Inducing Effect of Biosurfactants from Pseudomonas putida 12os Strain on Biodegradation of Hydrocarbons in Oil-Contaminated Soil

Harnessing Biosurfactant-Producing Bacteria from Petroleum-Affected Soils for Environmental and Industrial Applications

The biosurfactant-producing bacteria obtained from oil polluted soils have attracted significant attention due to their ability to enhance the bioavailability of hydrocarbons and to facilitate the remediation of contaminated environments. Several investigations have reported the presence and applications of these microorganisms. However, an overall assessment of their ecological diversity, screening approaches and environmental performance seems limited. The present review critically discusses the diversity of biosurfactant producing bacteria isolated from oil contaminated soils and their functional roles in hydrocarbon degradation and environmental restoration. Special emphasis is placed on the comparative evaluation of commonly employed screening and characterization methods such as drop-collapse, oil-spreading, CTAB agar, emulsification index, microplate and bacterial adhesion to hydrocarbons (BATH) assays. The advantages, limitations and methodological inconsistencies with these techniques in relation to the reliable identification of highly effective bacterial isolates are discussed. This paper reviews recent developments in the application of biosurfactant-producing bacteria for the degradation of petroleum hydrocarbons with a focus on the factors that affect their performance in field conditions. This review encompasses microbial diversity, methodological challenges, and application outcomes, identifying critical knowledge gaps and future priorities for standardization of screening approaches and the development of effective bioremediation strategies. The analysis presented here offers a framework to enhance the utilization of biosurfactant-producing bacteria isolated from oil-polluted soils as sustainable agents for the restoration of the ecosystem.

Characterization of Biosurfactants Produced by a Novel Hydrocarbonoclastic Bacterial Strain Rhodococcus ruber N19 Isolated From River Sediment

The nonhemolytic properties, combined with the ability to lower surface tension and exhibit strong emulsification and oil displacement activities, highlight the potential of this biosurfactant for bioremediation, petroleum industry applications, and biomedical use.

Biosurfactant-mediated degradation of petroleum hydrocarbons by indigenous bacteria from contaminated soil in Hyderabad, India.

Petroleum is a global primary raw material and energy resource. Despite its high economic value and energy density, its usage and extraction cause significant environmental pollution and climate change. Biosurfactants, primarily produced by microorganisms, facilitate the degradation of petroleum hydrocarbons by improving their bioavailability and solubility in the environment. Hence, they are considered as eco-friendly and biodegradable substitutes for bioremediation applications. In the current study, five novel bacterial strains, Rhodococcus sp. strain SARSHI1, Pseudomonas sp. strain SARSHI2, Pseudomonas sp. strain SARSHI3, Acinetobacter sp. strain SARSHI4, and Rhodococcus sp. strain SARSHI5, were isolated, identified, and functionally characterized to evaluate their biosurfactant-producing and hydrocarbon-degrading efficiency. The strains were systematically screened to assess their cell-surface hydrophobicity, biosurfactant activity, emulsification activity, and hydrocarbon-degrading efficiency, etc. Among all the strains, SARSHI1 governed the highest quantitative results by achieving the highest biosurfactant-producing capacity (2.54 g/L), lowest reduced-surface tension (26.87 ± 0.05 mN/m) and CMC (67 mg/L), highest adhesive bioactivity (70.6 ± 2.1%), highest emulsification index (E24 - 81 ± 0.45%), and highest hydrocarbon degradation profile (82% under glycerol supplemented condition). Media optimization analysis revealed the factors for improving the biosurfactant yield at pH 7.0, temperature (30-50 °C), 4% yeast extract, and 4% crude oil concentration. The molecular and taxonomical assessment was conducted by 16S rRNA sequencing, with partial sequences submitted to the GenBank database with unique accession numbers: 'PV034287', 'OP597529', 'OP584476', 'OQ711779', and 'OQ711775' for SARSHI1-SARSHI5, respectively. Lastly, the secondary structure of the 16S rRNA sequences was determined using the UNAFold algorithm. Therefore, the findings of this study present a robust preliminary functional framework for advanced microbial studies and highlight the potential of native bacterial strains for developing economical bioremediation applications to combating petroleum pollution.

Fungal Bioaugmentation and Plant-Based Biostimulation for Petroleum Hydrocarbon Degradation in Mangrove Sediments

Mangrove ecosystems are highly vulnerable to petroleum contamination, with long-lasting environmental consequences due to the persistence of complex hydrocarbon fractions. While bioremediation strategies such as bioaugmentation and biostimulation are widely studied, their comparative effectiveness in mangrove sediments remains poorly understood. This study evaluates the degradation of total petroleum hydrocarbons (TPH) in mangrove sediments contaminated with Recôncavo Basin crude oil (1% w/w) using fungal bioaugmentation (Aspergillus sp.), plant-based biostimulation, and their combination. A controlled mesocosm experiment simulated tidal dynamics over 45 days using 80 bioreactors. Significant reductions in unresolved complex mixture (UCM) and TPH concentrations were observed across all treatments, with UCM reductions reaching up to 78.4% in the biostimulation treatment. However, no statistically significant differences were found among treatments at the end of the experiment (p > 0.05). This suggests a dominant role of intrinsic biodegradation processes, indicating that natural attenuation can be as effective as engineered strategies in specific mangrove environments over the long term. Changes in diagnostic ratios (pristane/phytane and n-alkanes) confirmed the preferential degradation of linear hydrocarbons. These findings highlight the potential of low-cost, nature-based remediation and suggest that intrinsic processes may suffice for long-term recovery, emphasizing the need for extended studies to fully evaluate engineered treatment advantages.

Molecular Analytics of Biosurfactant Producing Bacteria Isolated from Soil

Biosurfactant products show significant potential compared to chemical surfactants due to their biodegradability, low toxicity, and eco-friendliness. This study aims to characterize the structures of biosurfactants produced by bacteria isolated from soil and to evaluate their potential in degrading petrol and oil. Biosurfactant-producing strains were selected using oil spreading tests, screening for petrol-degrading bacteria, antimicrobial susceptibility tests, and PCR-based phylogenetic analysis. In total, 5852 colonies and strains of biosurfactant producers were isolated through cultural and molecular methods. These bacteria were classified into three species: Bacillus, Pseudomonas, and Staphylococcus. After biodegradation, the effects of petrol and olive oil, combined with cell-free supernatant, were analyzed, showing an efficient removal rate of 79.59% after 24 hours. Among the bacterial isolates, three strains demonstrated significant oil degradation capacity: Bacillus sp. With a degradation rate of 79.59%, Pseudomonas sp. At 77.55%, and Staphylococcus sp. At 67.3%. In conclusion, biosurfactant-producing bacteria were isolated from soil samples collected at the Center for Bioscience and Nanoscience Research Laboratory through screening and isolation efforts. 

Ex Situ Bioremediation of PCBs-Contaminated Soils through Microbial Immobilization on Coconut Fiber