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Sheng Wu Gong Cheng Xue Bao = Chinese... Jun 2024Bacterial cellulose (BC) is a biopolymer synthesized by bacteria, which possess excellent characteristics such as high water holding capacity, high crystallinity, and...
Bacterial cellulose (BC) is a biopolymer synthesized by bacteria, which possess excellent characteristics such as high water holding capacity, high crystallinity, and high purity. It is widely used in food, medical, cosmetics, and functional films. is a model strain used in BC synthesis research. In bacteria, motility-related genes are associated with BC synthesis, whereas in CGMCC 2955, the functions of motility-related genes and their effects on BC synthesis are not known. To address this gap, we used the λ Red recombinant system to individually knock out , , and respectively, and constructed the knockout strains . -Δ, . -Δ, and . -Δ. Additionally, both and were disrupted to construct the . -Δ mutant. The results demonstrated that knockout strain . -Δ exhibited the highest BC yield, reaching (5.05±0.26) g/L, which represented an increase of approximately 24% compared to wild-type strains. Furthermore, the BC synthesized by this strain exhibited the lowest porosity, 54.35%, and displayed superior mechanical properties with a Young's modulus of up to 5.21 GPa. As knocking out and genes in . CGMCC 2955 did not reduce BC yield; instead, it promoted BC synthesis. Consequently, this research further deepened our understanding of the relationship between motility and BC synthesis in acetic acid bacteria. The knockouts of and genes resulted in reduced BC porosity and improved mechanical properties, provides a reference for BC synthesis and membrane structure regulation modification.
Topics: Cellulose; Acetobacteraceae; Gene Knockout Techniques; Bacterial Proteins; Gluconacetobacter xylinus; Genes, Bacterial
PubMed: 38914496
DOI: 10.13345/j.cjb.230684 -
Biotechnology Journal Jun 2024Industrial production of bacterial cellulose (BC) remains challenging due to significant production costs, including the choice of appropriate growth media. This...
Industrial production of bacterial cellulose (BC) remains challenging due to significant production costs, including the choice of appropriate growth media. This research focuses on optimization of cheese whey (CW) based media for enhanced production of BC. Two modifications were made for CW medium for BC production with Komagataeibacter rhaeticus MSCL 1463. BC production in a medium of enzymatically hydrolyzed CW (final concentration of monosaccharides: glucose 0.13 g L, galactose 1.24 g L) was significantly enhanced, achieving a yield of 4.95 ± 0.25 g L, which markedly surpasses the yields obtained with the standard Hestrin-Schramm (HS) medium containing 20 g L glucose and acid-hydrolyzed CW (final concentration of monosaccharides: glucose 1.15 g L, galactose 2.01 g L), which yielded 3.29 ± 0.12 g L and 1.01 ± 0.14 g L, respectively. We explored the synergistic effects of combining CW with various agricultural by-products (corn steep liquor (CSL), apple juice, and sugar beet molasses). Notably, the supplementation with 15% corn steep liquor significantly enhanced BC productivity, achieving 6.97 ± 0.17 g L. A comprehensive analysis of the BC's physical and mechanical properties indicated significant alterations in fiber diameter (62-167 nm), crystallinity index (71.1-85.9%), and specific strength (35-82 MPa × cm g), as well as changes in the density (1.1-1.4 g cm). Hydrolyzed CW medium supplemented by CSL could be used for effective production of BC.
Topics: Cellulose; Whey; Cheese; Culture Media; Hydrolysis; Acetobacteraceae; Fermentation; Zea mays; Glucose; Fruit and Vegetable Juices
PubMed: 38896375
DOI: 10.1002/biot.202300529 -
Water Research Aug 2024This study explored the potential of sand biofiltration for tertiary treatment of real refinery wastewater. The biofilter (2 cm (I.D.) x 15 cm (L)) operated on secondary...
This study explored the potential of sand biofiltration for tertiary treatment of real refinery wastewater. The biofilter (2 cm (I.D.) x 15 cm (L)) operated on secondary treated refinery wastewater at flow rate of 1 mL/min had empty bed contact time (EBCT) of 47.12 min for one circulation. Maximum reduction in COD after 4, 8 and 12 times recirculation was 25 %, 52 % and 56 %; while the TOC reduction was 33 %, 43 % and 51 %, respectively, after biofilm development over 30 days. Quantification using two dimensional gas chromatography - time of flight mass spectrometry (GCxGC-TOF MS) revealed that several of the identified target compounds could not be detected in the wastewater after 12 recirculations. After 8 times recirculation, most of the compounds showed very high removal efficiency. For biofiltration over the flow rate range 2-10 mL/min, the reduction in COD and NH-N ranged from 62-73 % and 78-86 %, respectively, after 8 times recirculation. The nitrite concentration first increased and subsequently decreased, while the nitrate concentration continuously increased with increase in the number of recirculations. Solid phase micro-extraction (SPME) analysis of the aqueous phase using GCxGC-TOF MS and a semi-quantitative approach indicated that the removal of predominant classes of compounds was greater than 95 % after 8 times recirculation, with maximum reduction occurring in the first pass through the biofilter. Assimilable organic carbon (AOC) reduction was 98 % after 8 times recirculation. Metagenomic analysis revealed that Proteobacteria was the most dominant phylum in the biofilter. Many known polynuclear aromatic hydrocarbon (PAH) degraders, such as Sphingomonadales, Burkholderiales, Rhodobacterales and Rhodospirillales, were found in the biofilter leading to high removal efficiency of hazardous organic pollutants.
Topics: Filtration; Wastewater; Water Pollutants, Chemical; Waste Disposal, Fluid; Silicon Dioxide; Organic Chemicals; Water Purification; Biofilms
PubMed: 38870887
DOI: 10.1016/j.watres.2024.121874 -
PloS One 2024Our previous studies indicate the abundant and diverse presence of yet-to-be-cultured microorganisms in the micropore-filtered fractions of various environmental...
Our previous studies indicate the abundant and diverse presence of yet-to-be-cultured microorganisms in the micropore-filtered fractions of various environmental samples. Here, we isolated a novel bacterium (designated as strain TMPK1T) from a 0.45-μm-filtered soil suspension by using a gel-filled microwell array device comprising 900 microwells and characterized its phylogenetic and physiological features. This strain showed low 16S rRNA gene sequence identities (<91%) and low average nucleotide identity values (<70%) to the closest validly described species, and belonged to a novel-family-level lineage within the order Rhodospirillales of Alphaproteobacteria. Strain TMPK1T exhibited small cell sizes (0.08-0.23 μm3) and had a high cyclopropane fatty acid content (>13%), and these characteristics were differentiated from other Rhodospirillales bacteria. A comprehensive habitability search using amplicon datasets suggested that TMPK1T and its close relatives are mainly distributed in soil and plant-associated environments. Based on these results, we propose that strain TMPK1T represents a novel genus and species named Roseiterribacter gracilis gen. nov., sp. nov. (JCM 34627T = KCTC 82790T). We also propose Roseiterribacteraceae fam. nov. to accommodate the genus Roseiterribacter.
Topics: Soil Microbiology; Phylogeny; RNA, Ribosomal, 16S; Fatty Acids; Alphaproteobacteria; DNA, Bacterial
PubMed: 38857291
DOI: 10.1371/journal.pone.0304366 -
Brazilian Journal of Biology = Revista... 2024Agricultural management using technologies that help farmers increase productivity and reduce production costs must be promoted to ensure agricultural sustainability....
Agricultural management using technologies that help farmers increase productivity and reduce production costs must be promoted to ensure agricultural sustainability. The objective of the study was to achieve the pH effect of growth solution, chemical treatment, use of osmoprotector additive and mineral nitrate presence, on the activity of growth promoting bacteria, Azospirillum brasilense, and its effects on the physiological quality of seeds and wheat seedling growth. The first experiment evaluated the physiological quality of seeds and the second experiment was divided into four, evaluating the growth of wheat seedling in a hydroponic system. The experiments were prolonged in a very randomized design, with four replications. The physiological quality of the seeds was evaluated by germination tests, first germination count, length of the shoot and root and dry mass of the shoot and root. Initial growth was evaluated by quantifying the dry mass of the leaf shoot and root and the root system intervals. The pH of the solution and the presence of nitrogen did not influence the effects of inoculation of the A. brasilense bacteria. With the use of chemical treatment and osmoprotective additive, A. brasilense had no effect on the growth of wheat seedlings.
Topics: Triticum; Azospirillum brasilense; Seedlings; Culture Media; Germination; Hydrogen-Ion Concentration
PubMed: 38836802
DOI: 10.1590/1519-6984.281973 -
Harmful Algae May 2024Toxic cyanobacterial blooms present a substantial risk to public health due to the production of secondary metabolites, notably microcystins (MCs). Microcystin-LR...
Toxic cyanobacterial blooms present a substantial risk to public health due to the production of secondary metabolites, notably microcystins (MCs). Microcystin-LR (MC-LR) is the most prevalent and toxic variant in freshwater. MCs resist conventional water treatment methods, persistently impacting water quality. This study focused on an oligohaline shallow lagoon historically affected by MC-producing cyanobacteria, aiming to identify bacteria capable of degrading MC and investigating the influence of environmental factors on this process. While isolated strains did not exhibit MC degradation, microbial assemblages directly sourced from lagoon water removed MC-LR within seven days at 25 ºC and pH 8.0. The associated bacterial community demonstrated an increased abundance of bacterial taxa assigned to Methylophilales, and also Rhodospirillales and Rhodocyclales to a lesser extent. However, elevated atmospheric temperatures (45 ºC) and acidification (pH 5.0 and 3.0) hindered MC-LR removal, indicating that extreme environmental changes could contribute to prolonged MC persistence in the water column. This study highlights the importance of considering environmental conditions in order to develop strategies to mitigate cyanotoxin contamination in aquatic ecosystems.
Topics: Microcystins; Bacteria; Cyanobacteria; Microbiota; Seawater; Plankton; Hydrogen-Ion Concentration
PubMed: 38830712
DOI: 10.1016/j.hal.2024.102646 -
Journal of Bacteriology Jun 2024Magnetotactic bacteria are a diverse group of microbes that use magnetic particles housed within intracellular lipid-bounded magnetosome organelles to guide navigation...
Magnetotactic bacteria are a diverse group of microbes that use magnetic particles housed within intracellular lipid-bounded magnetosome organelles to guide navigation along geomagnetic fields. The development of magnetosomes and their magnetic crystals in AMB-1 requires the coordinated action of numerous proteins. Most proteins are thought to localize to magnetosomes during the initial stages of organelle biogenesis, regardless of environmental conditions. However, the magnetite-shaping protein Mms6 is only found in magnetosomes that contain magnetic particles, suggesting that it might conditionally localize after the formation of magnetosome membranes. The mechanisms for this unusual mode of localization to magnetosomes are unclear. Here, using pulse-chase labeling, we show that Mms6 translated under non-biomineralization conditions translocates to pre-formed magnetosomes when cells are shifted to biomineralizing conditions. Genes essential for magnetite production, namely and are necessary for Mms6 localization, whereas inhibits Mms6 localization. MamD localization was also investigated and found to be controlled by similar cellular factors. The membrane localization of Mms6 is dependent on a glycine-leucine repeat region, while the N-terminal domain of Mms6 is necessary for retention in the cytosol and impacts conditional localization to magnetosomes. The N-terminal domain is also sufficient to impart conditional magnetosome localization to MmsF, altering its native constitutive magnetosome localization. Our work illuminates an alternative mode of protein localization to magnetosomes in which Mms6 and MamD are excluded from magnetosomes by MamN until biomineralization initiates, whereupon they translocate into magnetosome membranes to control the development of growing magnetite crystals.IMPORTANCEMagnetotactic bacteria (MTB) are a diverse group of bacteria that form magnetic nanoparticles surrounded by membranous organelles. MTB are widespread and serve as a model for bacterial organelle formation and biomineralization. Magnetosomes require a specific cohort of proteins to enable magnetite formation, but how those proteins are localized to magnetosome membranes is unclear. Here, we investigate protein localization using pulse-chase microscopy and find a system of protein coordination dependent on biomineralization-permissible conditions. In addition, our findings highlight a protein domain that alters the localization behavior of magnetosome proteins. Utilization of this protein domain may provide a synthetic route for conditional functionalization of magnetosomes for biotechnological applications.
Topics: Magnetospirillum; Magnetosomes; Bacterial Proteins; Gene Expression Regulation, Bacterial; Protein Transport
PubMed: 38819153
DOI: 10.1128/jb.00008-24 -
Biochimica Et Biophysica Acta.... Aug 2024Purple phototrophic bacteria possess light-harvesting 1 and reaction center (LH1-RC) core complexes that play a key role in converting solar energy to chemical energy....
Purple phototrophic bacteria possess light-harvesting 1 and reaction center (LH1-RC) core complexes that play a key role in converting solar energy to chemical energy. High-resolution structures of LH1-RC and RC complexes have been intensively studied and have yielded critical insight into the architecture and interactions of their proteins, pigments, and cofactors. Nevertheless, a detailed picture of the structure and assembly of LH1-only complexes is lacking due to the intimate association between LH1 and the RC. To study the intrinsic properties and structure of an LH1-only complex, a genetic system was constructed to express the Thermochromatium (Tch.) tepidum LH1 complex heterologously in a modified Rhodospirillum rubrum mutant strain. The heterologously expressed Tch. tepidum LH1 complex was isolated in a pure form free of the RC and exhibited the characteristic absorption properties of Tch. tepidum. Cryo-EM structures of the LH1-only complexes revealed a closed circular ring consisting of either 14 or 15 αβ-subunits, making it the smallest completely closed LH1 complex discovered thus far. Surprisingly, the Tch. tepidum LH1-only complex displayed even higher thermostability than that of the native LH1-RC complex. These results reveal previously unsuspected plasticity of the LH1 complex, provide new insights into the structure and assembly of the LH1-RC complex, and show how molecular genetics can be exploited to study membrane proteins from phototrophic organisms whose genetic manipulation is not yet possible.
Topics: Light-Harvesting Protein Complexes; Chromatiaceae; Bacterial Proteins; Rhodospirillum rubrum
PubMed: 38806091
DOI: 10.1016/j.bbabio.2024.149050 -
Biochemical and Biophysical Research... Aug 2024Azospirillum brasilense is a non-photosynthetic α-Proteobacteria, belongs to the family of Rhodospirillaceae and produces carotenoids to protect itself from...
Azospirillum brasilense is a non-photosynthetic α-Proteobacteria, belongs to the family of Rhodospirillaceae and produces carotenoids to protect itself from photooxidative stress. In this study, we have used Resonance Raman Spectra to show similarity of bacterioruberins of Halobacterium salinarum to that of A. brasilense Cd. To navigate the role of genes involved in carotenoid biosynthesis, we used mutational analysis to inactivate putative genes predicted to be involved in carotenoid biosynthesis in A. brasilense Cd. We have shown that HpnCED enzymes are involved in the biosynthesis of squalene (C30), which is required for the synthesis of carotenoids in A. brasilense Cd. We also found that CrtI and CrtP desaturases were involved in the transformation of colorless squalene into the pink-pigmented carotenoids. This study elucidates role of some genes which constitute very pivotal role in biosynthetic pathway of carotenoid in A. brasilense Cd.
Topics: Carotenoids; Azospirillum brasilense; Squalene; Bacterial Proteins; Biosynthetic Pathways; Spectrum Analysis, Raman
PubMed: 38795456
DOI: 10.1016/j.bbrc.2024.150154 -
Medicine May 2024Patients with intracranial hemorrhage (ICH) usually have an imbalance in the gut microbiota (GM); however, whether this is a causal correlation remains unclear. This...
Patients with intracranial hemorrhage (ICH) usually have an imbalance in the gut microbiota (GM); however, whether this is a causal correlation remains unclear. This study used summary data from an open genome-wide association study to conduct double-sample Mendelian randomization (MR) to test the causal correlation between GM and ICH. First, we used a cutoff value of P < 10E-5 to select single nucleotide polymorphisms critical for each GM. Inverse variance weighted, weighted median, and MR-PRESSO methods were used to evaluate the strength of this causal association. Finally, functional maps and annotations from genome-wide association studies were used to determine the biological functions of the genes. MR analysis revealed that Rikenellaceae RC9 gut group was significantly positively correlated with ICH risk. For every unit increase in Rikenellaceae RC9 gut group, the relative risk of ICH increased by 34.4%(P = 4.62E-04). Rhodospirillales, Terrisporobacter, Veillonellaceae, Coprococcus 3, unknown genus, Alphaproteobacteria, and Allisonella groups were negatively correlated with the risk of ICH, while Anaerofilum, Eubacteriumbrachy group, Clostridia, Howardella, and Romboutsia were negatively correlated with the risk of ICH. Nonetheless, the specific role of single nucleotide polymorphisms gene enrichment requires further investigation. This study suggests the causal effect on ICH. The discovery of >10 GMs associated with ICH could be used to prevent and treat ICH.
Topics: Mendelian Randomization Analysis; Humans; Gastrointestinal Microbiome; Polymorphism, Single Nucleotide; Genome-Wide Association Study; Intracranial Hemorrhages
PubMed: 38788039
DOI: 10.1097/MD.0000000000038275