Search Results (25)

Plant growth-promoting rhizobacteria (PGPR) offer a sustainable strategy for enhancing crop productivity and suppressing phytopathogens. In this study, seven bacterial isolates obtained from the rhizosphere of healthy tomato plants were evaluated for their antagonistic activity against the fungal pathogen Passalora fulva, the leaf miner Tuta absoluta, and their effects on tomato growth. In vitro dual-culture assays revealed that isolates IQR1, IQR2, IQR3, and IQR5 significantly inhibited P. fulva mycelial growth, with inhibition rates exceeding 35%. Volatile organic compounds (VOCs) produced by the bacterial isolates exhibited considerable antifungal activity, with IQR5, IQR1, and IQR2 achieving over 84% inhibition. Molecular identification based on 16S rDNA sequencing indicated that these isolates belong to distinct taxa: Leucobacter aridicolis (ON799334.1) (genus Leucobacter), Paenochrobactrum sp. (JF804769.1) (genus Paenochrobactrum), an uncultured bacterium (JQ337400.1) (genus Psychrobacter), and marine bacterium AK6_052 (KF816539.1) (genus Brevundimonas). Under greenhouse conditions, isolates IQR3, IQR5, and IQR1 reduced disease incidence of P. fulva to 20–26%. The same isolates also promoted plant growth, enhancing stem height and collar diameter. In addition, IQR5 significantly reduced T. absoluta larval density and foliar damage, with the number of larvae per leaflet decreasing to 1.42, compared to 3.20 in the control. These findings highlight the potentials of these rhizobacterial strains—particularly IQR5—as effective biocontrol agents and biofertilizers for integrated pest and disease management in tomato cultivation. Full article

Furfural is a relevant industrial product, but its presence in water and soil generates contamination and health risks. Moving bed biofilm reactors (MBBRs) are an increasingly used alternative to eliminate contaminants with the advantage of occupying small spaces, despite their high dependence on support and the microorganisms involved in the process. This work proposes furfural elimination through a laboratory-scale MBBR using Bacillus licheniformis GTQ1, Microbacterium sp. GISTAQ2, and Brevundimonas sp. GISTAQ1 isolated from an industrial effluent and agroforestry waste (rice husks, pine sawdust, and quebracho chips) as supports. The biofilm development was tested with both axenic and mixed cultures, confirming high coverage by Scanning Electron Microscope (SEM) images, especially in triple-mixed cultures. Biodegradation tests were carried out in the MBBR with 15 g rice husks or quebracho chips as supports and a 4000 mg L⁻¹ initial furfural concentration for 72 h. The mixed culture achieved almost a 100% furfural removal in three days with a rate of 3.97% per hour with rice husks and 2.61% per hour with quebracho chips. This laboratory-scale MBBR development is a promising first step ready for a scale-up for its implementation in industries to significantly reduce the environmental impact of the discharge of this type of effluent. Full article

A polyphasic taxonomic study was carried out on the rod-shaped, orange-pigmented strain C11^T, isolated from gold mine tailings. Sequencing of the 16S rRNA gene showed a relatedness to Brevundimonas, with a 98.4% and 98.2% similarity to Brevundimonas bacteroides and Brevundimonas variabilis, respectively. The average nucleotide identity and a digital DNA–DNA hybridization with the closest phylogenetic neighbor of strain C11^T indicate distinction at the species level, further confirmed by the differences in physiology. C_18:1 ω7c is the dominant cellular fatty acid. Its DNA G + C content is 68.3 mol %. Its predominant ubiquinone is Q-10; 1,2-Di-O-acyl-3-O-α-D-glucopyranuronosyl glycerol, phosphatidylglycerol, 1,2-di-O-acyl-3-O-α-D-glucopyranosyl glycerol, and 1,2-di-O-acyl-3-O-[D-glucopyranosyl-(1→4)-α-D-glucopyranuronosyl] glycerol are its major polar lipid constituents. This bacterium produces bacteriochlorophyll a and tolerates high concentrations of (μg/mL) the following: tellurium (>1500), selenium (1000 to >5000), and vanadium (>5000) oxyanions. The data support the inclusion of the strain C11^T into the genus Brevundimonas as a new species with the proposed name Brevundimonas aurifodinae sp. nov. (C11^T = NRRL B-65718^T; =DSM 118059^T). Full article

Argania spinosa is among the most important species of the Moroccan forest in terms of ecological, environmental, and socio-economic aspects. However, it faces a delicate balance between regeneration and degradation in its natural habitat. Hence, the efforts to preserve and regenerate argan forests are crucial for biodiversity, soil quality, and local livelihoods, yet they face challenges like overgrazing and climate change. Sustainable management practices, including reforestation and community engagement, are vital for mitigating degradation. Similarly, exploiting the argan tree’s rhizosphere can enhance soil quality by leveraging its rich microbial diversity. This approach not only improves crop growth but also maintains ecosystem balance, ultimately benefiting both agriculture and the environment. This enrichment can be achieved by different factors: mycorrhizae, plant extracts, algae extracts, and plant growth-promoting rhizobacteria (PGPR). The benefits provided by PGPR may include increased nutrient availability, phytohormone production, shoot, root development, protection against several plant pathogens, and disease reduction. In this study, the effect of rhizobacteria isolated from the Agran rhizosphere was evaluated on germination percentage and radicle length for Argania spinosa in vitro tests, growth, collar diameter, and branching number under greenhouse conditions. One hundred and twenty (120) bacteria were isolated from the argan rhizosphere and evaluated for their capacity for phosphate solubilization and indole acetic acid production. The results showed that 52 isolates could solubilize phosphorus, with the diameters of the solubilization halos varying from 0.56 ± 0.14 to 2.9 ± 0.08 cm. Among 52 isolates, 25 were found to be positive for indole acetic acid production. These 25 isolates were first tested on maize growth to select the most performant ones. The results showed that 14 isolates from 25 tested stimulated maize growth significantly, and 3 of them by 28% (CN005, CN006, and CN009) compared to the control. Eight isolates (CN005, CN006, CN004, CN007, CN008, CN009, CN010, and CN011) that showed plant growth of more than 19% were selected to evaluate their effect on argan germination rate and radicle length and were subjected to DNA extraction and conventional Sanger sequencing. The 8 selected isolates were identified as: Brevundimonas naejangsanensis sp2, Alcaligenes faecalis, Brevundimonas naejangsanensis sp3, Brevundimonas naejangsanensis sp4, Leucobacter aridicollis sp1, Leucobacter aridicollis sp2, Brevundimonas naejangsanensis sp1, and Staphylococcus saprophyticus. The results showed that Leucobacter aridicollis sp2 significantly increased the germination rate by 95.83%, and the radicle length with a value of 2.71 cm compared to the control (1.60 cm), followed by Brevundimonas naejangsanensis sp3 and Leucobacter aridicollis sp1 (2.42 cm and 2.11 cm, respectively). Under greenhouse conditions, the results showed that the height growth increased significantly for Leucobacter aridicollis sp1 (42.07%) and Leucobacter aridicollis sp2 (39.99%). The isolates Brevundimonas naejangsanensis sp3 and Leucobacter aridicollis sp1 increased the gain of collar diameter by 41.56 and 41.21%, respectively, followed by Leucobacter aridicollis sp2 and Staphyloccocus saprophyticus (38.68 and 22.79%). Leucobacter aridicollis sp1 increased the ramification number per plant to 12 compared to the control, which had 6 ramifications per plant. The use of these isolates represents a viable alternative in sustainable agriculture by improving the germination rate and root development of the argan tree, as well as its development, while increasing the availability of nutrients in the soil and consequently improving fertilization. Full article

Marine microorganisms have been demonstrated to be an important source for bioactive molecules. In this paper we report the synthesis of Ni nanoparticles (NiSNPs) used as reducing and capping agents for five bacterial strains isolated from an Antarctic marine consortium: Marinomonas sp. ef1, Rhodococcus sp. ef1, Pseudomonas sp. ef1, Brevundimonas sp. ef1, and Bacillus sp. ef1. The NiSNPs were characterized by Ultraviolet–visible (UV–vis) spectroscopy, Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopic analysis. The maximum absorbances in the UV–Vis spectra were in the range of 374 nm to 422 nm, corresponding to the Surface plasmon resonance (SPR) of Nickel. DLS revealed NiSNPs with sizes between 40 and 45 nm. All NiSNPs were polycrystalline with a face-centered cubic lattice, as revealed by XRD analyses. The NiSNPs zeta potential values were highly negative. TEM analysis showed that the NiSNPs were either spherical or rod shaped, well segregated, and with a size between 20 and 50 nm. The FTIR spectra revealed peaks of amino acid and protein binding to the NiSNPs. Finally, all the NiSNPs possess significant antimicrobial activity, which may play an important role in the management of infectious diseases affecting human health. Full article

Municipal wastewater treatment plants (WWTPs) are exposed to high concentrations of micropollutants that can impact conventional activated sludge treatment. The consequences of this include failure to meet discharge standards and the disintegration of flocs, leading to poor sludge settleability. This lab-scale study focuses on the influence of doxycycline, an antibiotic widely used against human and animal diseases, on protozoa, metazoa, and bacterial communities under sludge growing conditions. Doxycycline was added to the mixed liquor of a communal WWTP up to 0, 100, 200, and 400 mg of doxycycline L⁻¹ and incubated in batch conditions for 23 days. The regular addition of nutrient and carbon sources was preformed every 2 days to prevent sludge starvation. Sludge growth, conductivity, and settleability were measured and compared to sludge microbial community structure, determined by microscopic observations and high-throughput 16S rDNA sequencing. The high doxycycline concentration negatively impacted settleability and correlated with a decrease in bacterial diversity and floc disintegration. The addition of doxycycline promoted the enrichment of Proteobacteria Brevundimonas sp., Luteibacter anthropi, and the Bacteroidetes Chryseobacterium massoliae. These species are known to be resistant to a wide spectrum of antibiotics, including tetracyclines. A study of a larger scale may be conducted based on this study’ results. Full article

Phenanthrene (PHE) is one of the model compounds of polycyclic aromatic hydrocarbons (PAHs). In this study, a natural PHE-degrading microbial consortium, named HJ-SH, with very high degradation efficiency was isolated from soil exposed to long-term PHE contamination. The results of GC analysis showed that the consortium HJ-SH degraded 98% of 100 mg/L PHE in 3 days and 93% of 1000 mg/L PHE in 5 days, an efficiency higher than that of any other natural consortia, and even most of the engineered strains and consortia reported so far. Seven dominating strains were isolated from the microbial consortium HJ-SH, named SH-1 to SH-7, which were identified according to morphological observation and 16S rDNA sequencing as Pseudomonas sp., Stenotrophomonas sp., Delftia sp., Pseudomonas sp., Brevundimonas sp., Curtobacterium sp., and Microbacterium sp., respectively. Among all the seven single strains, SH-4 showed the strongest PHE degradation ability, and had the biggest degradation contribution. However, it is very interesting that the microbial consortium can hold its high degradation ability only with the co-existence of all these seven single strains. Moreover, HJ-SH exhibited a very high tolerance for PHE, up to 4.5 g/L, and it can degrade some other typical organic pollutants such as biphenyl, anthracene, and n-hexadecane with the degradation ratios of 93%, 92% and 70%, respectively, under 100 mg/L initial concentration in 5 days. Then, we constructed an artificial consortium HJ-7 consisting of the seven single strains, SH-1 to SH-7. After comparing the degradation ratios, cell growth, and relative degradation rates, it was concluded that the artificial consortium HJ-7 with easier reproducibility, better application stability, and larger room for modification can largely replace the natural consortium HJ-SH. In conclusion, this research provided novel tools and new insights for the bioremediation of PHE and other typical organic pollutants using microbial consortia. Full article

A native cyanide-degrading bacterial consortium was isolated from goldmine tailing sediments. Mine tailings are toxic effluents due to their metal–cyanide complexes. The bacterial consortium was able to degrade an initial sodium cyanide concentration ranging from 5 to 120 mg L⁻¹ in alkaline synthetic wastewater (pH > 9.2), for a maximum of 15 days. The free cyanide biodegradation efficiency was 98% for the highest initial free cyanide concentration tested and followed a first-order kinetic profile, with an estimated kinetic rate constant of 0.12 ± 0.011 d⁻¹. The cyanide-degrading consortium was streaked with serial dilutions on a specific medium (R2A). 16S rRNA gene sequencing and mass spectrometry proteomic fingerprinting of the isolates showed that the bacterial strains belonged to Microbacterium paraoxydans, Brevibacterium casei, Brevundimonas vesicularis, Bacillus cereus and Cellulosimicrobium sp. The first four genera had previously been identified as cyanide-degrading bacteria. Microbacterium and Brevibacterium had previously been found in alkaline conditions, showing resistance to heavy metals. As for Cellulosimicrobium, to our knowledge, this is the first study to implicate it directly or indirectly in cyanide biodegradation. In this research, these genera were identified as functional bacteria for cyanide degradation, and they might be suitable for mine tailing biotechnological tertiary treatment. Full article

Polystyrene (PS) and microplastic production pose persistent threats to the ecosystem. Even the pristine Antarctic, which is widely believed to be pollution-free, was also affected by the presence of microplastics. Therefore, it is important to comprehend the extent to which biological agents such as bacteria utilise PS microplastics as a carbon source. In this study, four soil bacteria from Greenwich Island, Antarctica, were isolated. A preliminary screening of the isolates for PS microplastics utilisation in the Bushnell Haas broth was conducted with the shake-flask method. The isolate AYDL1 identified as Brevundimonas sp. was found to be the most efficient in utilising PS microplastics. An assay on PS microplastics utilisation showed that the strain AYDL1 tolerated PS microplastics well under prolonged exposure with a weight loss percentage of 19.3% after the first interval (10 days of incubation). Infrared spectroscopy showed that the bacteria altered the chemical structure of PS while a deformation of the surface morphology of PS microplastics was observed via scanning electron microscopy after being incubated for 40 days. The obtained results may essentially indicate the utilisation of liable polymer additives or “leachates” and thus, validate the mechanistic approach for a typical initiation process of PS microplastics biodeterioration by the bacteria (AYDL1)—the biotic process. Full article

Research on Plant Growth-Promoting Bacteria (PGPB) has focused much more on rhizospheric bacteria. However, PGPB associated with toxic cyanobacterial bloom (TCB) could enter the rhizosphere through irrigation water, helping plants such as Pisum sativum L. (pea) overcome oxidative stress induced by microcystin (MC) and improve plant growth and nutritional value. This study aimed to isolate bacteria associated with toxic cyanobacteria, test PGPB properties, and inoculate them as a consortium to pea seedlings irrigated with MC to investigate their role in plant protection as well as in improving growth and nutritional value. Two bacterioplankton isolates and one rhizosphere isolate were isolated and purified on a mineral salt medium supplemented with 1000 μg/L MC and identified via their 16S rRNA gene. The mixed strains were inoculated to pea seedlings in pots irrigated with 0, 50, and 100 μg/L MC. We measured the morphological and physiological parameters of pea plants at maturity and evaluated the efficiency of the plant’s enzymatic and non-enzymatic antioxidant responses to assess the role and contribution of PGPB. Both bacterioplankton isolates were identified as Starkeya sp., and the rhizobacterium was identified as Brevundimonas aurantiaca. MC addition significantly (p < 0.05) reduced all the growth parameters of the pea, i.e., total chlorophyll content, leaf quantum yield, stomatal conductance, carotenoids, and polyphenol contents, in an MC concentration-dependent manner, while bacterial presence positively affected all the measured parameters. In the MC treatment, the levels of the pea’s antioxidant traits, including SOD, CAT, POD, PPO, GST, and ascorbic acid, were increased in the sterile pots. In contrast, these levels were reduced with double and triple PGPB addition. Additionally, nutritional values such as sugars, proteins, and minerals (Ca and K) in pea fruits were reduced under MC exposure but increased with PGPB addition. Overall, in the presence of MC, PGPB seem to positively interact with pea plants and thus may constitute a natural alternative for soil fertilization when irrigated with cyanotoxin-contaminated water, increasing the yield and nutritional value of crops. Full article

Lake Vostok is the deepest lake of Antarctica but has poor accessibility for study due to a thick glacial cover, however, water samples of this lake have become available for study just recently. Previously, only the microbiome of the ice cover samples was characterized. Here we report results of bacteriological seeding with subsequent identification of the heterotrophic microorganisms (bacteria and micellar fungi) present by 16S rDNA sequencing as well as results of a direct molecular study of the water microbiome. Surprisingly, the data obtained gave evidence of a predominant occurrence of common chemoorganotrophs that were rather psychrotolerant than psychrophilic. We isolated and described strains belonging to eight heterotrophic microbial species able to grow in a rich medium: six bacterial strains belonging to the species Microbacterium testaceum and Microbacterium trichothecenolyticum, Brevundimonas diminuta, Sphingomonas oligophenolica, Sphingomonas sp. and Sphingobium limneticum; and two fungal strains belonging to Dendryphion sp. and Cladosporium fusiforme. Direct study of 16S rDNA purified water samples confirmed the predominance of the Brevundimonas, Microbacterium, Bradyrhizobium, and Bacillus (Bacillus cereus) genera. Full article

In classical microbiology, developing a high-efficiency bacterial consortium is a great challenge for faster biodegradation of petroleum contaminants. In this study, a systematic experimental and mathematical procedure was adopted to establish a bacterial consortium for the effective biodegradation of heavy oil constituents. A total of 27 bacterial consortia were established as per orthogonal experiments, using 8 petroleum-degrading bacterial strains. These bacteria were closer phylogenetic relatives of Brevundimonas sp. Tibet-IX23 (Y1), Bacillus firmus YHSA15, B. cereus MTCC 9817, B. aquimaris AT8 (Y2, Y6 and Y7), Pseudomonas alcaligenes NBRC (Y3), Microbacterium oxydans CV8.4 (Y4), Rhodococcus erythropolis SBUG 2052 (Y5), and Planococcus sp. Tibet-IX21 (Y8), and were used in different combinations. Partial correlation analysis and a general linear model hereafter were applied to investigate interspecific relationships among different strains and consortia. The Y1 bacterial species showed a remarkable synergy, whereas Y3, Y4, and Y6 displayed a strong antagonism in all consortia. Inoculation ratios of different strains significantly influenced biodegradation. An optimal consortium was constructed with Y1, Y2, Y5, Y7, and Y8, which revealed maximum degradation of 11.238 mg/mL OD₆₀₀ for oil contaminants. This study provides a line of evidence that a functional consortium can be established by mathematical models for improved bioremediation of petroleum-contaminated environment. Full article

The continued discharge of pharmaceuticals and personal care products (PPCPs) into the environment due to their widespread use and the lack of effective systems for their removal from water is a global problem. In this study, the dissipation of ibuprofen, diclofenac and triclosan added simultaneously in biopurification systems (BPSs) with different compositions and their effect on the microbial community structure was analysed. Three BPSs, constituted by mixtures of soil (S), peat (P), or raw wet olive mill cake (A) or its vermicompost (V) and straw (S) were prepared (SPS, SAS and SVS). Sorption and degradation experiments were carried out. After 84 days of incubation, more than 85% of each PPCP applied had dissipated. Methyl-triclosan was determined to be highest in the SVS biomixture. Biomixtures with lower C/N ratio and higher alpha diversity were the most effective in the removal of PPCPs. Initially, the BPS biomixtures showed a different microbial structure dominated by Proteobacteria, Actinobacteria and Bacteroidetes but after addition of PPCPs, a similar pattern was observed in the relative abundance of the phylum Chloroflexi, the class Sphingobacteriia and the genus Brevundimonas. These biopurification systems can be useful to prevent point source contamination due to the disposal of PPCP-contaminated waters. Full article

Brevundimonas sp. is a bacteria able to grow in metal(loid) contaminated soil from Puchuncaví Valley, central Chile. This study has isolated a bacterial strain capable of growth under high doses of arsenic (As) (6000 mg L⁻¹), and a draft genome sequence was generated. Additionally, real-time PCR was performed to examine the effect of As on some genes related to As resistance. Results demonstrated a total of 3275 predicted annotated genes with several genes related to the ars operon, metal(loid) resistance-related genes, metal efflux pumps, and detoxifying enzymes. Real-time PCR showed that the arsB involved in the efflux of As was down-regulated, whereas arsR, arsH, and ACR3 did not show differences with the addition of As. Our study provides novel evidence of diverse As regulating systems in tolerant bacteria that will lead to a better understanding of how microorganisms overcome toxic elements and colonize As contaminated soils and to the possible use of their specific properties in bioremediation. Full article