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Shortened chromatograms of LC-MS data gathered in positive mode of the five samples with Fe-chelating and As-binding activities derived from HPLC with gradient elution with a referring to sample 1, b to sample 2, etc. Samples 1 to 4 represent different fractions from HPLC with gradient elution derived from Fe-free medium without arsenite. Sample 5 represents an HPLC fraction derived from the culture with 937 μM arsenite. The original chromatograms cover 30 min and are available as Supplementary Material (Fig. S4). Labels are identified and putative heterobactins (see Figs. 4 and 5 and Table S4). Shown are significant figures, meaning that the average measurement inaccuracy can statistically be found in the last digit given
Source publication
Rhodococcus erythropolis S43 is an arsenic-tolerant actinobacterium isolated from an arsenic contaminated soil. It has been shown to produce siderophores when exposed to iron-depleting conditions. In this work, strain S43 was shown to have the putative heterobactin production cluster htbABCDEFGHIJ(K). To induce siderophore production, the strain wa...
Citations
... Through their metal-chelating properties, heterobactins play a pivotal role in the collaborative biocontrol efficacy of R. erythropolis against phytopathogens. In addition, these molecules have demonstrated an affinity for binding to arsenic [37,38]. The aforementioned details underscore the prospective utility of MGMM8 in diverse domains such as medicine, plant protection, and bioremediation. ...
Anthropogenic pollution, including residues from the green revolution initially aimed at addressing food security and healthcare, has paradoxically exacerbated environmental challenges. The transition towards comprehensive green biotechnology and bioremediation, achieved with lower financial investment, hinges on microbial biotechnology, with the Rhodococcus genus emerging as a promising contender. The significance of fully annotating genome sequences lies in comprehending strain constituents, devising experimental protocols, and strategically deploying these strains to address pertinent issues using pivotal genes. This study revolves around Rhodococcus erythropolis MGMM8, an associate of winter wheat plants in the rhizosphere. Through the annotation of its chromosomal genome and subsequent comparison with other strains, its potential applications were explored. Using the antiSMASH server, 19 gene clusters were predicted, encompassing genes responsible for antibiotics and siderophores. Antibiotic resistance evaluation via the Comprehensive Antibiotic Resistance Database (CARD) identified five genes (vanW, vanY, RbpA, iri, and folC) that were parallel to strain CCM2595. Leveraging the NCBI Prokaryotic Genome Annotation Pipeline (PGAP) for biodegradation, heavy metal resistance, and remediation genes, the presence of chlorimuron-ethyl, formaldehyde, benzene-desulfurization degradation genes, and heavy metal-related genes (ACR3, arsC, corA, DsbA, modA, and recG) in MGMM8 was confirmed. Furthermore, quorum-quenching signal genes, critical for curbing biofilm formation and virulence elicited by quorum-sensing in pathogens, were also discerned within MGMM8’s genome. In light of these predictions, the novel isolate MGMM8 warrants phenotypic assessment to gauge its potential in biocontrol and bioremediation. This evaluation extends to isolating active compounds for potential antimicrobial activities against pathogenic microorganisms. The comprehensive genome annotation process has facilitated the genetic characterization of MGMM8 and has solidified its potential as a biotechnological strain to address global anthropogenic predicaments.
... Finally, ARC_M6 and ARC_M8 encoded CtpD protein, which, like CtpC, is involved in resistance to divalent metal ions (Raimunda et al., 2012). The metal-related phenotype testing results are in line with already published data regarding high levels of arsenic resistance observed for Rhodococcus members (Firrincieli et al., 2019;Retamal-Morales et al., 2021). This is also true for resistance to chromate (Trivedi et al., 2007). ...
Arctic soils are constantly subjected to extreme environmental conditions such as low humidity, strong winds, high salinity, freeze-thaw cycles, UV exposition, and low nutrient availability, therefore, they have developed unique microbial ecosystems. These environments provide excellent opportunities to study microbial ecology and evolution within pristine (i.e. with limited anthropogenic influence) regions since the High Arctic is still considered one of the wildest and least explored environments on the planet. This environment is also of interest for the screening and recovery of unique microbial strains suitable for various biotechnological applications. In this study, a combination of culture-depended and culture-independent approaches was used to determine the cultivation bias in studies of the diversity in cold-active microorganisms. Cultivation bias is a reduction in recovered diversity, introduced when applying a classical culturing technique. Six different soil types, collected in the vicinity of the Polish Polar Station Hornsund (Spitsbergen, Norway), were tested. It was revealed that the used media allowed recovery of only 6.37 % of bacterial and 20 % of fungal genera when compared with a culture-independent approach. Moreover, it was shown that a combination of R2A and Marine Broth media recovered as much as 93.6 % of all cultivable bacterial genera detected in this study. Based on these results, a novel protocol for genome-guided bioprospecting, combining a culture-dependent approach, metabarcoding, next-generation sequencing, and genomic data reuse was developed. With this methodology, 14 psychrotolerant, multi-metal-resistant strains, including the highly promising Rhodococcus spp., were obtained. These strains, besides increased metal tolerance, have a petroleum hydrocarbon utilization capacity, and thus may be good candidates for future bioremediation technologies, also suited to permanently cold regions.
... These acids have low reactivity, which makes the surface of mycobacteria waxy and extremely hydrophobic [74]. According to multiple studies, mycolic acids ensure the resistance of R. erythropolis to various stress factors and pollutants, such as oil products and heavy metals [75][76][77][78][79], and also allow survival on very poor nutrient media [80]. We assume that the presence of a negative effect of NCs on the viability of Cms is associated with the absence of mycolic acids in the cell wall of this bacterium. ...
New promising manganese-containing nanobiocomposites (NCs) based on natural polysaccharides, arabinogalactan (AG), arabinogalactan sulfate (AGS), and κ-carrageenan (κ-CG) were studied to develop novel multipurpose trophic low-dose organomineral fertilizers. The general toxicological effects of manganese (Mn) on the vegetation of potatoes (Solanum tuberosum L.) was evaluated in this study. The essential physicochemical properties of this trace element in plant tissues , such as its elemental analysis and its spectroscopic parameters in electron paramagnetic resonance (EPR), were determined. Potato plants grown in an NC-containing medium demonstrated better biometric parameters than in the control medium, and no Mn accumulated in plant tissues. In addition, the synthesized NCs demonstrated a pronounced antibacterial effect against the phytopathogenic bacterium Clavibacter sepedonicus (Cms) and were proved to be safe for natural soil microflora.
... PAHs are environmental pollutants that easily spread far and wide and are difficult to contain and degrade (Yan et al., 2012). Although physical and chemical treatments, such as photocatalytic oxidation, high-temperature stripping, oxidation-reduction, and solubilization-elution technology, have been used to remove PAHs, the high costs, pollutant residue, and secondary pollution limit their applications (Rani et al., 2020;Chen et al., 2021). Therefore, there is an urgent need to develop effective techniques for PAHs degradation. ...
... The molecular weight of siderophore isolated from Rhodococcus rhodochrous strain OFS is 830 Daltons (Dhungana et al., 2008). Its main role is to bind and solubilize extracellular iron (III) for transport into the cell, satisfying their metabolic requirements (Retamal-Morales et al., 2021). In addition, these compounds play a role in boron transport. ...
A slow degradation rate and low transformation efficiency are the main problems in the biodegradation of polycyclic aromatic hydrocarbons (PAHs). This study selected pyrene as the target PAH to investigate the effect of ferrous ion and ferric ion on pyrene degradation. The driving effect and mechanism, including the interaction between pyrene and iron ions and the bacterial physiological response during the biodegradation process by Rhodococcus ruber strain L9, were investigated. The results showed that iron ions did not enhance bacterial growth but improved bacteria's pyrene removal capacity, contributing to the total efficiency of pyrene biodegradation. The process started with an initial formation of "cation-π" between Fe (III) and pyrene, which subsequently drove the pyrene removal process and accelerated the bacterial metabolic process. Moreover, a significant increase in the protein concentration, catechol dioxygenase (C12O and C23O) activities, and intracellular protein regulation in crude enzyme solution indicate a positive response of the bacteria during the iron ion-enhanced pyrene degradation process.
Aim
Arsenic contamination in agricultural soils poses a serious health risk for humans. Bacteria that produce siderophores, primarily for iron acquisition, can be relevant in combating arsenic toxicity in agricultural soils and simultaneously act as biocontrol agents against plant diseases. We evaluated the arsenic bioremediation and biocontrol potential of the rhizosphere isolate Bacillus amyloliquefaciens BM3 and studied the interaction between the purified siderophore bacillibactin and arsenic.
Methods and Results
BM3 showed high arsenic resistance with (MIC value 475 mM and 24 mM against As(V) and As(III) respectively) and broad spectrum in-vitro antagonism against several phytopathogenic fungi. BM3 was identified by biochemical characterization and 16S rRNA gene sequencing. SEM analysis revealed increased cell size of BM3 when grown in presence of sub-lethal arsenic concentrations. Bioremediation assays showed 74% and 88.1% reduction in As(V) and As(III) concentrations respectively. Genetic determinants for arsenic resistance (arsC and aoxB) and antifungal traits (bacAB and chiA) were detected by PCR. Arsenic chelating ability of bacillibactin, the siderophore purified from culture filtrate of BM3 and identified through spectroscopic data analysis, was observed in CAS assay and fluorescence spectrometry. In-vivo application of talc-based formulation of BM3 in brinjal seedlings showed significant reduction in Fusarium wilt disease.
Conclusion
Strain B. amyloliquefaciens BM3 may be useful in arsenic bioremediation and may be considered for large field trials as an alternative to chemical fungicides by inhibiting soil borne pathogens.
Synthetic fungicides have been the main control of phytopathogenic fungi. However, they cause harm to humans, animals, and the environment, as well as generating resistance in phytopathogenic fungi. In the last few decades, the use of microorganisms as biocontrol agents of phytopathogenic fungi has been an alternative to synthetic fungicide application. Actinomycetes isolated from terrestrial, marine, wetland, saline, and endophyte environments have been used for phytopathogenic fungus biocontrol. At present, there is a need for searching new secondary compounds and metabolites of different isolation sources of actinomycetes; however, little information is available on those isolated from other environments as biocontrol agents in agriculture. Therefore, the objective of this review is to compare the antifungal activity and the main mechanisms of action in actinomycetes isolated from different environments and to describe recent achievements of their application in agriculture. Although actinomycetes have potential as biocontrol agents of phytopathogenic fungi, few studies of actinomycetes are available of those from marine, saline, and wetland environments, which have equal or greater potential as biocontrol agents than isolates of actinomycetes from terrestrial environments.
Siderophore is necessary for the survival of microorganisms and is interregulated with quorum sensing (QS) systems. It is related to growth, proliferation, virulence, and other bacterial social activities as a virulence factor. Thus, we speculated that the QS system could be occluded by inhibiting siderophore production. 2-Hydroxymethyl-1-methyl-5-nitroimidazole (HMMN), one siderophore inhibitor of Pseudomonas aeruginosa PAO1 (P. aeruginosa PAO1), was obtained by using the Chromeazurol S (CAS) method. We found that HMMN inhibited siderophore production and influenced the biological effects of QS regulation, including biofilm formation and pyocyanin production. HMMN (150 μg/ml) inhibited the siderophore production of P. aeruginosa PAO1 by 69.37%. In addition, HMMN could inhibit pyocyanin production and biofilm formation and erase the formed biofilm of P. aeruginosa PAO1. HMMN (150 μg/ml) inhibited the biofilm formation of P. aeruginosa PAO1 by 28.24%. The erasure rate of the formed biofilm reached 17.03%. Furthermore, HMMN (150 μg/ml) inhibited P. aeruginosa PAO1 pyocyanin production by 36.06%. Meanwhile, positive-control hordenine (500.0 μg/ml) reduced the biofilm formation and pyocyanin production of P. aeruginosa PAO1 by 14.42% and 34.35%, respectively. The erasure rate of hordenine to the formed biofilm is 11.05% at 500 μg/ml. Quantitative real-time polymerase chain reaction (qRT-PCR) showed that HMMN downregulates not only siderophore-related genes but also QS-related genes, as well as hordenine. These results suggest that a siderophore inhibitor could be used as a QS inhibitor to occlude the QS system and reduce virulence.
Actinobacteria (Actinomycetes) comprise diverse and ancient phyla of the bacteria with important properties for biotechnology. Large genomes and (mega)plasmids pose a gigantic reservoir of genetic information resulting in interesting and often powerful catabolic and anabolic pathways. Hence, many actinobacteria are able to utilize all kinds of carbon sources and have either evolved specific pathways or perform co-metabolism. In addition, their anabolic capabilities are enormous. Interestingly, natural products, some already being exploited by industries and produced in large amounts, are primary or secondary metabolites of actinobacteria. Among those natural products, the class of siderophores is gaining increasing attention in recent years. These compounds have the ability to coordinate iron or other metal and metalloid ions, earning themselves the name metallophores. Their natural role is to mobilize iron and selected other metal ions to supply the producing and secreting organism with nutrients. Thus, they allow microbes to colonize new habitats or maintain their metabolic activity even under limiting conditions. Siderophores provide access to various applications, and herein, we will highlight and discuss some prominent but also emerging examples, such as phytomining, soil remediation, and medical or imaging applications.
