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We provide a culturomics analysis of the cultivable bacterial communities of the crop, midgut and hindgut compartments, as well as the ovaries, of the invasive insect Vespa velutina, along with a cultivation-independent analysis of samples of the same nest through 16S rRNA amplicon sequencing. The Vespa velutina bacterial symbiont community was dominated by the genera Convivina, Fructobacillus, Lactiplantibacillus, Lactococcus, Sphingomonas and Spiroplasma. Lactococcus lactis and Lactiplantibacillus plantarum represented generalist core lactic acid bacteria (LAB) symbionts, while Convivina species and Fructobacillus fructosus represented highly specialised core LAB symbionts with strongly reduced genome sizes. Sphingomonas and Spiroplasma were the only non-LAB core symbionts but were not isolated. Convivina bacteria were particularly enriched in the hornet crop and included Convivina intestini, a species adapted towards amino acid metabolism, and Convivina praedatoris sp. nov. which was adapted towards carbohydrate metabolism.

Acetic acid bacteria (family Acetobacteraceae ) are found in the gut of most insects. Two clades are currently recognized: Commensalibacter–Entomobacter and Bombell a– Oecophyllibacter . The latter group is only found in hymenopteran insects and the described species have been isolated from bees and ants. In this study, two new strains DDB2-T1T (=KACC 21507T=LMG 31759T) and DM15PD (=CCM 9165=DSM 112731=KACC 22353=LMG 32454) were isolated from wasps collected in the Republic of Korea and Germany, respectively. Molecular and phenotypic analysis revealed that the strains are closely related, with 16S rRNA gene sequences showing 100 % identity and genomic average nucleotide identity (ANI) values ≥99 %. The closest related species based on type strain 16S rRNA gene sequences are Swingsia samuiensis , Acetobacter peroxydans , Bombella favorum and Bombella intestini (94.8–94.7% identity), whereas the closest related species based on type strain genome analysis are Saccharibacter floricola and Bombella intestini (ANI values of 68.8 and 68.2 %, respectively). The reconstruction of a phylogenomic tree based on 107 core proteins revealed that the branch leading to DDB2-T1T and DM15PD is localized between Oecophyllibacter and Saccharibacter–Bombella. Further genomic distance metrics such as ANI, percentage of conserved proteins and alignment fraction values were consistent with these strains belonging to a new genus. The key phenotypic characteristics were one MALDI-TOF-MS peak (m/z=4601.9±2.0) and the ability to produce acid from d-arabinose. Based on this polyphasic approach, including phylogenetics, phylogenomics, genome distance calculations, ecology and phenotypic characteristics, we propose to name the novel strains Aristophania vespae gen. nov., sp. nov., with the type strain DDB2-T1T (=KACC 21507T=LMG 31759T).

Wort was prepared according to the Congress mash protocol with the addition of 40% unmalted barley, tritordeum, or quinoa. Mashes with quinoa filtered significantly slower than mashes with barley. ...

Strain C17-3T was isolated from blueberry fruits collected from a farmland located in Damyang-gun, Jeollanam-do, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences allocated strain C17-3T to the genus Acetobacter , where it occupied a rather isolated line of descent with Acetobacter ghanensis 430AT and Acetobacter lambici LMG 27439T as the nearest neighbours (98.9 % sequence similarity to both species). The highest average nucleotide identity and digital DNA–DNA hybridization values were 76.3 % and 21.7 % with Acetobacter garciniae TBRC 12339T; both values were well below the cutoff values for species delineation. Cells are strictly aerobic, Gram-stain-negative rods, catalase-positive and oxidase-negative. The DNA G+C content calculated from the genome sequence was 59.2 %. Major fatty acids were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c) and C19 : 0cyclo ω8c. The major isoprenoid quinone was ubiquinone 9. On the basis of the results of phylogenetic analyses, phenotypic features and genomic comparisons, it is proposed that strain C17-3T represents a novel species of the genus Acetobacter and the name Acetobacter vaccinii sp. nov. is proposed. The type strain is C17-3T (= KACC 21233T = LMG 31758T).

Kombucha tea is made by aerobically fermenting a sweetened tea infusion with a kombucha culture, a symbiotic culture of bacteria and yeasts. The resulting beverage is usually non-alcoholic, sour an...

Eleven series of water kefir fermentation processes differing in the presence of oxygen and the type and concentration of inoculum and substrate, were followed as a function of time to quantify the impact of these parameters on the kinetics of this process via a modeling approach. Increasing concentrations of the water kefir grain inoculum increased the water kefir fermentation rate, so that the metabolic activity during water kefir fermentation was mainly associated with the grains. Water kefir liquor could also be used as an alternative means of inoculation, but the resulting fermentation process progressed slower than the one inoculated with water kefir grains, and the production of water kefir grain mass was absent. Substitution of sucrose with glucose and/or fructose reduced the water kefir grain growth, whereby glucose was fermented faster than fructose. Lacticaseibacillus paracasei (formerly known as Lactobacillus paracasei), Lentilactobacillus hilgardii (formerly known as Lactobacillus hilgardii), Liquorilactobacillus nagelii (formerly known as Lactobacillus nagelii), Saccharomyces cerevisiae, and Dekkera bruxellensis were the main microorganisms present. Acetic acid bacteria were present in low abundances under anaerobic conditions and only proliferated under aerobic conditions. Visualization of the water kefir grains through scanning electron microscopy revealed that the majority of the microorganisms was attached onto their surface. Lactic acid bacteria and yeasts were predominantly associated with the grains, whereas acetic acid bacteria were predominantly associated with the liquor.

Eight water kefir fermentation series differing in buffer capacity and calcium concentration of the water used for fermentation were studied during eight backslopping steps. High buffer capacities resulted in high pH values and high calcium concentrations resulted in low pH values at the end of each backslopping step. When the water buffer capacity and/or calcium concentration were below certain minima, the water kefir grain growth decreased gradually over multiple backsloppings. High water buffer capacities resulted in high concentrations of residual total carbohydrate concentrations and low metabolite concentrations. Further, high water buffer capacities resulted in high ratios of lactic acid bacteria to yeasts, which was reflected in high molar ratios of the concentrations of lactic acid to ethanol and acetic acid to ethanol. The most prevalent microorganisms of the water kefir grain inoculum and grains of all fermentation series at the end of the eighth backslopping step were Lactobacillus hilgardii, Lactobacillus nagelii, Lactobacillus paracasei, Bifidobacterium aquikefiri, Saccharomyces cerevisiae, and Dekkera bruxellensis. These microbial communities were influenced by the water buffer capacity and had an impact on the substrate consumption and metabolite production during water kefir fermentation.

Aims To investigate the influence of the water kefir grain inoculum on the characteristics of the water kefir fermentation process. Methods and results Three water kefir fermentation processes were started with different water kefir grain inocula and followed as a function of time regarding microbial species diversity, community dynamics, substrate consumption profile, and metabolite production course. The inoculum determined the water kefir grain growth, the viable counts on the grains, the time until total carbohydrate exhaustion, the final metabolite concentrations, and the microbial species diversity. There were always 2-10 lactic acid bacterial cells for every yeast cell and the majority of these microorganisms was always present on the grains. Lactobacillus paracasei, Lactobacillus hilgardii, Lactobacillus nagelii, and Saccharomyces cerevisiae were always present and may be the key microorganisms during water kefir fermentation. Low water kefir grain growth was associated with small grains with high viable counts of microorganisms, fast fermentation, and low pH values, and was not caused by the absence of exopolysaccharide-producing lactic acid bacteria. Conclusions The water kefir grain inoculum influences the microbial species diversity and characteristics of the fermentation process. A select group of key microorganisms was always present during fermentation. Significance and Impact of the Study This study allows a rational selection of a water kefir grain inoculum. This article is protected by copyright. All rights reserved.

A poorly performing industrial water kefir production process consisting of a first fermentation process, a rest period at low temperature, and a second fermentation process was characterized to elucidate the causes of its low water kefir grain growth and instability. The frozen-stored water kefir grain inoculum was thawed and reactivated during three consecutive prefermentations before the water kefir production process was started. Freezing and thawing damaged the water kefir grains irreversibly, as their structure did not restore during the prefermentations nor the production process. The viable counts of the lactic acid bacteria and yeasts on the water kefir grains and in the liquors were as expected, whereas those of the acetic acid bacteria were high, due to the aerobic fermentation conditions. Nevertheless, the fermentations progressed slowly, which was caused by excessive substrate concentrations resulting in a high osmotic stress. Lactobacillus nagelii, Lactobacillus paracasei, Lactobacillus hilgardii, Leuconostoc mesenteroides, Bifidobacterium aquikefiri, Gluconobacter roseus/oxydans, Gluconobacter cerinus, Saccharomyces cerevisiae, and Zygotorulaspora florentina were the most prevalent microorganisms. Lb. hilgardii, the microorganism thought to be responsible for water kefir grain growth, was not found culture-dependently, which could explain the low water kefir grain growth of this industrial process.

A novel Bifidobacterium, strain LMG 28769T, was isolated from a household water kefir fermentation process. The cells were Gram-stain-positive, non-motile, non-spore-forming, catalase-negative, oxidase-negative, and facultatively anaerobic short rods. Analysis of its 16S rRNA gene sequence revealed Bifidobacterium crudilactis and Bifidobacterium psychraerophilum (97.4 % and 97.1 % similarity towards the respective type strain sequences) as nearest phylogenetic neighbors. Its assignment to the genus Bifidobacterium was confirmed by the presence of fructose 6-phosphate phosphoketolase (F6PPK) activity. Analysis of the hsp60 gene sequence revealed a very low similarity with nucleotide sequences in the NCBI nucleotide database. The genotypic and phenotypic analyses allowed to differentiate strain LMG 28769T from all established Bifidobacterium species. Strain LMG 28769T (= CCUG 67145T = R-54638T) therefore represents a new species, for which the name Bifidobacterium aquikefiri sp. nov. is proposed.

Eight water kefir fermentation series differing in the presence of oxygen, the nutrient concentration, and the nutrient source were studied during eight consecutive backslopping steps. The presence of oxygen allowed the proliferation of acetic acid bacteria, resulting in high concentrations of acetic acid, and decreased the relative abundance of Bifidobacterium aquikefiri. Low nutrient concentrations resulted in slow water kefir fermentation and high pH values, which allowed the growth of Comamonas testosteroni/thiooxydans. Further, low nutrient concentrations favored the growth of Lactobacillus hilgardii and Dekkera bruxellensis, whereas high nutrient concentrations favored the growth of Lactobacillus nagelii and Saccharomyces cerevisiae. Dried figs, dried apricots, and raisins resulted in stable water kefir fermentation. Water kefir fermentation with dried apricots resulted in the highest pH and water kefir grain growth, whereas that with raisins resulted in the lowest pH and water kefir grain growth. Further, water kefir fermentation with raisins resembled fermentations with low nutrient concentrations, that with dried apricots resembled fermentations with normal nutrient concentrations, and that with fresh figs or a mixture of yeast extract and peptone resembled fermentations with high nutrient concentrations.

Acetic acid bacteria (AAB) are mainly associated with the biotechnological process of vinegar and cellulose production, and although their occurrence in natural fermentation systems has been substantiated, their role remains rather unclear. Members of the Acetobacteraceae phylogenetic group have been reported in a range of spontaneous fermentations, such as the last phase of the cocoa bean fermentation process, the manufacturing of acidic beers, and several other slightly acidic beverages (e.g., kombucha, milk kefir, water kefir). In general, AAB are fastidious and obligate aerobes, although they can remain in a viable but nonculturable state when oxygen levels are low, and thus they are regarded as cumbersome to cultivate or isolate using laboratory media. Currently, with the implementation of culture-independent methods, as well as the introduction of metagenomics and high-throughput sequencing technologies, the abundance and functionalities of AAB in food commodities are being determined. Despite their sporadic isolation or incidence in fermentation ecosystems, the genera Acetobacter, Gluconobacter, Gluconacetobacter, and Komagataeibacter constitute the most frequently encountered taxa. The complete genome sequencing of strains of representative AAB species has elucidated the gene repertoires related to interesting metabolic features, facilitating the understanding of the key role of AAB in natural fermentation ecosystems.

Background Water kefir is a slightly sweet, acidic, fruity, sparkling, and slightly alcoholic fermented beverage produced with water kefir grains, the latter consisting of polysaccharides and micro-organisms. The micro-organisms involved in water kefir fermentation comprise yeast, lactic acid bacteria, bifidobacteria, and acetic acid bacteria. Some strains of micro-organisms in water kefir might possess probiotic activity. Also, water kefir is a beverage with relatively low sugar content, providing an interesting alternative to sugary soft drinks. To be able to exploit water kefir for its probiotic potential or as a low-sugar soft-drink, in-depth research is needed to unravel the species diversity and community dynamics of water kefir fermentation. In particular, substrate consumption and metabolite production in water kefir have not been studied until now.

Water kefir is a sour, alcoholic, and fruity fermented beverage of which the fermentation is started with water kefir grains. These water kefir grains consist of polysaccharide and contain the microorganisms responsible for the water kefir fermentation. In this work, a water kefir fermentation process was followed as a function of time during 192 h to unravel the community dynamics, the species diversity, and the kinetics of substrate consumption and metabolite production. The majority of the water kefir ecosystem was found to be present on the water kefir grains. The most important microbial species present were Lactobacillus casei / paracasei , Lactobacillus harbinensis , Lactobacillus hilgardii , Bifidobacterium psychraerophilum / crudilactis , Saccharomyces cerevisiae , and Dekkera bruxellensis . The microbial species diversities in the water kefir liquor and on the water kefir grains were similar and remained stable during the whole fermentation process. The major substrate, sucrose, was completely converted after 24 h of fermentation, which coincided with the production of the major part of the water kefir grain polysaccharide. The main metabolites of the fermentation were ethanol and lactic acid. Glycerol, acetic acid, and mannitol were produced in low concentrations. The major part of these metabolites was produced during the first 72 h of fermentation, during which the pH decreased from 4.26 to 3.45. The most prevalent volatile aroma compounds were ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl octanoate, and ethyl decanoate, which might be of significance with respect to the aroma of the end product.