IAA from four lakes in East Java. This research was conducted by culturing bacterial isolates in the Tryptic Soy Broth (TSB) to add tryptophan media in various periods of incubation. The absorbance was measured with UV-Vis spectrophotometry at a wavelength of 530 nm for determining IAA-production from bacterial isolates. The results showed that the "12" code bacterial isolate from Ranu Grati produced the highest IAA hormone concentration, with an average of 30.23 ppm. The morphological characterization of the highest IAA-producing bacteria showed that isolate included the Enterobacteriaceae group and phenotypic characterization include Enterobacter cloacae complex (ECC).

Utilization of Kefir Beverages as a Preventive Action Part of Pneumonia Infection

Introduction: Pneumonia is an acute infection of the lungs and can be caused by bacteria, viruses, fungi, chemical exposure or the influence of other infections. Pneumonia is one of the diseases that cause the most deaths in the world after diarrhoea. Pneumonia caused by several microorganisms includes Haemophilus influenza type B (HiB), Streptococcus pneumonia, influenza virus and respiratory syncytial virus (RSV). The use of antibiotics is now one of the important treatments for the management of pneumonia. However, with the challenge of antimicrobial resistance, therapy is needed to eradicate pathogens and prevent resistance. One probiotic drink that has potential in the treatment of pneumonia is kefir. The development of science now shows the potential of kefir probiotic drinks to prevent pneumonia infection.
 Discussion: This literature study proves that probiotic drinks have an antibacterial effect to prevent pneumonia infection. The complex content of probiotic bacteria between specific lactic acid bacteria, acetic acid-producing bacteria and lactose and non-lactose fermenting bacteria that symbiotic with each other stimulates the immune system to be used for pathogens of pneumonia infection. The component of probiotic bacteria in kefir can reduce the level of antibiotic and antimicrobial consumption which can complicate the treatment of pneumonia infections.
 Conclusion: Probiotic drinks from kefir which have a high content of probiotic bacteria can reduce the risk of pneumonia infection

Acetic acid and butyric acid released in large intestine play different roles in the alleviation of constipation

Abstract Constipation is a disorder that affects people of all ages. Previous study showed Bifidobacterium spp. altered the faecal concentrations of short-chain fatty acids (SCFAs) while relieving constipation. Therefore, we speculated SCFAs might relieve constipation. We evaluated constipation-related indicators, SCFA levels and the faecal microbiota of constipated mice that were fed acylated starches derived from specific SCFAs for 1 month. It confirmed application of acylated starches resolved the issue of SCFAs absorption in small intestine by measuring the concentration of different SCFA in various tissues. Acetylated starch relieved constipation by increasing acetic acid-producing bacteria that were correlated positively with the small intestinal transit rate and water content of faeces, while butylated starch relieved constipation by increasing butyric acid-producing bacteria that were correlated negatively with the time to the first black stool defecation. These results indicated acetic acid and butyric acid play different roles in relieving constipation.

A Modified, Efficient and Sensitive pH Indicator Dye Method for the Screening of Acid-Producing Acetobacter Strains Having Potential Application in Bio-Cellulose Production.

It is imperative that promising bacterial cellulose-producing bacteria mainly belongs to genera Acetobacter (acid-producing bacteria). In order to screen cellulose-producing Acetobacter, the isolated cultures from vinegar/rotten fruits were inoculated in Hestrin-Schramm (HS) medium containing ethanol and CaCO3. After the desired incubation, the positive cultures form a zone, which is observed around the bacterial growth, resulted from the solubilization of CaCO3 by acetic acid produced from the oxidation of ethanol during fermentation. However, in this method, the clarity of the solubilized zone is not very sharp and distinct. In the present, investigation, an improved method for screening, of the microorganisms producing acetic acid has been developed. In this method, methyl red (MR) is incorporated as a pH indicator in HS medium containing ethanol and CaCO3. Plates containing MR at alkaline pH are yellow and turn dark red at acidic pH. Thus, a distinctive, clear zone is formed around bacterial colonies producing acetic acid and is easy to differentiate between acid producers and non-producers. The present method is more rapid, accurate, and sensitive and can be successfully be used for the detection of acetic acid-producing bacteria particularly for the screening of potent cellulose producer Acetobacter sp.

Dietary Clostridium butyricum Induces a Phased Shift in Fecal Microbiota Structure and Increases the Acetic Acid-Producing Bacteria in a Weaned Piglet Model.

Clostridium butyricum is known as a butyrate producer and a regulator of gut health, but whether it exerts a beneficial effect as a dietary supplement via modulating the intestinal microbiota remains elusive. This study investigated the impact of C. butyricum on the fecal microbiota composition and their metabolites 14 and 28 days after weaning with 10 g/kg dietary supplementation of C. butyricum. Dynamic changes of microbial compositions showed dramatically increasing Selenomonadales and decreasing Clostridiales on days 14 and 28. Within Selenomonadales, Megasphaera became the main responder by increasing from 3.79 to 11.31%. Following the prevalence of some acetate producers ( Magasphaera) and utilizers ( Eubacterium_hallii) at the genus level and even with a significant decrease in fecal acetate on day 28, the present data suggested that C. butyricum influenced microbial metabolism by optimizing the structure of microbiota and enhancing acetate production and utilization for butyrate production.

Vinegar Treatment Prevents the Development of Murine Experimental Colitis via Inhibition of Inflammation and Apoptosis.

This study investigated the preventive effects of vinegar and acetic acid (the active component of vinegar) on ulcerative colitis (UC) in mice. Vinegar (5% v/v) or acetic acid (0.3% w/v) treatment significantly reduced the disease activity index and histopathological scores, attenuated body weight loss, and shortened the colon length in a murine experimental colitis model induced by dextran sulfate sodium (DSS). Further mechanistic analysis showed that vinegar inhibited inflammation through suppressing Th1 and Th17 responses, the NLRP3 inflammasome, and MAPK signaling activation. Vinegar also inhibited endoplasmic reticulum (ER) stress-mediated apoptosis in the colitis mouse model. Surprisingly, pretreatment with vinegar for 28 days before DSS induction increased levels of the commensal lactic acid-producing or acetic acid-producing bacteria, including Lactobacillus, Bifidobacteria, and Enterococcus faecalis, whereas decreased Escherichia coli levels were found in the feces of mice. These results suggest that vinegar supplementation might provide a new dietary strategy for the prevention of UC.

Occurrence of High Acetic Acid-Producing Bacteria in Ivorian Cocoa Fermentation and Analysis of Their Response to Fermentative Stress

Acetic acid produced during cocoa fermentation impact strongly the quality of fermented and dried cocoa beans and chocolate. The objective of this study was to analyze acid production in Acetic acid bacteria (AAB) and their response to fermentative conditions. AAB strains were isolated from cocoa fermentation and screened for acid production on both solid and liquid media. From 444 isolates, 15 strains yielded 2 to 38.1 g/L of acid in liquid medium. The best acid producers were identified by biochemical typing as Acetobactersp, Acetobacteraceti, A. peroxydans, A. pasteurianus and Gluconobacteroxydans. Most AAB strains showed strong tolerance to alcohol with round 45% of survival growth rate (SGR) under 12 % ethanol. AAB strains growing well at 2 % acetic acid (SGRround 47 %), failed to grow at 3 % of this acid. Lactic acid has the most hindering effect on AAB growth, provoking a drop of SGR from 100 % to less than 25 % at only 1 % of lactic acid. Maximum growth of acidifying AAB strains occurred at 35 °C. This study evidences the diversity of technological performances of AAB involved in Ivorian cocoa fermentation and allows targeting the most valuable strains as starters.

Kombucha fermentation and its antimicrobial activity.

Kombucha was prepared in a tea broth (0.5% w/v) supplemented with sucrose (10% w/v) by using a commercially available starter culture. The pH decreased steadily from 5 to 2.5 during the fermentation while the weight of the "tea fungus" and the OD of the tea broth increased through 4 days of the fermentation and remained fairly constant thereafter. The counts of acetic acid-producing bacteria and yeasts in the broth increased up to 4 days of fermentation and decreased afterward. The antimicrobial activity of Kombucha was investigated against a number of pathogenic microorganisms. Staphylococcus aureus, Shigella sonnei, Escherichia coli, Aeromonas hydrophila, Yersinia enterolitica, Pseudomonas aeruginosa, Enterobacter cloacae, Staphylococcus epidermis, Campylobacter jejuni, Salmonella enteritidis, Salmonella typhimurium, Bacillus cereus, Helicobacterpylori, and Listeria monocytogenes were found to be sensitive to Kombucha. According to the literature on Kombucha, acetic acid is considered to be responsible for the inhibitory effect toward a number of microbes tested, and this is also valid in the present study. However, in this study, Kombucha proved to exert antimicrobial activities against E. coli, Sh. sonnei, Sal. typhimurium, Sal. enteritidis, and Cm. jejuni, even at neutral pH and after thermal denaturation. This finding suggests the presence of antimicrobial compounds other than acetic acid and large proteins in Kombucha.