Isolation, Molecular Characterization, and Screening for Hydrocarbon-degrading Potential of an Indigenous Enterobacter sp. from Petroleum-contaminated Soil for Bioremediation Applications
Aug 2026· Journal of Advances in Microbiology· 0 citations
TL;DR
The results indicate that indigenous bacteria from chronically hydrocarbon-contaminated soils can show differing relative activities under the screening conditions, with K2 displaying the strongest response among the isolates tested.
Abstract
Petroleum hydrocarbon contamination creates ecological risks and motivates sustainable remediation strategies. This study isolated indigenous oil-degrading bacteria from petroleum-contaminated soils and screened their relative hydrocarbon-degrading potential. Four soil samples were collected from automobile-workshop sites in and around Bengaluru and Chikkaballapur, Karnataka, India. Samples were enriched in Bushnell–Haas minimal salt medium supplemented with 3% (v/v) used engine oil as the sole carbon source. Eight isolates were obtained and screened using an agar well diffusion clearance-zone assay. Morphological and biochemical characterisation was followed by 16S rRNA gene sequencing of the most active isolate. Isolate K2 produced the largest clearance zone (30 mm), followed by C2 (25 mm) and K3 (20 mm), whereas W1 and S1 produced 5 mm zones. BLASTn and phylogenetic analysis placed K2 within the Enterobacter cloacae complex, with 99.93% sequence identity to reference sequences in GenBank. The results indicate that indigenous bacteria from chronically hydrocarbon-contaminated soils can show differing relative activities under the screening conditions, with K2 displaying the strongest response among the isolates tested. Because the agar well diffusion assay does not directly quantify hydrocarbon removal, the observed clearance zones should be interpreted as a relative screening measure. Quantitative gravimetric or chromatographic analyses, together with soil-based validation, are required before the degradation efficiency and bioremediation applicability of K2 can be established.
The studied strains possess a number of properties that promote plant growth: they produce auxins, solubilize calcium hydroxyapatite, and protect plants from infection by the phytopathogenic microorganisms Fusarium oxysporum and Pectobacterium wasabiae.
R. Narmanova, Y. Delegan, Olga Mironova et al.· Environments· 0 citations
Petroleum contamination is a prevalent environmental issue, with detrimental effects extending across diverse ecosystems. Among the numerous hydrocarbons present in petroleum, diesel is a major contributor to soil pollution. Previous studies have identified bacteria as highly effective agents for diesel degradation (DD), highlighting their potential for bioremediation of oil spills. However, successful bioremediation of diesel-contaminated environments requires the identification of effective diesel-degrading microbial strains, along with key traits that support DD, such as biosurfactant production. Therefore, this study aimed to identify efficient diesel-degrading bacteria (DDB) from petroleum-contaminated sites in Kandy District, while concurrently exploring their biosurfactant production capabilities. DDB were isolated using Bushnell-Haas broth supplemented with diesel. Pure bacterial isolates were obtained by streak and spread plating techniques. Isolated bacteria were identified through morphological and biochemical methods. The DD efficiencies of the isolates were examined by turbidity assay and 2,6-dicholophenolindophenol (DCPIP) assays. Moreover, efficient DDB were used to design artificial consortia. The degradation efficiencies of artificial consortia and natural consortia were also evaluated. Additionally, the biosurfactant production ability of efficient DDB was investigated by the emulsification test, oil displacement test, and CTAB agar plates. Among the diesel-degrading bacterial strains isolated, the four most effective isolates, in the order of decreasing efficiency, belonged to the genera Pseudomonas (83.04%), Staphylococcus (71.84%), Corynebacterium (62.61%), and Streptococcus (60.50%). Further, the DD efficiencies of most of the designed consortia and natural consortia were found to be significantly higher than those of the individual bacterial isolates, with one natural consortium containing Pseudomonas, Staphylococcus, and Corynebacterium that outperformed the designed consortia. Moreover, the isolated Pseudomonas and Staphylococcus strains were identified as biosurfactant producers, suggesting that their ability to produce biosurfactants contributes to their highest DD efficiencies. The findings of this study can be used in developing locally adaptable bioremediation strategies for diesel-contaminated sites in Sri Lanka.
K. Hansani, P. Samaraweera· Ceylon Journal of Science· 0 citations
Findings highlight the potential biotechnological relevance of culturable bacterial isolates recovered from historically mining-impacted soils and provide genomic resources for future studies on environmental remediation, sustainable agriculture, and industrial biotechnology.
M. J. Puy-Alquiza, B. N. Luna, Lorena Rodríguez Orduña et al.· Geomicrobiology Journal· 0 citations
Heavy metal contamination arising from municipal, industrial, and biomedical waste disposal has emerged as a major environmental concern, contributing not only to ecosystem degradation but also to the co-selection and dissemination of antimicrobial resistance among environmental microorganisms. The present study aimed to isolate, characterize, and molecularly identify an antibiotic- and heavy metal-resistant (AHMR) bacterium from contaminated solid waste disposal sites in West Bengal, India, and to evaluate its potential for bioremediation of heavy metal-polluted environments. Soil samples collected from hospital, industrial, and municipal waste disposal sites were screened on nutrient agar supplemented with nickel (Ni), lead (Pb), and cadmium (Cd) (50 µg mL⁻¹), resulting in the recovery of seven morphologically distinct bacterial isolates. Antibiotic susceptibility profiling using the Kirby–Bauer disc diffusion method identified isolate S23 as the most resistant strain, exhibiting a multidrug resistance (MDR) index of 0.8 with resistance to gentamicin, tetracycline, penicillin, and amphotericin B. Heavy metal tolerance assays demonstrated a minimum inhibitory concentration (MIC) of approximately 100 µg mL⁻¹ for all three metals, with nickel producing the strongest inhibitory effect on bacterial growth. Physiological and biochemical characterization revealed that isolate S23 was a mesophilic, halotolerant, catalase-positive bacterium capable of utilizing multiple carbohydrates, including glucose and sucrose. Growth kinetics further demonstrated its ability to maintain sustained proliferation under heavy metal stress, indicating a high degree of environmental adaptability. Molecular identification based on 16S rRNA gene sequencing confirmed the isolate as Aeromonas hydrophila. The concurrent occurrence of multidrug antibiotic resistance and heavy metal tolerance supports the hypothesis of co-selection of resistance determinants in contaminated environments. Furthermore, the remarkable metal tolerance exhibited by A. hydrophila suggests its potential application in the bioremediation of heavy metal-contaminated soils and wastewater through mechanisms such as biosorption, bioaccumulation, and biotransformation. Overall, this study highlights the ecological significance of environmental A. hydrophila as a resilient microorganism with promising applications in sustainable remediation strategies while emphasizing the environmental role of polluted habitats as reservoirs for multidrug-resistant bacteria
Pritam Paul, Ankana chatterjee, Banhishikha Singh et al.· World Journal of Advanced Re...· 0 citations
Hydrolases are enzymes with broad industrial applications across the food, pharmaceutical, textile, detergent, and paper sectors. For commercial use, these enzymes are primarily sourced from microorganisms. Halophilic bacteria, which thrive in high-salinity environments, represent a promising yet underutilized source of novel hydrolases. This study aimed to isolate and screen halophilic bacteria from mangrove soil in Sumberkima Village, Buleleng Regency, Bali Province, Indonesia, for their ability to produce extracellular hydrolases. Soil samples were cultivated on Luria-Bertani (LB) media supplemented with 5% and 10% (w/v) NaCl. Putative colonies were isolated and screened for amylase, cellulase, and lipase production using starch, carboxymethyl cellulose, and rhodamine-olive oil agar, respectively. Enzymatic activities were quantified via spectrophotometry, and the most proficient isolates were identified through 16S rRNA gene phylogenetic analysis. The screening yielded several halophilic bacteria with significant extracellular hydrolase activity. The most proficient isolates identified were: amylase-producing Vibrio xiamenensis SKMG1(4) (0.44 U/mL), cellulase-producing Vibrio hepatarius SKMG1(3) (0.36 U/mL), and lipase-producing Salinivibrio kushneri SKMG2(5) (21.6 U/mL). Phylogenetic analysis confirmed the close taxonomic relationship of these isolates to their respective type strains. This study represents the first report of extracellular hydrolase production from these three halophilic bacterial species, highlighting their potential for specialized industrial applications.
I. P. Parwata, Siti Maryam, I. Nyoman Tika· Molekul· 0 citations
Petroleum-impacted soils containing total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs) restrict land reuse and pose long-term threats to soil productivity and food security in oil-producing regions. This study evaluates the performance of mutually adapted bacterial–fungal consortia comprising Pseudomonas aeruginosa, Azotobacter vinelandii, and Aspergillus niger, with targeted NPK nutrient amendments, for accelerating hydrocarbon removal and restoring soil function for post-remediation agricultural use.
Simulated crude-oil-polluted soils (SCOPs) were treated under controlled soil glass columns (2.5 cm × 3.2 cm) at 30 ± 2 °C over 21- and 42-day periods. Microbial inocula were standardised at 1.5 × 108 cells cm−3. Nine treatment configurations evaluated live/inactive consortium members under bioaugmentation (BA) and combined bioaugmentation–biostimulation (BA+BS) conditions. TPH and PAH concentrations were quantified by GC-FID following n-hexane/dichloromethane extraction, and soil protein content served as a proxy for microbial biomass and soil quality recovery. First-order kinetic modelling and regression analysis were applied to all treatment groups. First-order kinetic modelling and Duncan's Multiple Range Test (DMRT) revealed that the ternary consortium featuring Live P. aeruginosa + Dead A. vinelandii + Live A. niger (Group A9/B9) achieved the highest overall bioremediation performance. This arrangement drove an 83.0% reduction in TPH (from 794.9 mg/kg to 138.5 mg/kg; k = 0.0416 d−1, t1/2 = 16.6 days) and a 76.4% reduction in PAHs (75.7 mg/kg to 17.9 mg/kg; k = 0.0343 d−1, t1/2 = 20.2 days), statistically outperforming biostimulated binary controls (P < 0.05). Soil protein concentration correlated positively with cumulative hydrocarbon removal (R2 = 0.71–0.89 across, p < 0.005 for BA+BS groups), confirming protein as a reliable activity indicator.
The study proposes an operational bioremediation framework incorporating consortium selection, staged nutrient dosing, pH control, moisture and aeration management, and dual GC-FID/protein monitoring. Findings demonstrate that optimised microbial co-metabolism can shorten remediation timelines, lower environmental footprint and cost relative to physicochemical treatments, and measurably restore soil functions supporting post-remediation agricultural reuse and food security in oil-impacted regions.
C. P. Chinedu, Cynthia Chinonso Etoruom, Nnaemeka Emmanuel Uhuo et al.· SPE Nigeria Annual Internati...· 0 citations
