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1.
Int J Food Microbiol ; 418: 110719, 2024 Jun 16.
Article in English | MEDLINE | ID: mdl-38688186

ABSTRACT

Lactiplantibacillus paraplantarum P3 (L. paraplantarum P3) cell-free supernatant (CFS) with good antifungal effect was sprayed on fresh in-shell peanuts stored at 5 °C and 30 °C to explore its effect on the microorganisms and quality of fresh in-shell peanuts during storage process. Results showed that L. paraplantarum P3 CFS effectively maintained good quality of fresh in-shell peanuts by not only reducing fungi amount and the mildew rate, but also improving the morphology, color and flavor. Besides, L. paraplantarum P3 CFS activated plant mitogen-activated protein kinase signaling pathway and plant hormone signaling pathway to produce more ethylene, gibberellin regulatory proteins and other substances to enhance plant resistance to pathogenic microorganisms. L. paraplantarum P3 CFS could also induce the biosynthesis of glycerophospholipid and arginine to increase the stress resistance of fresh peanuts. This study provides research data for the application of L. paraplantarum P3 CFS in the preservation and antimildew of fresh in-shell peanuts.


Subject(s)
Arachis , Arachis/microbiology , Food Storage , Plant Diseases/microbiology , Plant Diseases/prevention & control , Food Preservation/methods , Fungi/drug effects , Fungi/metabolism , Food Microbiology
2.
Foods ; 13(5)2024 Feb 28.
Article in English | MEDLINE | ID: mdl-38472853

ABSTRACT

Proanthocyanidins are important compounds known for their antioxidant and radical scavenging properties, but they are highly sensitive to light, heat, oxygen, and pH. In our study, proanthocyanidin was encapsulated using sodium alginate and carboxymethyl cellulose to enhance controlled release, pH stability, metal ion tolerance, temperature resistance, time release, the microencapsulation of food additives stability, antioxidant capacity analysis, and the storage period tolerance of proanthocyanidin. Fourier transforms infrared (FTIR) analysis and full-wavelength UV scanning indicated the successful immobilization of proanthocyanidins into the polymeric microcapsules. The flowability and mechanical properties of the microcapsules were enhanced. Moreover, proanthocyanidin microcapsules exhibited higher thermal, pH, metal ion, time, and microencapsulation food additive stability. In addition, due to their high antioxidant properties, the proanthocyanidin microcapsules retained a greater amount of proanthocyanidin content during the gastric phase, and the proanthocyanidin was subsequently released in the intestinal phase for absorption. Thus, the study provided a systematic understanding of the antioxidant capabilities and stability of proanthocyanidin microcapsules, which is beneficial for developing preservation methods for food additives.

3.
Foods ; 13(3)2024 Feb 02.
Article in English | MEDLINE | ID: mdl-38338606

ABSTRACT

The study proposed to investigate the impacts of storage temperatures (15, 20, 25 °C) on the oxidative stability (peroxide value, carbonyl value, malondialdehyde content) and sensory attributes (pasting properties, cooked brown rice flavor) of high-moisture japonica brown rice. According to the findings, the peroxide value, the carbonyl value, and the malondialdehyde content of high-moisture japonica brown rice stored at a temperature of 15 °C exhibited consistently low levels, and the pasting properties were favorable. In addition, 22 out of 51 flavor volatiles were screened as key differential volatile flavor compounds in cooked brown rice via a combination of ANOVA and orthogonal projections to latent structures-discriminant analysis (OPLS-DA). Among them, 3-heptylacrolein had an aroma of fat and mushroom, and its contents were higher at 15 °C and 20 °C. These findings could serve as a valuable reference for storing high-moisture japonica brown rice under low temperature conditions as well as for investigating the flavor characteristics of cooked brown rice derived from this variety.

4.
J Stomatol Oral Maxillofac Surg ; 125(6): 101784, 2024 Jan 28.
Article in English | MEDLINE | ID: mdl-38286218

ABSTRACT

When anatomical landmarks are missing or obstructed by metal artefacts, it is challenging to accurately merge cone beam computed tomography (CBCT) and intraoral scanning (IOS) information, and the accuracy of the implant surgical guides would be compromised. This article describes a novel technical note using oral wound dressings and flowable resin as additional new radiopaque fiducial landmarks to design surgical guides for full-arch immediate implant placement. This technical note provided an accurate, convenient, and cost-effective option for the clinician.

5.
Int J Food Microbiol ; 411: 110552, 2024 Feb 02.
Article in English | MEDLINE | ID: mdl-38159444

ABSTRACT

Maize moldy and spoilage due to microbial growth is a significant challenge in grain storage. This study aimed to evaluate the effectiveness of a zinc oxide nanocomposite, ZnO@mSiO2, prepared in our previous research, in inhibiting mold growth and preserving maize cell quality. The results demonstrated that ZnO@mSiO2 could effectively inhibit the growth of dominant microorganism, Aspergillus flavus, Talaromyces variabilis, Penicillium citrinum and Fusarium graminearum, in maize storage. Aspergillus flavus was selected as the model fungus, ZnO@mSiO2 effectively disrupted fungal hyphae structure, leading to reduced hyphal mass and inhibited spore germination. The inhibitory effect of ZnO@mSiO2 on mold growth was concentration-dependent. However, the ZnO@mSiO2 at an appropriate concentration (not exceeding 3.0 g/kg) preserved the integrity of maize cell membranes and enhancing the antioxidant activity within maize cells. The findings highlight the potential of ZnO@mSiO2 as an effective protectant to inhibit mold growth and preserve maize quality during storage.


Subject(s)
Zinc Oxide , Zinc Oxide/pharmacology , Zea mays/microbiology , Aspergillus flavus , Fungi , Edible Grain
6.
Front Microbiol ; 14: 1258452, 2023.
Article in English | MEDLINE | ID: mdl-37901831

ABSTRACT

Motile bacteria take a competitive advantage in colonization of plant surfaces to establish beneficial associations that eventually support plant health. Plant exudates serve not only as primary growth substrates for bacteria but also as bacterial chemotaxis attractants. A number of plant-derived compounds and corresponding chemotaxis sensors have been documented, however, the sensors for methanol, one of the major volatile compounds released by plants, have not been identified. Methylobacterium species are ubiquitous plant surface-symbiotic, methylotrophic bacteria. A plant-growth promoting bacterium, M. aquaticum strain 22A exhibits chemotaxis toward methanol (methylotaxis). Its genome encodes 52 methyl-accepting chemotaxis proteins (MCPs), among which we identified three MCPs (methylotaxis proteins, MtpA, MtpB, and MtpC) responsible for methylotaxis. The triple gene mutant of the MCPs exhibited no methylotaxis, slower gathering to plant tissues, and less efficient colonization on plants than the wild type, suggesting that the methylotaxis mediates initiation of plant-Methylobacterium symbiosis and engages in proliferation on plants. To examine how these MCPs are operating methylotaxis, we generated multiple gene knockouts of the MCPs, and Ca2+-dependent MxaFI and lanthanide (Ln3+)-dependent XoxF methanol dehydrogenases (MDHs), whose expression is regulated by the presence of Ln3+. MtpA was found to be a cytosolic sensor that conducts formaldehyde taxis (formtaxis), as well as methylotaxis when MDHs generate formaldehyde. MtpB contained a dCache domain and exhibited differential cellular localization in response to La3+. MtpB expression was induced by La3+, and its activity required XoxF1. MtpC exhibited typical cell pole localization, required MxaFI activity, and was regulated under MxbDM that is also required for MxaF expression. Strain 22A methylotaxis is realized by three independent MCPs, two of which monitor methanol oxidation by Ln3+-regulated MDHs, and one of which monitors the common methanol oxidation product, formaldehyde. We propose that methanol metabolism-linked chemotaxis is the key factor for the efficient colonization of Methylobacterium on plants.

7.
Foods ; 12(20)2023 Oct 16.
Article in English | MEDLINE | ID: mdl-37893685

ABSTRACT

Grain is the basic material that guarantees human survival, and its security is inextricably linked to the sustainable development and future destiny of humanity [...].

8.
Toxins (Basel) ; 15(3)2023 03 16.
Article in English | MEDLINE | ID: mdl-36977117

ABSTRACT

The contamination of fermented feeds and foods with fungi and mycotoxins is a major food safety issue worldwide. Certain lactic acid bacteria (LAB), generally recognized as safe (GRAS) fermentation probiotics, are able to reduce microbial and mycotoxins contamination. In this study, Lactiplantibacillus (L.) plantarum Q1-2 and L. salivarius Q27-2 with antifungal properties were screened as inoculants for mixed fermenting feed, and the fermentation and nutritional qualities, microbial community, and mycotoxins of mixed fermented feed were analyzed at different fermentation periods (1, 3, 7, 15, and 30 days, respectively). The findings indicated that the utilization of Q1-2 and Q27-2 strains in fermenting feed led to a decrease in pH and an increase in lactic acid concentration and the proportion of Lactiplantibacillus, while effectively restraining the proliferation of undesirable microorganisms. In particular, Q1-2 reduced the relative abundance of fungi including Fusarium and Aspergillus. Compared to the control group, the Q1-2 and Q27-2 groups reduced aflatoxin B1 by 34.17% and 16.57%, and deoxynivalenol by up to 90.61% and 51.03%. In short, these two LAB inoculants could reduce the contents of aflatoxin B1 and deoxynivalenol to the limited content levels stipulated by the Chinese National Standard GB 13078-2017. These findings suggest that the LAB strains of Q1-2 and Q27-2 have potential applications in the feed industry for the mitigation of mycotoxin pollution, thereby enhancing the quality of animal feed.


Subject(s)
Lactobacillales , Mycotoxins , Animals , Mycotoxins/chemistry , Aflatoxin B1/analysis , Fungi , Animal Feed/analysis
9.
Food Chem ; 415: 135734, 2023 Jul 30.
Article in English | MEDLINE | ID: mdl-36848837

ABSTRACT

This research developed a novel, efficient and safe antimildew for peanut kernel postharvest storage. The antimildew, cinnamon-Litsea cubeba compound essential oil (CLCEO) microcapsule (CLCEOM), was synthesized with CLCEO as core materials and ß-cyclodextrin as wall materials. Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry analyses indicated that major antifungal compounds of CLCEO were encapsulated in the cavity of ß-cyclodextrin. The inhibition zone experiment showed that CLCEOM retained antifungal effect on Aspergillus spp. strains even after storage for 2 months at 4 â„ƒ. Besides, CLCEOM reduced total number of fungal colonies, relative abundance of Aspergillus spp., and aflatoxin B1 content of peanut kernels, and had positive effect on slowing down the increase in acid value of peanut oil without causing any adverse effect on the viability and sensory properties during storage process. Overall, CLCEOM presented good preservative effects on peanut kernels, providing evidence for its potential use as antimildew for peanut storage.


Subject(s)
Litsea , Oils, Volatile , Oils, Volatile/chemistry , Arachis , Litsea/chemistry , Cinnamomum zeylanicum , Antifungal Agents/pharmacology , Capsules , Aspergillus
10.
J Prosthet Dent ; 129(6): 835-839, 2023 Jun.
Article in English | MEDLINE | ID: mdl-34556334

ABSTRACT

Designing implant surgical guides for patients undergoing orthodontics merely by merging data imaging and communications in medicine (DICOM) files generated from cone beam computed tomography (CBCT) images and standard tessellation language (STL) files generated from surface scanners is challenging because of the inaccuracy caused by metal artifacts. The present technique describes a straightforward and effective method of fabricating a surgical guide with the aid of fiducial markers made from cotton swabs and flowable resin. The implant surgical guide is designed by using a software program after the superimposition of digital scan and CBCT data. This chairside technique provides an accurate, convenient, and cost-effective option for the clinician.


Subject(s)
Dental Implants , Orthodontic Brackets , Surgery, Computer-Assisted , Humans , Fiducial Markers , Imaging, Three-Dimensional , Dental Implantation, Endosseous/methods , Cone-Beam Computed Tomography/methods , Surgery, Computer-Assisted/methods , Computer-Aided Design
11.
Foods ; 12(23)2023 Nov 22.
Article in English | MEDLINE | ID: mdl-38231596

ABSTRACT

Low temperatures are an effective way of delaying grain rancidity and deterioration. However, little is known about the difference in quality changes in high-moisture japonica brown rice at different storage temperatures. In this study, the storage quality changes in japonica brown rice with a 15.50% moisture content stored at 15 °C, 20 °C, and 25 °C were investigated. In addition, an untargeted lipidomics analysis coupled with gas chromatography and mass spectrometry (GC-MS) was applied to analyze the volatile compounds and metabolite changes in the high-moisture japonica brown rice. The results showed that storage at 15 °C could well maintain the color and aroma stability of the brown rice and delay the increase in fatty acid value (FAV). The lipidomics results showed that storage at 15 °C delayed glycerolipid and sphingolipid metabolism and reduced glycerophospholipid catabolism in the brown rice. The low-temperature environment regulated these three metabolic pathways to maintain higher contents of triglycerides (TG), phosphatidylserine (PS), abd phosphatidylethanolamine (PE), and lower contents of diglycerides (DG), OAcyl-(gamma-hydroxy) FA (OAHFA), ceramides (Cer), and glycosylceramides (Hex1Cer) in the high-moisture japonica brown rice, which maintained the storage stability of the brown rice. Our results proposed the cryoprotection mechanism of postharvest brown rice from the perspective of volatile compounds and metabolite changes, providing a foothold for the further exploration of low-temperature storage as a safe and efficient cryoprotectant in the grain storage field.

12.
Foods ; 11(11)2022 May 28.
Article in English | MEDLINE | ID: mdl-35681336

ABSTRACT

The antifungal activity of cinnamon (Cinnamomum cassia Presl), litsea [Litsea cubeba (Lour.) Pers.], clove (Syzygium aromaticum L.), thyme (Thymus mongolicus Ronn.) and citronella (Cymbopogon winterianus Jowitt) essential oils (EOs) against the dominant fungi isolated from moldy peanuts was investigated in this research. Firstly, strain YQM was isolated and identified by morphological characterization and 18S rRNA gene sequence analysis to be Aspergillus flavus (A. flavus). Next, antifungal effects of single or mixed EOs on strain YQM were evaluated by the inhibition zone test. The cinnamon-litsea combined essential oil (CLCEO, Vcinnamon oil:Vlitsea oil = 3:5) displayed the best antifungal effect on strain YQM. The chemical composition of CLCEO was identified and quantified by gas chromatograph-mass spectrometry (GC-MS), and results revealed that the major components of CLCEO were cinnamaldehyde and citral. Finally, the effect of EOs on the microstructure of strain YQM mycelia was observed under scanning electron microscope (SEM). The mycelia exposed to cinnamon essential oil (CEO) and litsea essential oil (LEO) were partly deformed and collapsed, while the mycelia treated with CLCEO were seriously damaged and the deformation phenomena such as shrinking, shriveling and sinking occurred. Therefore, CLCEO has great potential for using as anti-mildew agents during peanut storage.

13.
Front Microbiol ; 13: 847167, 2022.
Article in English | MEDLINE | ID: mdl-35509308

ABSTRACT

Temperature changes have a great impact on fish feeding, intestinal microorganisms, metabolism, and immune function. Therefore, it is necessary to develop effective methods to enhance the survival rates and growth of fish under water temperature changes. Lactic acid bacteria (LAB) are promising immunostimulatory feed additive, as demonstrated by their beneficial effects in several fish species. This study investigated the short-term effects of dietary LAB on intestinal microbiota composition and immune responses of crucian carp (Carassius auratus) when water temperature decreased from 30 ± 1°C to 18 ± 1°C. Lactococcus (L.) lactis 1,209 and L. lactis 1,242 with potential probiotics isolated from the intestine of Qinghai naked carp (Gymnocypris przewalskii) were selected as feed additives for the crucian carp feeding experiment. A total of 225 commercially available healthy crucian carp (250 ± 10 g) of similar age were kept in 30°C water for a week and then immediately transferred to 18 ± 1°C water, assigned to three dietary treatments for a 16-day feeding trial randomly: (1) HC, diets without additives (the control group); (2) HT, diets with 106 CFU/ml L. lactis 1,209; and (3) HL, with 106 CFU/ml L. lactis 1,242. Each group was set up with 3 replicates and each with 25 fish. The results showed that the mortality rate of crucian carp in HC, HT, and HL group was 50, 27, and 33%, respectively. High-throughput sequencing results displayed that the composition of the intestinal microorganism varied dynamically in response to different treatments and water temperature decrease. Among them, compared with the HC group, a higher abundance of Firmicutes and Proteobacteria, and a lower of Actinobacteria appeared in HT and HL. The cytokines heat shock protein 70 (HSP-70) in crucian carp intestinal tract significantly decreased when water temperature decreased (p < 0.05).

14.
Front Microbiol ; 12: 671287, 2021.
Article in English | MEDLINE | ID: mdl-34177851

ABSTRACT

The corruption and/or poor quality of silages caused by low temperature and freeze-thaw conditions makes it imperative to identify effective starters and low temperature silage fermentation technology that can assist the animal feed industry and improve livestock productivity. The effect of L. plantarum QZ227 on the wheat silage quality was evaluated under conditions at constant low temperatures followed by repeated freezing and thawing at low temperatures. QZ227 became the predominant strain in 10 days and underwent a more intensive lactic acid bacteria fermentation than CK. QZ227 accumulated more lactic acid, but lower pH and ammonia nitrogen in the fermentation. During the repeated freezing and thawing process, the accumulated lactic acid in the silage fermented by QZ227 remained relatively stable. Relative to CK, QZ227 reduced the abundance of fungal pathogens in silage at a constant 5°C, including Aspergillus, Sporidiobolaceae, Hypocreaceae, Pleosporales, Cutaneotrichosporon, Alternaria, and Cystobasidiomycetes. Under varying low temperature conditions from days 40 to days 60, QZ227 reduced the pathogenic abundance of fungi such as Pichia, Aspergillus, Agaricales, and Plectosphaerella. QZ227 also reduced the pathogenic abundance of Mucoromycota after the silage had been exposed to oxygen. In conclusion, QZ227 can be used as a silage additive in the fermentation process at both constant and variable low temperatures to ensure fast and vigorous fermentation because it promotes the rapid accumulation of lactic acid, and reduces pH values and aerobic corruption compared to the CK.

15.
Front Vet Sci ; 8: 630294, 2021.
Article in English | MEDLINE | ID: mdl-33969032

ABSTRACT

Lactic acid bacteria (LAB) convert carbohydrates into organic acids [mainly lactic acid (LA)], which reportedly have bactericidal activities. Gallibacterium anatis is a Gram-negative bacteria which infects birds, and causes significant economic losses. In this study, we investigated the antibacterial activity of the LA producing, Leuconostoc mesenteroides QZ1178 from Qula (fermented food), against G. anatis, using the Oxford cup method. Our data showed that L. mesenteroides QZ1178 inhibited G. anatis isolates from different origins; however, L. mesenteroides QZ1178 antibacterial activity dropped dramatically at pH 5.5-pH 6. The LA concentration and pH of the liquid broth containing L. mesenteroides QZ1178 after 24 h culture was 29 mg/mL and 3.6, respectively. This concentration (29 mg/mL at pH 3.6) and the antibiotic, cefotaxime (minimum inhibitory concentration (MIC) 2.5 µg/mL) effectively inhibited G. anatis (GAC026) growth as observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Gallibacterium anatis treated with LA exhibited extensive cell surface collapse, increased cell damage, cell membrane disruption, and cytoplasmic leakage, indicative of cell lysis. We suggest L. mesenteroides QZ1178 exerts potential antibacterial effects against the poultry pathogen, G. anatis via LA.

16.
Front Microbiol ; 12: 614286, 2021.
Article in English | MEDLINE | ID: mdl-33584616

ABSTRACT

Leuconostoc mesenteroides strains were a type of epiphytic bacterium widely used in fermented foods and products in the biochemical and pharmaceutical industries but data on its presence in foods from Qinghai-Tibet Plateau in China was scarce. In this study, molecular analysis based on multilocus sequence typing (MLST) with eight housekeeping genes (pyrG, groeL, rpoB, recA, uvrC, murC, carB, and pheS) was carried out on 45 L. mesenteroides strains isolated from different plants and dairy products from Qinghai-Tibet Plateau in China. The objective of this study was to perform genetic diversity analysis and explore the relationship between strains and isolate samples or separate regions. A total of 25 sequence types (STs) were identified with a diversity of up to 55.6%, which were grouped into one clonal complexes (CCs), 3 doublets and 17 singletons by eBURST. The results of minimum spanning tree and clustering analysis indicated these L. mesenteroides strains from the Qinghai-Tibet Plateau were relatively weakly related to the isolated region. However, there was a close relationship between the genotypes of L. mesenteroides strains and the type of the isolated sample, which was consistent with the results of API 50CH. The MLST scheme presented in this study provides a shareable and comparable sequence database and enhances our knowledge of the population diversity of L. mesenteroides strains which will be further used for the selection of industrial strains.

17.
Probiotics Antimicrob Proteins ; 13(1): 90-101, 2021 02.
Article in English | MEDLINE | ID: mdl-32405962

ABSTRACT

In this study, we aimed to characterize lactic acid bacteria strains derived from infants' feces, to evaluate the probiotic potential and explore the wide-spectrum antimicrobial activity. Of 800 isolates, 20 inhibited the growth of enterotoxigenic Escherichia coli K88 and Salmonella enterica ATCC 13076. On the basis of 16S rRNA sequence analysis, the 20 isolates were assigned to Lactobacillus casei (7), Lactobacillus paracasei (2), Lactobacillus plantarum (4), Lactobacillus rhamnosus (2), Enterococcus avium (3), Enterococcus faecium (1), and Enterococcus lactis (1) species. In addition, 12 strains with high antimicrobial activity were investigated for the presence of probiotic properties such as physiological-biochemical characteristics, antimicrobial susceptibility, hemolytic activity, hydrophobicity, and aggregation activity. Wide-spectrum antimicrobial activity analysis revealed that approximately all tested strains inhibited the ten pathogens, and four strains (ZX221, ZX633, ZX3131, and ZX3875) had good probiotic properties and survived after being exposed to simulated gastrointestinal tract conditions. Moreover, we investigated the influence of pH on the wide-spectrum antimicrobial activity and found that four strains inhibited most pathogens at pH 4.5 and pH 5, whereas only ZX633 had an inhibitory effect on Bacillus subtilis ATCC 6633 and Micrococcus luteus ATCC 4698 at pH 5.5. Overall, Lact. casei ZX633 had wide-spectrum antimicrobial activity and could be considered a potential probiotic.


Subject(s)
Anti-Bacterial Agents , Bacillus subtilis/growth & development , Feces/microbiology , Lactobacillales , Micrococcus luteus/growth & development , Probiotics , Anti-Bacterial Agents/classification , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Humans , Infant , Lactobacillales/classification , Lactobacillales/isolation & purification , Probiotics/classification , Probiotics/isolation & purification , Probiotics/pharmacology
18.
Front Cell Infect Microbiol ; 10: 576185, 2020.
Article in English | MEDLINE | ID: mdl-33072628

ABSTRACT

We investigated the in vitro effects of Lactobacillus casei ZX633 on gut microorganism composition in infants with diarrhea. For this purpose, 103 feces samples from healthy infants (healthy group) and 300 diarrhea samples from infants (diarrhea group) were collected, and diarrhea feces were treated with L. casei ZX633, which was previously isolated from healthy infant feces (treatment group). We used microbial dilution plate methods, high performance liquid chromatography (HPLC) and high-throughput sequencing approaches to analyze viable main microorganism counts, short chain fatty acid (SCFA) concentrations, and intestinal microbiota composition in feces, respectively. Our data showed that L. casei ZX633 supplementation increased the numbers of Escherichia coli, yeasts, lactic acid bacteria (LAB) and aerobic-bacteria, raised propionic acid levels but reduced four other SCFAs, which are close to the healthy group. Alpha diversity results indicated that microbial diversity and richness decreased in treatment group. Bacterial community analyses revealed that microbial structures of the treatment group tended toward the healthy group; i.e., Escherichia-Shigella and Clostridioides abundance increased, and there was a reduction in the abundance of Streptococcus, Bacteroides, Enterococcus and Veillonella. In conclusion, L. casei ZX633 isolated from healthy infant feces, may be effective in improving infant diarrhea microbiota, potentially providing a new probiotic strain to reduce the incidence of diarrhea associated with bacterial disease in infants.


Subject(s)
Gastrointestinal Microbiome , Lacticaseibacillus casei , Probiotics , Diarrhea , Feces , Humans , Infant
19.
Int J Syst Evol Microbiol ; 70(4): 2713-2718, 2020 Apr.
Article in English | MEDLINE | ID: mdl-32176600

ABSTRACT

A new lanthanide (Ln3+)-dependent methanol-utilizing bacterial strain, La3113T, was isolated from rice field soil and its taxonomic position was investigated using polyphasic approaches. The strain was aerobic, Gram-stain-negative, strongly motile, catalase-positive and cytochrome oxidase-positive. It could neither catalyse the hydrolysis of urea nor reduce nitrate to nitrite. Growth was observed within a temperature range of 10-40 °C and a pH range of 6-8, with optimum growth at 28 °C and pH 7. Methylamine was utilized as the single source of energy, carbon and nitrogen, and it was oxidized by methylamine dehydrogenase. C16 : 1 ω7c, C16 : 1 ω6c and C16 : 0 were the dominant cellular fatty acids. Its draft genome (2.67 Mbp and 44.9 mol% G+C content) encodes genes including three Ln3+-dependent methanol dehydrogenase (XoxF-type MDH) genes, those for formaldehyde assimilation (ribulose monophosphate pathway), formate dehydrogenases and methylamine dehydrogenases, but not Ca2+-dependent MDH (MxaFI-MDH), which characterizes the species as a Ln3+-dependent methylotroph. The 16S rRNA gene sequence showed that strain La3113T belongs to the genus Methylotenera and is closely related to Methylotenera mobilis JLW8T (98.29 % identity). The digital DNA-DNA hybridization (dDDH) values (less than 30 %) and average nucleotide identity (ANI) values (less than 85 %) between genomes of strain La3113T and related type strains were lower than the thresholds for species delineation (70 % for dDDH and 95-96 % for ANI). On the basis of these polyphasic approaches, we propose a novel Methylotenera species, Methylotenera oryzisoli sp. nov. (type strain La3113T=NBRC 111954T=DSM 103219T).


Subject(s)
Lanthanoid Series Elements , Methylophilaceae/classification , Oryza , Phylogeny , Soil Microbiology , Bacterial Typing Techniques , Base Composition , DNA, Bacterial/genetics , Fatty Acids/chemistry , Genes, Bacterial , Japan , Methylophilaceae/isolation & purification , Nucleic Acid Hybridization , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA
20.
J Biosci Bioeng ; 126(6): 667-675, 2018 Dec.
Article in English | MEDLINE | ID: mdl-29914801

ABSTRACT

Oharaeibacter diazotrophicus strain SM30T, isolated from rice rhizosphere, is an aerobic, facultative lanthanide (Ln3+)-utilizing methylotroph and diazotroph that belongs to the Methylocystaceae family. In this research, the complete genome sequence of strain SM30T was determined, and its methylotrophy modules were characterized. The genome consists of one chromosome and two plasmids, comprising a total of 5,004,097 bp, and the GC content was 71.6 mol%. A total of 4497 CDSs, 67 tRNA, and 9 rRNA were encoded. Typical alpha-proteobacterial methylotrophy genes were found: pyrroloquinoline quinone (PQQ)-dependent methanol dehydrogenase (MDH) (mxaF and xoxF1-4), methylotrophy regulatory proteins (mxbDM and mxcQE), PQQ synthesis, H4F pathway, H4MPT pathway, formate oxidation, serine cycle, and ethylmalonyl-CoA pathway. SDS-PAGE and subsequent LC-MS analysis, and qPCR analysis revealed that MxaF and XoxF1 were the dominant MDH in the absence or presence of lanthanum (La3+), respectively. The growth of MDH gene-deletion mutants on alcohols and qPCR results indicated that mxaF and xoxF1 are also involved in ethanol and propanol oxidation, xoxF2 participates in methanol oxidation in the presence of La3+, while xoxF3 was associated with methanol and ethanol oxidation in the absence of La3+, implying that XoxF3 is a calcium (Ca2+)-binding XoxF. Four Ln3+ such as La3+, cerium (Ce3+), praseodymium (Pr3+), and neodymium (Nd3+) served as cofactors for XoxF1 by supporting ΔmxaF growth on methanol. Some heavier lanthanides inhibited growth of SM30 on methanol. This study contributes to the understanding of the function of various XoxF-type MDHs and their roles in methylotrophs.


Subject(s)
Genome, Bacterial/genetics , Methanol/metabolism , Methylocystaceae/genetics , Alcohol Oxidoreductases/genetics , Alphaproteobacteria/classification , Alphaproteobacteria/genetics , Alphaproteobacteria/metabolism , Base Composition , Chromosome Mapping , Ethanol/metabolism , Gene Expression Profiling , Gene Expression Regulation, Bacterial , Genomics/methods , Methylocystaceae/metabolism , Organisms, Genetically Modified , Oxidation-Reduction , PQQ Cofactor/genetics
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