-
Frontiers in Microbiology 2022is the dominant taxon and cellulose-producing bacteria in the Kombucha Microbial Community (KMC). This is the first study to isolate the genome from a reactivated...
is the dominant taxon and cellulose-producing bacteria in the Kombucha Microbial Community (KMC). This is the first study to isolate the genome from a reactivated space-exposed KMC sample and comprehensively characterize it. The space-exposed genome was compared with the Earth-based reference genome to understand the genome stability of under extraterrestrial conditions during a long time. Our results suggest that the genomes of IMBG180 (ground sample) and IMBG185 (space-exposed) are remarkably similar in topology, genomic islands, transposases, prion-like proteins, and number of plasmids and CRISPR-Cas cassettes. Nonetheless, there was a difference in the length of plasmids and the location of genes. A small difference was observed in the number of protein coding genes. Despite these differences, they do not affect any genetic metabolic profile of the cellulose synthesis, nitrogen-fixation, hopanoid lipids biosynthesis, and stress-related pathways. Minor changes are only observed in central carbohydrate and energy metabolism pathways gene numbers or sequence completeness. Altogether, these findings suggest that maintains its genome stability and functionality in KMC exposed to the space environment most probably due to the protective role of the KMC biofilm. Furthermore, due to its unaffected metabolic pathways, this bacterial species may also retain some promising potential for space applications.
PubMed: 35369445
DOI: 10.3389/fmicb.2022.782175 -
International Journal of Biological... May 2022The versatility and unique properties of bacterial cellulose (BC) motivate research into enhancing its synthesis. Here a silicone polyether surfactant (SPS) was...
The versatility and unique properties of bacterial cellulose (BC) motivate research into enhancing its synthesis. Here a silicone polyether surfactant (SPS) was synthesized and tested as a non-nutritional additive to the cultivation media of Komagataeibacter xylinus. The addition of SPS to the Hestrin-Schramm (HS) medium resulted in a concentration-dependent decrease in surface tension from 59.57 ± 0.37 mN/m to 30.05 ± 0.41 mN/m (for 0.1% addition) that was correlated with an increased yield of BC, up to 37% wet mass for surfactant concentration close to its critical micelle concentration (0.008%). Physicochemical characterization of bacterial cellulose obtained in presence of SPS, showed that surfactant is not incorporated into BC structure and has a moderate effect on its crystallinity, thermal stability. Moreover, the water holding capacity was enhanced by over 40%. Importantly, obtained BC did not affect L929 murine fibroblast cell viability. We conclude that SPS provides an eco-friendly approach to increasing BC yield in static culture, enabling more widespread industrial and biomedical applications.
Topics: Animals; Bacteria; Cellulose; Culture Media; Gluconacetobacter xylinus; Mice; Silicones; Surface-Active Agents; Water
PubMed: 35337915
DOI: 10.1016/j.ijbiomac.2022.03.124 -
Microorganisms Feb 2022Bacterial cellulose (BC), a biopolymer, is synthesized by BC-producing bacteria. Almost all producing strains are classified in the family . In this study, bacterial...
Bacterial cellulose (BC), a biopolymer, is synthesized by BC-producing bacteria. Almost all producing strains are classified in the family . In this study, bacterial strain P285 was isolated from contaminated honey wine in a honey factory in northern Thailand. Based on 16S rRNA gene sequence identification, the strain P285 revealed 99.8% identity with LMG 1529 . P285 produced the maximum BC production at 20-30 °C and an initial media pH of 9.0. The highest BC production in modified mineral salt medium (MSM) was exhibited when glucose (16%, /) and yeast extract (3.2%, /) were applied as carbon and nitrogen sources, respectively. When sugarcane (8-16%, /) or honey (ratio of honey to water = 1: 4) supplemented with yeast extract was used, the BC production was greater. The characterization of BC synthesized by P285 was undertaken using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectrometry. Meanwhile, X-ray diffraction results confirmed the presence of crystalline cellulose (2θ = 18.330, 21.390 and 22.640°). The maximum temperature of BC degradation was observed at 314 °C. Tensile properties analysis of hydrated and dried BC showed breaking strength of 1.49 and 0.66 MPa, respectively. These results demonstrated that P285 has a high potential for BC production especially when grown in high initial media pH. Therefore, the strain would be suitable as an agent to make BC, the value-added product in the related factories.
PubMed: 35336103
DOI: 10.3390/microorganisms10030528 -
International Journal of Molecular... Mar 2022This article presents a comparative analysis of bacterial cellulose membranes synthesized by several strains of the genus in terms of their specific physical,...
This article presents a comparative analysis of bacterial cellulose membranes synthesized by several strains of the genus in terms of their specific physical, physico-chemical, and mechanical properties. Herein, the aim was to choose the most suitable microorganisms producing cellulosic materials with the greatest potential for the fabrication of bio-inspired nanocomposites. The selection was based on three main steps, starting from the evaluation of BNC biosynthetic efficiency with and without the addition of ethanol, followed by the assessment of mechanical breaking strength, and the physical parameters (compactness, structural integrity, appearance, and thickness) of the obtained biological materials. Ultimately, based on the performed screening procedure, three efficiently growing strains ( H3 (6Et), K4 (8Et), and sp. isolated from balsamic vinegar (12Et)) were chosen for further modifications, enabling additional cellulose functionalization. Here, supplementation of the growth medium with five representative polymeric compounds (citrus/apple pectin, wheat starch, polyvinyl alcohol, polyethylene glycol) led to significant changes in BNC properties, especially dye loading abilities, mechanical strength, and water adsorption/retention capacities. The resulting nanocomposites can be potentially useful in various fields of medicine and industry, and in the future, they may become a practical and cost-effective competitor against commercial biomaterials currently available on the market.
Topics: Acetic Acid; Acetobacteraceae; Cellulose; Culture Media
PubMed: 35328811
DOI: 10.3390/ijms23063391 -
Applied and Environmental Microbiology Apr 2022Cellulose is the most abundant biopolymer on earth and offers versatile applicability in biotechnology. Bacterial cellulose, especially, is an attractive material...
Cellulose is the most abundant biopolymer on earth and offers versatile applicability in biotechnology. Bacterial cellulose, especially, is an attractive material because it represents pure microcrystalline cellulose. The cellulose synthase complex of acetic acid bacteria serves as a model for general studies on (bacterial) cellulose synthesis. The genome of Komagataeibacter hansenii ATCC 23769 encodes three cellulose synthase (CS) operons of different sizes and gene compositions. This implies the question of which role each of the three CS-encoding operons, , , and , plays in overall cellulose synthesis. Therefore, we constructed markerless deletions in ATCC 23769, yielding mutant strains that expressed only one of the three CSs. Apparently, BcsAB1 is the only CS that produces fibers of crystalline cellulose. The markerless deletion of resulted in a nonfiber phenotype in scanning electron microscopy analysis. Expression of the other CSs resulted in a different, nonfibrous extracellular polymeric substance (nfEPS) structure wrapping the cells, which is proposed to contain acetylated cellulose. Transcription analysis revealed that all CSs were expressed continuously and that showed a higher transcription level than . Moreover, we were able to link the expression of diguanylate cyclase B () to cellulose production. Acetic acid bacteria form a massive biofilm called "mother of vinegar," which is built of cellulose fibers. Bacterial cellulose is an appealing biomaterial with manifold applications in biomedicine and biotechnology. Because most cellulose-producing acetic acid bacteria express several cellulose synthase operons, a deeper understanding of their contribution to the synthesis of modified forms of cellulose fibers within a natural biofilm is of special interest. For the first time, we were able to identify the contribution of each of the three cellulose synthases to cellulose formation in Komagataeibacter hansenii ATCC 23769 after a chromosomal clean deletion. Moreover, we were able to depict their roles in spatial composition of the biofilm. These findings might be applicable in the future for naturally modified biomaterials with novel properties.
Topics: Acetates; Acetobacteraceae; Cellulose; Extracellular Polymeric Substance Matrix; Operon
PubMed: 35319232
DOI: 10.1128/aem.02460-21 -
Microbial Cell Factories Mar 2022D-Xylonic acid is a versatile platform chemical with broad potential applications as a water reducer and disperser for cement and as a precursor for 1,4-butanediol and...
BACKGROUND
D-Xylonic acid is a versatile platform chemical with broad potential applications as a water reducer and disperser for cement and as a precursor for 1,4-butanediol and 1,2,4-tributantriol. Microbial production of D-xylonic acid with bacteria such as Gluconobacter oxydans from inexpensive lignocellulosic feedstock is generally regarded as one of the most promising and cost-effective methods for industrial production. However, high substrate concentrations and hydrolysate inhibitors reduce xylonic acid productivity.
RESULTS
The D-xylonic acid productivity of G. oxydans DSM2003 was improved by overexpressing the mGDH gene, which encodes membrane-bound glucose dehydrogenase. Using the mutated plasmids based on pBBR1MCS-5 in our previous work, the recombinant strain G. oxydans/pBBR-R3510-mGDH was obtained with a significant improvement in D-xylonic acid production and a strengthened tolerance to hydrolysate inhibitors. The fed-batch biotransformation of D-xylose by this recombinant strain reached a high titer (588.7 g/L), yield (99.4%), and volumetric productivity (8.66 g/L/h). Moreover, up to 246.4 g/L D-xylonic acid was produced directly from corn stover hydrolysate without detoxification at a yield of 98.9% and volumetric productivity of 11.2 g/L/h. In addition, G. oxydans/pBBR-R3510-mGDH exhibited a strong tolerance to typical inhibitors, i.e., formic acid, furfural, and 5-hydroxymethylfurfural.
CONCLUSION
Through overexpressing mgdh in G. oxydans, we obtained the recombinant strain G. oxydans/pBBR-R3510-mGDH, and it was capable of efficiently producing xylonic acid from corn stover hydrolysate under high inhibitor concentrations. The high D-xylonic acid productivity of G. oxydans/pBBR-R3510-mGDH made it an attractive choice for biotechnological production.
Topics: Fermentation; Gluconobacter oxydans; Xylose; Zea mays
PubMed: 35264166
DOI: 10.1186/s12934-022-01763-y -
MicrobiologyOpen Feb 2022Electronic scraps (e-scraps) represent an attractive raw material to mine demanded metals, as well as rare earth elements (REEs). A sequential microbial-mediated process...
Electronic scraps (e-scraps) represent an attractive raw material to mine demanded metals, as well as rare earth elements (REEs). A sequential microbial-mediated process developed in two steps was examined to recover multiple elements. First, we made use of an acidophilic bacteria consortium, mainly composed of Acidiphilium multivorum and Leptospidillum ferriphilum, isolated from acid mine drainages. The consortium was inoculated in a dissolution of e-scraps powder and cultured for 15 days. Forty-five elements were analyzed in the liquid phase over time, including silver, gold, and 15 REEs. The bioleaching efficiencies of the consortium were >99% for Cu, Co, Al, and Zn, 53% for Cd, and around 10% for Cr and Li on Day 7. The second step consisted of a microalgae-mediated uptake from e-scraps leachate. The strains used were two acidophilic extremotolerant microalgae, Euglena sp. (EugVP) and Chlamydomonas sp. (ChlSG) strains, isolated from the same extreme environment. Up to 7.3, 4.1, 1.3, and 0.7 µg by wet biomass (WB) of Zn, Al, Cu, and Mn, respectively, were uptaken by ChlSG biomass in 12 days, presenting higher efficiency than EugVP. Concerning REEs, ChlSG biouptake 14.9, 20.3, 13.7, 8.3 ng of Gd, Pr, Ce, La per WB. Meanwhile, EugVP captured 1.1, 1.5, 1.4, and 7.5, respectively. This paper shows the potential of a microbial sequential process to revalorize e-scraps and recover metals and REEs, harnessing extremotolerant microorganisms.
Topics: Acidiphilium; Bacteria; High-Throughput Nucleotide Sequencing; Industrial Waste; Metals; Microscopy, Electron, Scanning; Mining; Recycling
PubMed: 35212477
DOI: 10.1002/mbo3.1265 -
Proceedings of the National Academy of... Feb 2022Bacteria are efficient colonizers of a wide range of secluded microhabitats, such as soil pores, skin follicles, or intestinal crypts. How the structural diversity of...
Bacteria are efficient colonizers of a wide range of secluded microhabitats, such as soil pores, skin follicles, or intestinal crypts. How the structural diversity of these habitats modulates microbial self-organization remains poorly understood, in part because of the difficulty to precisely manipulate the physical structure of microbial environments. Using a microfluidic device to grow bacteria in crypt-like incubation chambers of systematically varied lengths, we show that small variations in the physical structure of the microhabitat can drastically alter bacterial colonization success and resistance against invaders. Small crypts are uncolonizable; intermediately sized crypts can stably support dilute populations, while beyond a second critical length scale, populations phase separate into a dilute region and a jammed region. The jammed state is characterized by extreme colonization resistance, even if the resident strain is suppressed by an antibiotic. Combined with a flexible biophysical model, we demonstrate that colonization resistance and associated priority effects can be explained by a crowding-induced phase transition, which results from a competition between proliferation and density-dependent cell leakage. The emerging sensitivity to scale underscores the need to control for scale in microbial ecology experiments. Systematic flow-adjustable length-scale variations may serve as a promising strategy to elucidate further scale-sensitive tipping points and to rationally modulate the stability and resilience of microbial colonizers.
Topics: Acetobacter; Anti-Bacterial Agents; Bacteriological Techniques; Drug Resistance, Bacterial; Lab-On-A-Chip Devices; Tetracycline
PubMed: 35145031
DOI: 10.1073/pnas.2115496119 -
Research in Microbiology 2022Cadmium (Cd) is a heavy metal used as raw material for several fertilizers and pesticides. The increase of Cd concentration in soils has been observed in cultivated...
Cadmium (Cd) is a heavy metal used as raw material for several fertilizers and pesticides. The increase of Cd concentration in soils has been observed in cultivated areas, affecting animals, plants, and microorganisms. Gluconacetobacter diazotrophicus is a plant growth-promoting bacterium able to survive under adverse environmental conditions. Here, we investigated key mechanisms involved with the resistance of G. diazotrophicus to Cd. Proteomic analyses revealed that the main pathways regulated in response to Cd are nutrient uptake, multidrug efflux pumps, response to oxidative stress, and protein quality control system. Extracytoplasmic proteins related to multidrug efflux pumps were up-accumulated, while several proteins related to nutrients uptake were down-accumulated. The relevance of these pathways for bacterial resistance to Cd was investigated by reverse genetic analysis using mutants defective for nutrient uptake (tdbr, ompW, and oprB), multidrug efflux (czcC), response to oxidative stress (ggt), and protein quality control system (clpX). Our data demonstrated the essential role of the tdbr and czcC genes for resistance to Cd in G. diazotrophicus. These results contribute to a better understanding of the resistance mechanisms to Cd in G. diazotrophicus, shedding light on responses associated with extracytoplasmic compartments.
Topics: Cadmium; Gluconacetobacter; Plants; Proteomics
PubMed: 35104604
DOI: 10.1016/j.resmic.2022.103922 -
Journal of Bacteriology Mar 2022Acetic acid bacteria catalyze the two-step oxidation of ethanol to acetic acid using the membrane-bound enzymes pyrroloquinoline quinone-dependent alcohol dehydrogenase...
Acetic acid bacteria catalyze the two-step oxidation of ethanol to acetic acid using the membrane-bound enzymes pyrroloquinoline quinone-dependent alcohol dehydrogenase and molybdopterin-dependent aldehyde dehydrogenase (ALDH). Although the reducing equivalents from the substrate are transferred to ubiquinone in the membrane, intramolecular electron transport in ALDH is not understood. Here, we purified the AldFGH complex, the membrane-bound ALDH that is physiologically relevant to acetic acid fermentation in Gluconacetobacter diazotrophicus strain PAL5. The purified AldFGH complex showed acetaldehyde:ubiquinone (Q) oxidoreductase activity. -type cytochromes of the AldFGH complex (in the AldF subunit) were reduced by acetaldehyde. Next, we genetically dissected the AldFGH complex into AldGH and AldF units and reconstituted them. The AldGH subcomplex showed acetaldehyde:ferricyanide oxidoreductase activity but not Q reductase activity. The ALDH activity of AldGH was not found in membranes but was found in the soluble fraction of the recombinant strain, suggesting that the AldF subunit is responsible for membrane binding of the AldFGH complex. The absorption spectra of the purified AldGH subcomplex suggested the presence of an [Fe-S] cluster, which can be reduced by acetaldehyde. The AldFGH complex reconstituted from the AldGH subcomplex and AldF showed Q reductase activity. We propose a model in which electrons from the substrate are abstracted by a molybdopterin in the AldH subunit and transferred to the [Fe-S] cluster(s) in the AldG subunit, followed by electron transport to -type cytochrome centers in the AldF subunit, which is the site of ubiquinone reduction in the membrane. Two membrane-bound enzymes of acetic acid bacteria, pyrroloquinoline quinone-dependent alcohol dehydrogenase and molybdopterin-dependent aldehyde dehydrogenase (ALDH), are responsible for vinegar production. Upon the oxidation of acetaldehyde, ALDH reduces ubiquinone in the cytoplasmic membrane. ALDH is an enzyme complex of three subunits. Here, we tried to understand how ALDH works by using a classical biochemical approach and genetic engineering to dissect the enzyme complex into soluble and membrane-bound parts. The soluble part had limited activity and did not reduce ubiquinone. However, the enzyme complex reconstituted from the soluble and membrane-bound parts showed ubiquinone reduction activity. The proposed working model of ALDH provides a better understanding of how the enzyme works in the vinegar fermentation process.
Topics: Acetaldehyde; Acetic Acid; Alcohol Dehydrogenase; Aldehyde Dehydrogenase; Aldehydes; Cytochromes; Electron Transport; Gluconacetobacter; PQQ Cofactor; Ubiquinone
PubMed: 35072518
DOI: 10.1128/jb.00558-21