RESUMO
Soil alkalinity is a critical environmental factor for plant growth and distribution in ecosystems. An alkaline condition (pH > 7) is imposed by the rising concentration of hydroxides and cations, and prevails in semiarid and arid environments, which represent more than 25% of the total arable land of the world. Despite the great pressure exerted by alkalinity for root viability and plant survival, scarce information is available to understand how root microbes contribute to alkaline pH adaptation. Here, we assessed the effects of alkalinity on shoot and root biomass production, chlorophyll content, root growth and branching, lateral root primordia formation, and the expression of CYCB1, TOR kinase, and auxin and cytokinin-inducible trangenes in shoots and roots of Arabidopsis seedlings grown in Petri plates with agar-nutrient medium at pH values of 7.0, 7.5, 8.0, 8.5, and 9.0. The results showed an inverse correlation between the rise of pH and most growth, hormonal and genetic traits analyzed. Noteworthy, root inoculation with Achromobacter sp. 5B1, a beneficial rhizospheric bacterium, with plant growth promoting and salt tolerance features, increased biomass production, restored root growth and branching and enhanced auxin responses in WT seedlings and auxin-related mutants aux1-7 and eir1, indicating that stress adaptation operates independently of canonical auxin transporter proteins. Sequencing of the Achromobacter sp. 5B1 genome unveiled 5244 protein-coding genes, including genes possibly involved in auxin biosynthesis, quorum-sensing regulation and stress adaptation, which may account for its plant growth promotion attributes. These data highlight the critical role of rhizobacteria to increase plant resilience under high soil pH conditions potentially through genes for adaptation to an extreme environment and bacteria-plant communication.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Plântula , Proteínas de Arabidopsis/genética , Ecossistema , Raízes de Plantas , Ácidos Indolacéticos/metabolismo , Solo , Regulação da Expressão Gênica de PlantasRESUMO
This study aimed to investigate the antimicrobial resistance profile to quinolones, the presence of quinolone-resistant determinants and the plasmid replicon typing in environmental Achromobacter sp. isolated from Brazil. Soil and water samples were used for bacterial isolation. The antimicrobial susceptibility testing was performed by minimum inhibitory concentration method. The detection of mutations in the quinolone resistance-determining regions (QRDR) genes, the presence of plasmid-mediated quinolone resistance (PMQR) genes, and plasmid replicons were performed by PCR. A total of 16 isolates was obtained from different cultures, cities, and states of Brazil. All isolates were non-susceptible to ciprofloxacin, norfloxacin, and levofloxacin. Some mutations in QRDR genes were found, including Gln-83-Leu and Asp-87-Asn in the gyrA and Gln-80-Ile and Asp-84-Ala in the parC. Different PMQR genes were detected, such as qnrA, qnrB, qnrS, oqxA, and oqxB. Three different plasmid families were detected, being most presented the ColE-like, followed by IncFIB and IncA/C. The presence of different PMQR genes and plasmids in the isolates of the present study shows that environmental bacteria can act as reservoir of important genes of resistance to fluoroquinolones, which is of great concern, due to the potential of horizontal dissemination of these genes. Besides that, there are no studies reporting these results in Achromobacter sp. isolates.
Assuntos
Achromobacter/genética , Antibacterianos/farmacologia , Técnicas de Tipagem Bacteriana/métodos , Farmacorresistência Bacteriana/genética , Plasmídeos/química , Replicon , Achromobacter/efeitos dos fármacos , Achromobacter/crescimento & desenvolvimento , Achromobacter/metabolismo , Sequência de Aminoácidos , Brasil , Ciprofloxacina/farmacologia , DNA Girase/genética , DNA Girase/metabolismo , DNA Topoisomerase IV/genética , DNA Topoisomerase IV/metabolismo , Expressão Gênica , Humanos , Levofloxacino/farmacologia , Testes de Sensibilidade Microbiana , Mutação , Norfloxacino/farmacologia , Plasmídeos/metabolismo , Microbiologia do Solo , Microbiologia da ÁguaRESUMO
OBJECTIVES: Bacteria belonging to the genera Ochrobactrum and Achromobacter are bacteria considered opportunistic, causing infections mainly in immunocompromised patients. ß-lactamases are the main cause of resistance to ß-lactam antibiotics. This study aimed to investigate the antimicrobial resistance profile and the presence of ß-lactamases encoding genes in Ochrobactrum sp. and Achromobacter sp. isolated from Brazilian soils. METHODS: Soil samples from the five regions of Brazil were collected for the isolation of bacteria, which were identified molecularly and then, the minimum inhibitory concentration and detection of ß-lactamases encoding genes were performed. RESULTS: High-level of resistance to ß-lactam antibiotics and different ß-lactamases encoding genes were found (blaCTX-M-Gp1, blaSHV, blaOXA-1-like and blaKPC), including the first report of the presence of blaKPC in bacteria belonging to the genera Ochrobactrum and Achromobacter. CONCLUSION: The results showed that the bacteria from this study, belonging to genera Ochrobactrum and Achromobacter isolated from soil, harbor different ß-lactamases encoding genes and can act as a reservoir of these genes.
Assuntos
Achromobacter/isolamento & purificação , Ochrobactrum/isolamento & purificação , beta-Lactamases/genética , beta-Lactamas/farmacologia , Achromobacter/genética , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Brasil , Testes de Sensibilidade Microbiana , Ochrobactrum/genética , Microbiologia do Solo , Resistência beta-LactâmicaRESUMO
Microbial degradation constitutes the key soil dissipation process for iprodione. We recently isolated a consortium, composed of an Arthrobacter sp. strain C1 and an Achromobacter sp. strain C2, that was able to convert iprodione to 3,5-dichloroaniline (3,5-DCA). However, the formation of metabolic intermediates and the role of the strains on iprodione metabolism remain unknown. We examined the degradation of iprodione and its suspected metabolic intermediates, 3,5-dichlorophenyl-carboxamide (metabolite I) and 3,5-dichlorophenylurea-acetate (metabolite II), by strains C1 and C2 and their combination under selective (MSM) and nutrient-rich conditions (LB). Bacterial growth during degradation of the tested compounds was determined by qPCR. Strain C1 rapidly degraded iprodione (DT50 = 2.3 h) and metabolite II (DT50 = 2.9 h) in MSM suggesting utilization of isopropylamine, transiently formed by hydrolysis of iprodione, and glycine liberated during hydrolysis of metabolite II, as C and N sources. In contrast, strain C1 degraded metabolite I only in LB and growth kinetics suggested the involvement of a detoxification process. Strain C2 was able to transform iprodione and its metabolites only in LB. Strain C1 degraded vinclozolin, a structural analog of iprodione, and partially propanil, but not procymidone and phenylureas indicating a structure-dependent specificity related to the substituents of the carboxamide moiety.
Assuntos
Aminoimidazol Carboxamida/análogos & derivados , Bactérias/metabolismo , Fungicidas Industriais/metabolismo , Hidantoínas/metabolismo , Microbiologia do Solo , Aminoimidazol Carboxamida/metabolismo , Compostos de Anilina/metabolismo , Biodegradação Ambiental , Redes e Vias Metabólicas , Oxazóis/metabolismo , Propanil/metabolismoRESUMO
Microorganisms play an important role in the biodegradation of petroleum contaminants, which have attracted great concern due to their persistent toxicity and difficult biodegradation. In this paper, a novel hydrocarbon-degrading bacterium HZ01 was isolated from the crude oil-contaminated seawater at the Daya Bay, South China Sea, and identified as Achromobacter sp. Under the conditions of pH 7.0, NaCl 3% (w/v), temperature 28 °C and rotary speed 150 rpm, its degradability of the total n-alkanes reached up to 96.6% after 10 days of incubation for the evaporated diesel oil. Furthermore, Achromobacter sp. HZ01 could effectively utilize polycyclic aromatic hydrocarbons (PAHs) as its sole carbon source, and could remove anthracene, phenanthrene and pyrence about 29.8%, 50.6% and 38.4% respectively after 30 days of incubation. Therefore, Achromobacter sp. HZ01 may employed as an excellent degrader to develop one cost-effective and eco-friendly method for the bioremediation of marine environments polluted by crude oil.