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Bioscience, Biotechnology, and... Apr 2024Gluconobacter strains perform incomplete oxidation of various sugars and alcohols, employing regio- and stereoselective membrane-bound dehydrogenases oriented toward the... (Review)
Review
Gluconobacter strains perform incomplete oxidation of various sugars and alcohols, employing regio- and stereoselective membrane-bound dehydrogenases oriented toward the periplasmic space. This oxidative fermentation process is utilized industrially. The ketogluconate production pathway, characteristic of these strains, begins with the conversion of d-glucose to d-gluconate, which then diverges and splits into 2 pathways producing 5-keto-d-gluconate and 2-keto-d-gluconate and subsequently 2,5-diketo-d-gluconate. These transformations are facilitated by membrane-bound d-glucose dehydrogenase, glycerol dehydrogenase, d-gluconate dehydrogenase, and 2-keto-d-gluconate dehydrogenase. The variance in end products across Gluconobacter strains stems from the diversity of enzymes and their activities. This review synthesizes biochemical and genetic knowledge with biotechnological applications, highlighting recent advances in metabolic engineering and the development of an efficient production process focusing on enzymes relevant to the ketogluconate production pathway in Gluconobacter strains.
Topics: Gluconates; Gluconobacter; Biotechnology; Fermentation; Metabolic Engineering; Glucose; Glucose 1-Dehydrogenase; Sugar Alcohol Dehydrogenases
PubMed: 38323387
DOI: 10.1093/bbb/zbae013 -
Biochimica Et Biophysica Acta.... Mar 2024Membranous Extracellular Vesicles (EVs) of Gram-negative bacteria are a secretion and delivery system that can disseminate bacterial products and interact with hosts and...
Extracellular membrane vesicles derived from Komagataeibacter oboediens exposed on the International Space Station fuse with artificial eukaryotic membranes in contrast to vesicles of reference bacterium.
Membranous Extracellular Vesicles (EVs) of Gram-negative bacteria are a secretion and delivery system that can disseminate bacterial products and interact with hosts and the environment. EVs of nonpathogenic bacteria deliver their contents by endocytosis into eukaryotic cells, however, no evidence exists for a fusion delivery mechanism. Here, we describe the fusion of exposed to space/Mars-like stressors simulated on the International Space Station vesicles (E-EVs) from Komagataeibacter oboediens to different types of model planar membranes in comparison with the EVs of the ground-based reference strain. The most reliable fusion was achieved with PC:PE:ergosterol or sterol-free PC:PE bilayers. The relative permeability ratio (PK+/PCl-) estimated from the shift of zero current potential according to Goldman-Hodgkin-Katz equation consisted of 4.17 ± 0.48, which coincides with preferential cation selectivity of the EV endogenous channels. The increase in membrane potential from 50 mV to 100 mV induced the fusion of E-EVs with all tested lipid compositions. The fusion of model exosomes with planar bilayer lipid membranes was confirmed by separate step-like increases in its conductance. In contrast, the ground-based reference K. oboediens EVs never induced the fusion event. In our study, we show membrane lipidome perturbations and increased protein aggregation occurred in the exposed samples in the harsh environment when outer membranes of K. oboediens acquired the capability of both homo- and heterotypic fusion possibly by altered membrane fluidity and the pore-forming capability.
Topics: Membranes, Artificial; Membrane Fusion; Lipid Bilayers; Extracellular Vesicles; Bacteria; Acetobacteraceae
PubMed: 38281706
DOI: 10.1016/j.bbamem.2024.184290 -
Microorganisms Dec 2023Fermented milk products (FMPs) contain probiotics that are live bacteria considered to be beneficial to human health due to the production of various bioactive...
Fermented milk products (FMPs) contain probiotics that are live bacteria considered to be beneficial to human health due to the production of various bioactive molecules. In this study, nine artisanal FMPs (kefir, ayran, khurunga, shubat, two cottage cheeses, bryndza, khuruud and suluguni-like cheese) from different regions of Russia were characterized using metagenomics. A metagenomic sequencing of ayran, khurunga, shubat, khuruud and suluguni-like cheese was performed for the first time. The taxonomic profiling of metagenomic reads revealed that species, such as and prevailed in khuruud, bryndza, one sample of cottage cheese and khurunga. The latter one together with suluguni-like cheese microbiome was dominated by bacteria, affiliated to (32-35%). In addition, a high proportion of sequences belonging to the genera and but not classified at the species level were found in the suluguni-like cheese. , as well as constituted the majority in another cottage cheese, kefir and ayran metagenomes. The microbiome of shubat, produced from camel's milk, was significantly distinctive, and , and represented the dominant components (42, 7.4 and 5.6%, respectively). In total, 78 metagenome-assembled genomes with a completeness ≥ 50.2% and a contamination ≤ 8.5% were recovered: 61 genomes were assigned to the , and families (the order within ), 4 to (the phylum) and 2 to (the phylum). A metagenomic analysis revealed numerous genes, from 161 to 1301 in different products, encoding glycoside hydrolases and glycosyltransferases predicted to participate in lactose, alpha-glucans and peptidoglycan hydrolysis as well as exopolysaccharides synthesis. A large number of secondary metabolite biosynthetic gene clusters, such as lanthipeptides, unclassified bacteriocins, nonribosomal peptides and polyketide synthases were also detected. Finally, the genes involved in the synthesis of bioactive compounds like β-lactones, terpenes and furans, nontypical for fermented milk products, were also found. The metagenomes of kefir, ayran and shubat was shown to contain either no or a very low count of antibiotic resistance genes. Altogether, our results show that traditional indigenous fermented products are a promising source of novel probiotic bacteria with beneficial properties for medical and food industries.
PubMed: 38276185
DOI: 10.3390/microorganisms12010016 -
International Journal of Biological... Mar 2024Bacterial cellulose (BC) is a remarkable biomacromolecule with potential applications in food, biomedical, and other industries. However, the low economic feasibility of...
Bacterial cellulose (BC) is a remarkable biomacromolecule with potential applications in food, biomedical, and other industries. However, the low economic feasibility of BC production processes hinders its industrialization. In our previous work, we obtained candidate strains with improved BC production through random mutations in Gluconacetobacter. In this study, the molecular identification of LYP25 strain with significantly improved productivity, the development of chestnut pericarp (CP) hydrolysate medium, and its application in BC fermentation were performed for cost-effective BC production process. As a result, the mutant strain was identified as Gluconacetobacter xylinus. The CP hydrolysate (CPH) medium contained 30 g/L glucose with 0.4 g/L acetic acid, whereas other candidates known to inhibit fermentation were not detected. Although acetic acid is generally known as a fermentation inhibitor, it improves the BC production by G. xylinus when present within about 5 g/L in the medium. Fermentation of G. xylinus LYP25 in CPH medium resulted in 17.3 g/L BC, a 33 % improvement in production compared to the control medium, and BC from the experimental and control groups had similar physicochemical properties. Finally, the overall process of BC production from biomass was evaluated and our proposed platform showed the highest yield (17.9 g BC/100 g biomass).
Topics: Acetic Acid; Gluconacetobacter xylinus; Cellulose; Biomass; Fermentation
PubMed: 38266828
DOI: 10.1016/j.ijbiomac.2024.129597 -
International Journal of Biological... Mar 2024Bacterial cellulose (BC), a nanostructured material, is renowned for its excellent properties. However, its production by bacteria is costly due to low medium...
Bacterial cellulose (BC), a nanostructured material, is renowned for its excellent properties. However, its production by bacteria is costly due to low medium utilization and conversion rates. To enhance the yield of BC, this study aimed to increase BC yield through genetic modification, specifically by overexpressing bcsC and bcsD in Gluconacetobacter xylinus, and by developing a modified culture method to reduce medium viscosity by adding water during fermentation. As a result, BC yields of 5.4, 6.2, and 6.8 g/L were achieved from strains overexpressing genes bcsC, bcsD, and bcsCD, significantly surpassing the yield of 2.2 g/L from wild-type (WT) strains. In the modified culture, the BC yields of all four strains increased by >1 g/L with the addition of 20 mL of water during fermentation. Upon comparing the properties of BC, minimal differences were observed between the WT and pbcsC strains, as well as between the static and modified cultures. In contrast, BC produced by strains overexpressing bcsD had a denser microstructural network and exhibited demonstrated higher tensile strength and elongation-to-break. Compared to WT, BC from bcsD overexpressed strains also displayed enhanced crystallinity, higher degree of polymerization and improved thermal stability.
Topics: Gluconacetobacter xylinus; Cellulose; Fermentation; Nanostructures; Water
PubMed: 38242407
DOI: 10.1016/j.ijbiomac.2024.129552 -
Overproduction of bacterial cellulose from Acetobacter xylinum BPR2001 using food industries wastes.Biotechnology and Applied Biochemistry Jun 2024In this study, a cost-effective complex culture media containing molasses and corn steep liquor (CSL) was developed for the high production of bacterial cellulose (BC)...
In this study, a cost-effective complex culture media containing molasses and corn steep liquor (CSL) was developed for the high production of bacterial cellulose (BC) by investigating the effect of four effective factors on BC production at three levels using Taguchi and combined methods. The predicted and actual values of BC production in optimal conditions by Taguchi and combined methods were 8.41 and 14.52 g/L, respectively. These results showed that the combined method was more suitable for predicting the optimal conditions in the optimization of BC production, the cost of developed culture medium was around 94% cost of HS medium preparation, molasses was the most effective factor in both experimental design methods, and initial pH adjustment had little impact on BC production. Then, the effect of inoculation conditions containing three factors of inoculation age, ethanol addition time, and agitation rate on the increase of BC production at three levels was investigated using the response surface methodology with the Box-Behnken design algorithm. Under the optimal conditions including inoculum age of 3 days, ethanol addition time of 10 days, and stirring speed of 100 rpm, the predicted and experimental results of BC production were 21.61 and 20.21 g/L, respectively. This is among the highest ever reported for BC production, which was achieved with a more cost-effective culture medium containing molasses and CSL.
Topics: Cellulose; Gluconacetobacter xylinus; Food Industry; Industrial Waste; Culture Media; Molasses
PubMed: 38233730
DOI: 10.1002/bab.2560 -
Food Research International (Ottawa,... Feb 2024Highland barley vinegar, as a solid-state fermentation-type vinegar emerged recently, is well-known in Qinghai-Tibet plateau area of China. This work aimed to explore...
Highland barley vinegar, as a solid-state fermentation-type vinegar emerged recently, is well-known in Qinghai-Tibet plateau area of China. This work aimed to explore the main physicochemical factors, key flavor volatile compounds, and dominate microorganisms of highland barley vinegar during fermentation. The results showed that the decrease trend of reducing sugar, pH and the increase trend of amino acid nitrogen were associated with the metabolism of dominate bacteria, especially Lactobacillus and Acetobacter. Totally, 35 volatile compounds mainly including 20 esters, 10 alcohols, 2 aldehydes, 1 ketone and 2 pyrazines and 7 organic acids were identified. Especially, isoamyl acetate, acetyl methyl carbinol, ethyl caprylate, 1,2-propanediol, 3-methyl-1-butanol and ethyl isovalerate with high odor activity values were confirmed as key aroma compounds. Meanwhile, the relative average abundance of bacteria at genus level decreased significantly as fermentation time goes on. Among these microbes, Lactobacillus were the dominate bacteria at alcohol fermentation stage, Lactobacillus and Acetobacter were dominate at acetic acid fermentation stage. Furthermore, the correlations between dominate bacteria and the key volatile compounds were revealed, which highlighted Lactobacillus and Acetobacter were significantly correlated with key volatile compounds (|r| > 0.5, P < 0.01). The fundings of this study provide insights into the flavor and assist to improve the production quality of highland barley vinegar.
Topics: Acetic Acid; Hordeum; Fermentation; Alcohols; Bacteria; Acetobacter
PubMed: 38225120
DOI: 10.1016/j.foodres.2023.113919 -
International Journal of Systematic and... Jan 2024A recent modification of the Note to Rule 25a of the International Code for Nomenclature of Bacteria is used by the List Editors of the to justify the refusal to...
A recent modification of the Note to Rule 25a of the International Code for Nomenclature of Bacteria is used by the List Editors of the to justify the refusal to validate species protologues published in supplementary material to this formal decision. Authors are therefore forced to ask permission to reuse published data for the valid publication of such names. In the present letter we re-publish the species protologues of sp. nov., sp. nov. and sp. nov.
Topics: Animals; Phylogeny; Sequence Analysis, DNA; RNA, Ribosomal, 16S; DNA, Bacterial; Bacterial Typing Techniques; Base Composition; Fatty Acids; Acetobacteraceae; Insecta
PubMed: 38180323
DOI: 10.1099/ijsem.0.006224 -
Applied Microbiology and Biotechnology Dec 2024Gastric and colorectal cancer are among the most frequently diagnosed malignancies of the gastrointestinal tract. Searching for methods of therapy that complements...
Gastric and colorectal cancer are among the most frequently diagnosed malignancies of the gastrointestinal tract. Searching for methods of therapy that complements treatment or has a preventive effect is desirable. Bacterial metabolites safe for human health, which have postbiotic effect, are of interest recently. The study aimed to preliminary assessment of the safety, antimicrobial, and anti-cancer activity of cell-free metabolites of Gluconobacter oxydans strains isolated from Kombucha beverages as an example of the potential postbiotic activity of acetic acid bacteria (AAB). The study material consisted of five AAB strains of Kombucha origin and three human cell lines (gastric adenoma-AGS, colorectal adenoma-HT-29, and healthy cells derived from the endothelium of the human umbilical vein-HUVEC). Results of the study confirms the health safety and functional properties of selected AAB strains, including their potential postbiotic properties. The best potential anticancer activity of the AAB cell-free supernatants was demonstrated against AGS gastric adenoma cells. The conducted research proves the postbiotic potential of selected acetic acid bacteria, especially the KNS30 strain. KEY POINTS: •The beneficial and application properties of acetic acid bacteria are poorly studied. •Gluconobacter oxydans from Kombucha show a postbiotic activity. •The best anticancer activity of the G. oxydans showed against gastric adenoma.
Topics: Humans; Gluconobacter oxydans; Acetic Acid; Adenoma
PubMed: 38157006
DOI: 10.1007/s00253-023-12915-4 -
Journal of Insect Physiology Mar 2024Numerous studies have demonstrated the vital roles of gut microbes in the health, immunity, nutrient metabolism, and behavior of adult worker honeybees. However, a few...
Numerous studies have demonstrated the vital roles of gut microbes in the health, immunity, nutrient metabolism, and behavior of adult worker honeybees. However, a few studies have been conducted on gut microbiota associated with the larval stage of honeybees. In the present study, we explored the role of a gut bacterium in larval development and larval-pupal transition in the Asian honeybee, Apis cerana. First, our examination of gut microbial profiling showed that Bombella apis, a larvae-associated bacterium, was the most dominant bacterium colonized in the fifth instar larvae. Second, we demonstrated that tetracycline, an antibiotic used to treat a honeybee bacterial brood disease, could cause the complete depletion of gut bacteria. This antibiotic-induced gut microbiome depletion in turn, significantly impacted the survivorship, pupation rate and emergence rate of the treated larvae. Furthermore, our analysis of gene expression pattens revealed noteworthy changes in key genes. The expression of genes responsible for encoding storage proteins vitellogenin (vg) and major royal jelly protein 1 (mrjp1) was significantly down-regulated in the tetracycline-treated larvae. Concurrently, the expression of krüppel homolog 1(kr-h1), a pivotal gene in endocrine signaling, increased, whilethe expression of broad-complex (br-c) gene that plays a key role in the ecdysone regulation decreased. These alterations indicated a disruption in the coordination of juvenile hormone and ecdysteroid synthesis. Finally, we cultivated B. apis isolated from the fifth instar worker larval of A. cerana and fed tetracycline-treated larvae with a diet replenished by B. apis. This intervention resulted in a significant improvement in the pupation rate, emergence rate, and overall survival rate of the treated larvae. Our findings demonstrate the positive impact of B. apis on honeybee larvae development, providing new evidence of the functional capacities of gut microbes in honeybee growth and development.
Topics: Bees; Animals; Larva; Pupa; Insect Proteins; Anti-Bacterial Agents; Tetracyclines; Acetobacteraceae
PubMed: 38142957
DOI: 10.1016/j.jinsphys.2023.104601