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A Gram-positive, aerobic, rod-shaped non-motile, non-sporulating bacterium, designated CSA2T, was isolated from chromium-containing soils collected from a chemical plant. The 16S rRNA gene sequence of strain CSA2T showed the highest homology with Leucobacter chromiireducens subsp. solipictus (97.85%), Leucobacter chromiireducens subsp. chromiireducens (97.85%). The digital DNA-DNA hybridization (dDDH), average nucleotide identity (ANI) and the amino acid identity (AAI) values among strains CSA2T and the selected Leucobacter species were 20.6–23.4% (dDDH), 72.67–78.03% (ANI) and 66.39–76.16% (AAI), falling below the recommended thresholds for species delimitation. The principal fatty acids were anteiso-C15:0, iso-C16:0 and anteiso-C17:0. The polar lipids were phosphatidylglycerol, diphosphatidylglycerol and an unknown glycolipid. The major menaquinones detected were MK-10 and MK-11. The cell-wall amino acids included 2,4-diaminobutyric acid, threonine, glutamic acid, alanine and glycine. Based on molecular feature, phenotypic and chemotaxonomic, strain CSA2T was considered to be a novel species of the genus Leucobacter., and the name Leucobacter edaphi sp. nov. is proposed. The type strain is CSA2T (= JCM 34360T = CGMCC 1.18747T).

Abstract Gut microbial communities of mosquitoes can influence vector susceptibility to pathogens, yet the factors that govern their composition remain poorly understood. We investigated the impact of host blood-meal source on gut microbiota of Aedes aegypti L. Adult mosquitoes were fed on human, rabbit or chicken blood and their gut microbiota compared to those of sugar-fed and newly emerged adults. Microbial diversity was significantly reduced in blood-fed and sugar-fed mosquitoes but was restored to the levels of newly emerged adults at 7-days post-blood meal. Microbial composition was strongly influenced by host blood-meal source. Leucobacter spp., Chryseobacterium spp., Elizabethkingia spp. and Serratia spp. were characteristic of newly emerged adults and adults fed on chicken, rabbit and human blood, respectively. Sugar-fed mosquitoes had higher abundance of Pseudomonas spp. and unclassified Acetobacteraceae. Shifts in gut microbial communities in response to host blood-meal source may fundamentally impact pathogen transmission given the well-documented link between specific bacterial taxa and vector susceptibility to a variety of mosquito-borne pathogens and may be a key determinant of individual and population variation in vector competence. Gut bacterial communities of Aedes aegypti shift in response to host blood-meal source.

Pharmaceuticals are of concern to our planet and health as they can accumulate in the environment. The impact of these biologically active compounds on ecosystems is hard to predict, and information on their biodegradation is necessary to establish sound risk assessment. Microbial communities are promising candidates for the biodegradation of pharmaceuticals such as ibuprofen, but little is known yet about their degradation capacity of multiple micropollutants at higher concentrations (100 mg/L). In this work, microbial communities were cultivated in lab-scale membrane bioreactors (MBRs) exposed to increasing concentrations of a mixture of six micropollutants (ibuprofen, diclofenac, enalapril, caffeine, atenolol, paracetamol). Key players of biodegradation were identified using a combinatorial approach of 16S rRNA sequencing and analytics. Microbial community structure changed with increasing pharmaceutical intake (from 1 to 100 mg/L) and reached a steady-state during incubation for 7 weeks on 100 mg/L. HPLC analysis revealed a fluctuating but significant degradation (30–100%) of five pollutants (caffeine, paracetamol, ibuprofen, atenolol, enalapril) by an established and stable microbial community mainly composed of Achromobacter, Cupriavidus, Pseudomonas and Leucobacter. By using the microbial community from MBR1 as inoculum for further batch culture experiments on single micropollutants (400 mg/L substrate, respectively), different active microbial consortia were obtained for each single micropollutant. Microbial genera potentially responsible for degradation of the respective micropollutant were identified, i.e. Pseudomonas sp. and Sphingobacterium sp. for ibuprofen, caffeine and paracetamol, Sphingomonas sp. for atenolol and Klebsiella sp. for enalapril. Our study demonstrates the feasibility of cultivating stable microbial communities capable of degrading simultaneously a mixture of highly concentrated pharmaceuticals in lab-scale MBRs and the identification of microbial genera potentially responsible for the degradation of specific pollutants.Key points• Multiple pharmaceuticals were removed by stable microbial communities.• Microbial key players of five main pharmaceuticals were identified.

Antibiotic ciprofloxacin is ubiquitous in the environment. However, little is known about ciprofloxacin dissipation by microbial community. The present study investigated the biodegradation potential of ciprofloxacin by mixed culture and the influential factors and depicted the structure of ciprofloxacin-degrading microbial community. Both the original microbiota from drinking water biofilter and the microbiota previously acclimated to high levels of ciprofloxacin could utilize ciprofloxacin as sole carbon and nitrogen sources, while the acclimated microbiota had a much stronger removal capacity. Temperature rise and the presence of carbon or nitrogen sources favored ciprofloxacin biodegradation. Many novel biotransformation products were identified, and four different metabolic pathways for ciprofloxacin were proposed. Bacterial community structure illustrated a profound shift with ciprofloxacin biodegradation. The ciprofloxacin-degrading bacterial community was mainly composed of classes Gammaproteobacteria , Bacteroidia , and Betaproteobacteria . Microorganisms from genera Pseudoxanthomonas , Stenotrophomonas , Phenylobacterium , and Leucobacter might have links with the dissipation of ciprofloxacin. This work can provide some new insights towards ciprofloxacin biodegradation.

In the last decade, biological degradation and mineralization of antibiotics have been increasingly reported feats of environmental bacteria. The most extensively described example is that of sulfonamides that can be degraded by several members of Actinobacteria and Proteobacteria. Previously, we reported sulfamethoxazole (SMX) degradation and partial mineralization by Achromobacter denitrificans strain PR1, isolated from activated sludge. However, further studies revealed an apparent instability of this metabolic trait in this strain. Here, we investigated this instability and describe the finding of a low-abundance and slow-growing actinobacterium, thriving only in co-culture with strain PR1. This organism, named GP, shared highest 16S rRNA gene sequence similarity (94.6–96.9%) with the type strains of validly described species of the genus Leucobacter. This microbial consortium was found to harbor a homolog to the sulfonamide monooxygenase gene (sadA) also found in other sulfonamide-degrading bacteria. This gene is overexpressed in the presence of the antibiotic, and evidence suggests that it codes for a group D flavin monooxygenase responsible for the ipso-hydroxylation of SMX. Additional side reactions were also detected comprising an NIH shift and a Baeyer–Villiger rearrangement, which indicate an inefficient biological transformation of these antibiotics in the environment. This work contributes to further our knowledge in the degradation of this ubiquitous micropollutant by environmental bacteria.

A novel yellow pigmented, Gram-positive, aerobic and heavy metal biosorptive bacterium designated SYP-B2667T was isolated from rhizosphere soil of Epilobium hirsutum L. in Tongren, Guizhou province, China. Based on 16S rRNA gene sequence analyses, it was shown that strain SYP-B2667T represents a novel species in the genus Leucobacter, with Leucobacter chromiireducens subsp. solipictus JCM 15573T as a close phylogenetic neighbour (sequence similarity of 98.2%). Chemotaxonomic characteristics also supported the affiliation to the genus Leucobacter. Strain SYP-B2667T was determined to have a DNA G+C content of 66.6 mol%; 2,4-diaminobutyric acid in the cell wall peptidoglycan amino acids; MK-11 as predominant menaquinone; an abundance of anteiso-C15:0 and anteiso-C17:0 fatty acids; and polar lipids including diphosphatidylglycerol, phosphatidylglycerol, glycolipids and unidentified phospholipids. The DNA–DNA hybridization value between strain SYP-B2667T and L. chromiireducens subsp. solipictus JCM 15573T was 19.7 ± 2.8%. Based on these phylogenetic and phenotypic results, it can be concluded that strain SYP-B2667T represents a novel species, for which the name Leucobacter epilobiisoli sp. nov. is proposed. The type strain is SYP-B2667T (=DSM 105145T=CPCC 204976T). This strain can tolerate and adsorb five heavy metals and so may have potential to facilitate heavy metal removal and bioremediation.

Bacteria are part of the insect gut system and influence many physiological traits of their host. Gut bacteria may even reduce or block the transmission of arboviruses in several species of arthropod vectors. Culicoides biting midges are important arboviral vectors of several livestock and wildlife diseases, yet limited information is available on their gut bacterial communities. Addressing this gap will help inform how these communities can be manipulated and ultimately used as novel tools to control pathogens. To assess how bacterial communities change during the life stages of lab-reared C. nubeculosus and C. sonorensis, endosymbiotic bacteria were identified using Illumina sequencing of 16S rRNA and taxonomically characterised. Analyses were conducted to determine how gut bacterial communities in adults are influenced by species identity and geographic distance among biting midge populations. Communities of the two lab-reared Culicoides species significantly changed after pupation and with maturation into 6-day-old adults. Pseudomonas, Burkholderiaceae and Leucobacter bacteria were part of a core community that was trans-stadially transmitted and found throughout their life cycle. Among field-collected biting midges, the bacterial communities were unique for almost each species. Cardinium, Rickettsia and Wolbachia were some of the most abundant bacteria in midges collected from wetlands. Only Pseudomonas was present in high relative abundance in all field-collected species. In this study, species identity, as well as geographic distance, influenced the gut bacterial communities and may partly explain known inter- and intra-species variability in vector competence. Additionally, stably associated bacterial species could be candidates for paratransgenic strategies to control vector-borne pathogens.

The current investigation addressed the green synthesis of silver nanoparticles (AgNPs) using newly isolated silver-resistant rare actinomycetes, Glutamicibacter nicotianae SNPRA1 and Leucobacter aridicollis SNPRA2, and investigated their impact on the mycotoxigenic fungi Aspergillus flavus ATCC 11498 and Aspergillus ochraceus ATCC 60532. The formation of AgNPs was evidenced by the reaction’s color change to brownish and the appearance of the characteristic surface plasmon resonance. The transmission electron microscopy of biogenic AgNPs produced by G. nicotianae SNPRA1 and L. aridicollis SNPRA2 (designated Gn-AgNPs and La-AgNPs, respectively) revealed the generation of monodispersed spherical nanoparticles with average sizes of 8.48 ± 1.72 nm and 9.67 ± 2.64 nm, respectively. Furthermore, the XRD patterns reflected their crystallinity and the FTIR spectra demonstrated the presence of proteins as capping agents. Both bioinspired AgNPs exhibited a remarkable inhibitory effect on the conidial germination of the investigated mycotoxigenic fungi. The bioinspired AgNPs caused an increase in DNA and protein leakage, suggesting the disruption of membrane permeability and integrity. Interestingly, the biogenic AgNPs completely inhibited the production of total aflatoxins and ochratoxin A at concentrations less than 8 μg/mL. At the same time, cytotoxicity investigations revealed the low toxicity of the biogenic AgNPs against the human skin fibroblast (HSF) cell line. Both biogenic AgNPs exhibited feasible biocompatibility with HSF cells at concentrations up to 10 μg/mL and their IC50 values were 31.78 and 25.83 μg/mL for Gn-AgNPs and La-AgNPs, respectively. The present work sheds light on the antifungal prospect of the biogenic AgNPs produced by rare actinomycetes against mycotoxigenic fungi as promising candidates to combat mycotoxin formation in food chains at nontoxic doses.

Water samples taken from the Çubuk Stream (Ankara, Turkey) were inoculated into nutrient broth media containing Setazol Navy Blue SBG (SNB), an organic pollutant, and heavy metal Cr(VI), an inorganic pollutant, to obtain a pollutant-resistant mixed microbial culture. Experiments were conducted with this culture to remove SNB and heavy metal. The optimum conditions, where the mixed bacterial culture removed the pollutants most effectively, were determined, showing that the highest capacity for removal took place at pH 8 with removal percentages 96.3% for Cr(VI) and 78.5% for SNB. In media with 50.4 mg/L SNB and 9.7 mg/L Cr(VI), the SNB removal was 87.3%, and the Cr(VI) removal was 96.6% at the end of the 7-day incubation period. The highest removal was observed with a biomass concentration of 8% (v/v) of mixed culture [50 mg/L SNB dye+25 mg/L Cr(VI)]. The removal was 100% for both Cr(VI) and the SNB dye. The bacteria with the highest removal were isolated and identified using 16S rDNA gene sequence analysis as Microbacterium oxydans and Leucobacter aridicollis. The role of various functional groups and the structures of the microorganisms that might be involved in the removal mechanisms were discussed using their FTIR spectra. This report is the first study that investigates a mixed bacterial culture and pure cultures (M. oxydans and L. aridicollis) isolated from that mixed culture, removing both SNB and Cr(VI) simultaneously.

Poorly-treated wastewater harbors harmful microorganisms, posing risks to both the environment and public health. To mitigate this, it is essential to implement robust disinfection techniques in wastewater treatment plants. The use of performic acid (PFA) oxidation has emerged as a promising alternative, due to its powerful disinfection properties and minimal environmental footprint. While PFA has been used to inactivate certain microbial indicators, its potential to tackle the entire microbial community in effluents, particularly resistant bacterial strains, remains largely unexplored. The present study evaluates the efficacy of PFA disinfection on the microbial communities of a WWTP effluent, through microbial resistance mechanisms due to their membrane structure. The effluent microbiome was quantified and identified. The results showed that the number of damaged cells increases with CT, reaching a maximum for CT = 240 mg/L•min and plateauing around 60 mg/L•min, highlighting the optimal conditions for PFA-disinfection against microbial viability. A low PFA level with a 10-min contact time significantly affected the microbial composition. It is worth noting the sensitivity of several bacterial genera such as Flavobacterium , Pedobacter , Massilia , Exiguobacterium , and Sphingorhabdus to PFA, while others, Acinetobacter , Leucobacter , Thiothrix , Paracoccus , and Cloacibacterium , showed resistance. The results detail the resistance and sensitivity of bacterial groups to PFA, correlated with their Gram-positive or Gram-negative membrane structure. These results underline PFA effectiveness in reducing microbial levels and remodeling bacterial composition, even with minimal concentrations and short contact times, demonstrating its suitability for widespread application in WWTPs.