Draft genome of Raoultella planticola, a high lead resistance bacterium from industrial wastewater

Genomic insights into the taxonomic status and bioactive gene cluster profiling of Bacillus velezensis RVMD2 isolated from desert rock varnish in Ma'an, Jordan

Extreme environments like arid and semi-arid deserts harbor unique microbial diversity, offering rich sources of specialized microbial metabolites. This study explores Bacillus velezensis RVMD2, a strain isolated from rock varnish in the Ma'an Desert, Jordan. The genome was sequenced using the Illumina NextSeq 2000 platform, resulting in a 4,212,579 bp assembly with a GC content of 45.94%. The assembled genome comprises 112 contigs and encodes 4,250 proteins, 77 tRNA genes, and 4 rRNA genes. Phylogenetic analysis of the 16S rRNA gene indicated a 99.84% similarity to previously identified B. velezensis strains. Whole-genome phylogeny using EzBiome, MiGA, and TYGS confirmed its classification as B. velezensis. Functional annotation identified genes involved in carbohydrate metabolism, including 324 carbohydrate-active enzyme (CAZyme) genes, stress response, and secondary metabolite biosynthesis. The genome also contains 50 genes associated with heavy metal resistance and plant growth promotion. Analysis using AntiSMASH identified 12 biosynthetic gene clusters involved in the production of secondary metabolites, including fengycin, surfactin, polyketides, terpenes, and bacteriocins. Notably, several clusters did not match any known sequences, suggesting the presence of potentially novel antimicrobial compounds. The genomic features of RVMD2 highlight its adaptability to extreme environments and its potential for biotechnological applications, including bioremediation and the discovery of novel bioactive metabolites.

New complete genome insights into Enterobacter roggenkampii FACU2: a potential player in cadmium bio-removal

Industrial workplaces, particularly those involved in ore processing or smelting, pose a high risk of exposure to cadmium, a highly toxic metal. This study isolated and identified eight cadmium-resistant strains from industrial wastewater for their ability to resist cadmium. Enterobacter roggenkampii FACU2 demonstrated exceptional cadmium removal capabilities during our analysis, successfully eliminating 62% of the cadmium. Additionally, transmission electron microscopy (TEM) was utilized to examine the morphological change between the most and least efficient strains that responded to cadmium stress at the cellular level. Compared to the control bacteria, the treated bacteria exhibited notably higher levels of cadmium adsorption and accumulation within their cells. A complete genome analysis revealed that E. roggenkampii FACU2 has one chromosome and one plasmid with a size of 4,856,454 bp and 80,926 bp, respectively, in addition to harboring numerous heavy metal-resistant genes related to cadmium and other heavy metals. Moreover, the gene expression of four cadmium-resistant genes (czcA, cadA, czcC and czcD) showed that the high cadmium concentration led to a significant increase in czcA and cadA mRNA levels, thus indicating the activation of cadmium-resistant genes in the E. roggenkampii FACU2 compared to Enterobacter sp. strain FACU. Due to its ability to remove cadmium and other heavy metals, this strain holds promise as a source of genes for biological treatment methods. This application could contribute to environmental purification, ultimately benefiting human health.

Comparative genomic characterization of Cellulosimicrobium funkei isolate RVMD1 from Ma'an desert rock varnish challenges Cellulosimicrobium systematics

Desert environments harbor unique microbial communities. This study focuses on Cellulosimicrobium funkei isolate RVMD1, isolated from rock varnish in the Ma'an Desert. Initial identification was achieved using 16S rRNA gene sequencing, followed by whole-genome sequencing (WGS) for comprehensive characterization. The genome comprises 4,264,015 base pairs (857 contigs) with a high G + C content of 74.59%. A total of 4,449 proteins were predicted. Comparative analysis utilizing OrthoANI, ANI, AAI, and dDDH metrics suggests that RVMD1 belongs to the C. cellulans group, with the highest similarity to C. funkei (97.71% ANI). Phylogenomic analysis of 43 Cellulosimicrobium genomes revealed significant heterogeneity within the genus. Our results challenge current systematics, with C. cellulans potentially representing up to 9 distinct genomospecies. Isolate RVMD1 shows genetic adaptations to its desert environment, including genes for denitrification, oxygen and sulfur cycling, and diverse hydrogen metabolism. Pangenomic analysis uncovered a considerable number of unique genes within RVMD1, highlighting its genetic distinctiveness. Gene family expansions suggest evolution in response to stressors like UV radiation and nutrient limitation. This study represents the first whole-genome analysis of a bacterium isolated from Jordanian rock varnish, emphasizing the value of WGS in understanding microbial diversity and adaptation in extreme environments.

Hybrid-genome sequence analysis of Enterobacter cloacae FACU and morphological characterization: insights into a highly arsenic-resistant strain

Many organisms have adapted to survive in environments with high levels of arsenic (As), a naturally occurring metalloid with various oxidation states and a common element in human activities. These organisms employ diverse mechanisms to resist the harmful effects of arsenic compounds. Ten arsenic-resistant bacteria were isolated from contaminated wastewater in this study. The most efficient bacterial isolate able to resist 15,000 ppm Na2HAsO4·7H2O was identified using the 16S rRNA gene and whole genome analysis as Enterobacter cloacae FACU. The arsenic E. cloacae FACU biosorption capability was analyzed. To further unravel the genetic determinants of As stress resistance, the whole genome sequence of E. cloacae FACU was performed. The FACU complete genome sequence consists of one chromosome (5.7 Mb) and two plasmids, pENCL 1 and pENCL 2 (755,058 and 1155666 bp, respectively). 7152 CDSs were identified in the E. cloacae FACU genome. The genome consists of 130 genes for tRNA and 21 for rRNAs. The average G + C content was found to be 54%. Sequencing analysis annotated 58 genes related to resistance to many heavy metals, including 16 genes involved in arsenic efflux transporter and arsenic reduction (five arsRDABC genes) and 42 genes related to lead, zinc, mercury, nickel, silver, copper, cadmium and chromium in FACU. Scanning electron microscopy (SEM) confirmed the difference between the morphological responses of the As-treated FACU compared to the control strain. The study highlights the genes involved in the mechanism of As stress resistance, metabolic pathways, and potential activity of E. cloacae FACU at the genetic level.

Omics technology draws a comprehensive heavy metal resistance strategy in bacteria

The rapid industrial revolution significantly increased heavy metal pollution, becoming a major global environmental concern. This pollution is considered as one of the most harmful and toxic threats to all environmental components (air, soil, water, animals, and plants until reaching to human). Therefore, scientists try to find a promising and eco-friendly technique to solve this problem i.e., bacterial bioremediation. Various heavy metal resistance mechanisms were reported. Omics technologies can significantly improve our understanding of heavy metal resistant bacteria and their communities. They are a potent tool for investigating the adaptation processes of microbes in severe conditions. These omics methods provide unique benefits for investigating metabolic alterations, microbial diversity, and mechanisms of resistance of individual strains or communities to harsh conditions. Starting with genome sequencing which provides us with complete and comprehensive insight into the resistance mechanism of heavy metal resistant bacteria. Moreover, genome sequencing facilitates the opportunities to identify specific metal resistance genes, operons, and regulatory elements in the genomes of individual bacteria, understand the genetic mechanisms and variations responsible for heavy metal resistance within and between bacterial species in addition to the transcriptome, proteome that obtain the real expressed genes. Moreover, at the community level, metagenome, meta transcriptome and meta proteome participate in understanding the microbial interactive network potentially novel metabolic pathways, enzymes and gene species can all be found using these methods. This review presents the state of the art and anticipated developments in the use of omics technologies in the investigation of microbes used for heavy metal bioremediation.

Draft genome analysis for Enterobacter kobei, a promising lead bioremediation bacterium

Lead pollution of the environment poses a major global threat to the ecosystem. Bacterial bioremediation offers a promising alternative to traditional methods for removing these pollutants, that are often hindered by various limitations. Our research focused on isolating lead-resistant bacteria from industrial wastewater generated by heavily lead-containing industries. Eight lead-resistant strains were successfully isolated, and subsequently identified through molecular analysis. Among these, Enterobacter kobei FACU6 emerged as a particularly promising candidate, demonstrating an efficient lead removal rate of 83.4% and a remarkable lead absorption capacity of 571.9 mg/g dry weight. Furthermore, E. kobei FACU6 displayed a remarkable a maximum tolerance concentration (MTC) for lead reaching 3,000 mg/L. To further investigate the morphological changes in E. kobei FACU6 in response to lead exposure, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed. These analyses revealed significant lead adsorption and intracellular accumulation in treated bacteria in contrast to the control bacterium. Whole-genome sequencing was performed to gain deeper insights into E. kobei's lead resistance mechanisms. Structural annotation revealed a genome size of 4,856,454 bp, with a G + C content of 55.06%. The genome encodes 4,655 coding sequences (CDS), 75 tRNA genes, and 4 rRNA genes. Notably, genes associated with heavy metal resistance and their corresponding regulatory elements were identified within the genome. Furthermore, the expression levels of four specific heavy metal resistance genes were evaluated. Our findings revealed a statistically significant upregulation in gene expression under specific environmental conditions, including pH 7, temperature of 30°C, and high concentrations of heavy metals. The outstanding potential of E. kobei FACU6 as a source of diverse genes related to heavy metal resistance and plant growth promotion makes it a valuable candidate for developing safe and effective strategies for heavy metal disposal.

Genomic Landscape of Multidrug Resistance and Virulence in Enterococcus faecalis IRMC827A from a Long-Term Patient

We report on a highly virulent, multidrug-resistant strain of Enterococcus faecalis IRMC827A that was found colonizing a long-term male patient at a tertiary hospital in Khobar, Saudi Arabia. The E. faecalis IRMC827A strain carries several antimicrobial drug resistance genes and harbours mobile genetic elements such as Tn6009, which is an integrative conjugative element that can transfer resistance genes between bacteria and ISS1N via an insertion sequence. Whole-genome-sequencing-based antimicrobial susceptibility testing on strains from faecal samples revealed that the isolate E. faecalis IRMC827A is highly resistant to a variety of antibiotics, including tetracycline, doxycycline, minocycline, dalfopristin, virginiamycin, pristinamycin, chloramphenicol, streptomycin, clindamycin, lincomycin, trimethoprim, nalidixic acid and ciprofloxacin. The isolate IRMC827A carries several virulence factors that are significantly associated with adherence, biofilm formation, sortase-assembled pili, manganese uptake, antiphagocytosis, and spreading factor of multidrug resistance. The isolate also encompasses two mutations (G2576T and G2505A) in the 23S rRNA gene associated with linezolid resistance and three more mutations (gyrA p.S83Y, gyrA p.D759N and parC p.S80I) of the antimicrobial resistance phenotype. The findings through next-generation sequencing on the resistome, mobilome and virulome of the isolate in the study highlight the significance of monitoring multidrug-resistant E. faecalis colonization and infection in hospitalized patients. As multidrug-resistant E. faecalis is a serious pathogen, it is particularly difficult to treat and can cause fatal infections. It is important to have quick and accurate diagnostic tests for multidrug-resistant E. faecalis, to track the spread of multidrug-resistant E. faecalis in healthcare settings, and to improve targeted interventions to stop its spread. Further research is necessary to develop novel antibiotics and treatment strategies for multidrug-resistant E. faecalis infections.

Biodegradation of isoproturon by Escherichia coli expressing a Pseudomonas putida catechol 1,2-dioxygenase gene

The phenylurea herbicides are persistent in soil and water, necessitating the creation of methods for removing them from the environment. This study aimed to examine the soil microbial diversity, searching for local bacterial isolates able to efficiently degrade the phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1, 1-dimethylurea (IPU). The best isolates able to effectively degrade IPU were selected, characterized, and identified as Pseudomonas putida and Acinetobacter johnsonii. The catechol 1, 2-dioxygenase enzyme's catA gene was amplified, cloned, and expressed in E. coli M15. The Expressed E. coli showed high degradation efficiency (44.80%) as analyzed by HPLC after 15 days of inoculation in comparison to P. putida (21.60%). The expression of the catA gene in P. putida and expressed E. coli was measured using quantitative polymerase chain reaction (qPCR). The results displayed a significant increase in the mRNA levels of the catA gene by increasing the incubation time with IPU. Hydrophilic interaction chromatography (HILIC) mass spectrometry analysis revealed that three intermediate metabolites, 1-(4-isopropylphenyl)-3-methylurea (MDIPU), 4-Isopropylaniline (4-IA) and 1-(4-isopropylphenyl) urea (DDIPU) were generated by both P. putida and expressed E. coli. In addition, IPU-induced catA activity was detected in both P. putida and expressed E. coli. The supernatant of both P. putida and expressed E. coli had a significant influence on weed growth. The study clearly exhibited that P. putida and expressed E. coli were capable of metabolizing IPU influentially and thus could be utilized for bioremediation and biodegradation technology development.