Degradation of hydrocarbons and biosurfactant production by Pseudomonas sp. strain LP1

Molecular identification of rhamnolipids produced by Pseudomonas oryzihabitans during biodegradation of crude oil

Introduction

The ability to produce biosurfactants plays a meaningful role in the bioavailability of crude oil hydrocarbons and the bioremediation efficiency of crude oil-degrading bacteria. This study aimed to characterize the produced biosurfactants by Pseudomonas oryzihabitans during the biodegradation of crude oil hydrocarbons.

Methods

The biosurfactants were isolated and then characterized by Fourier transform infrared (FTIR), liquid chromatography-mass-spectrometry (LC-MS), and nuclear magnetic resonance spectroscopy (NMR) analyses.

Results

The FTIR results revealed the existence of hydroxyl, carboxyl, and methoxyl groups in the isolated biosurfactants. Also, the LC-MS analysis demonstrated a main di-rhamnolipid (l-rhamnopyranosyll-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoate, Rha-Rha-C10-C10) along with a mono-rhamnolipid (l-rhamnopyranosyl-b-hydroxydecanoylb-hydroxydecanoate, Rha-C10-C10). In agreement with these findings, the NMR analysis confirmed the aromatic, carboxylic, methyl, sulfate moieties, and hexose sugar in the biosurfactants. The emulsion capacity of the biosurfactants decreased the surface tension of the aqueous system from 73.4 mN m-1 to around 33 mN m-1 at 200 mg L-1 as the critical micelle concentration. The emulsification capacity of the biosurfactants in the formation of a stable microemulsion for the diesel-water system at a wide range of pH (2-12), temperature (0-80°C), and salinity (2-20 g L-1 of NaCl) showed their potential use in oil recovery and bioremediation through the use of microbial enhancement.

Discussion

This work showed the ability of Pseudomonas oryzihabitans NC392 cells to produce rhamnolipid molecules during the biodegradation process of crude oil hydrocarbons. These biosurfactants have potential in bioremediation studies as eco-friendly and biodegradable products, and their stability makes them optimal for areas with extreme conditions.

Glycolipids biosurfactants production using low-cost substrates for environmental remediation: progress, challenges, and future prospects

The production of renewable materials from alternative sources is becoming increasingly important to reduce the detrimental environmental effects of their non-renewable counterparts and natural resources, while making them more economical and sustainable. Chemical surfactants, which are highly toxic and non-biodegradable, are used in a wide range of industrial and environmental applications harming humans, animals, plants, and other entities. Chemical surfactants can be substituted with biosurfactants (BS), which are produced by microorganisms like bacteria, fungi, and yeast. They have excellent emulsifying, foaming, and dispersing properties, as well as excellent biodegradability, lower toxicity, and the ability to remain stable under severe conditions, making them useful for a variety of industrial and environmental applications. Despite these advantages, BS derived from conventional resources and precursors (such as edible oils and carbohydrates) are expensive, limiting large-scale production of BS. In addition, the use of unconventional substrates such as agro-industrial wastes lowers the BS productivity and drives up production costs. However, overcoming the barriers to commercial-scale production is critical to the widespread adoption of these products. Overcoming these challenges would not only promote the use of environmentally friendly surfactants but also contribute to sustainable waste management and reduce dependence on non-renewable resources. This study explores the efficient use of wastes and other low-cost substrates to produce glycolipids BS, identifies efficient substrates for commercial production, and recommends strategies to improve productivity and use BS in environmental remediation.

Simultaneous removal of aliphatic and aromatic crude oil hydrocarbons by Pantoea agglomerans isolated from petroleum-contaminated soil in the west of Iran

Hydrocarbons are considered as one of the most common and harmful environmental pollutants affecting human health and the environment. Bioremediation as an environmentally friendly, highly efficient, and cost-effective method in remediating oil-contaminated environments has been interesting in recent decades. In this study, hydrocarbon degrader bacterial strains were isolated from the highly petroleum-contaminated soils in the Dehloran oil field in the west of Iran. Out of 37 isolates, 15 can grow on M9 agar medium that contains 1.5 g L-1 of crude oil as the sole carbon source. The morphological, biochemical, and 16SrRNA sequencing analyses were performed for the isolates. The choosing of the isolates as the hydrocarbon degrader was examined by evaluating the efficacy of their crude oil removal at a concentration of 10 g L-1 in an aqueous medium. The results showed that five isolates belonging to Pseudomonas sp., Pseudomonas oryzihabitans, Roseomonas aestuarii, Pantoea agglomerans, and Arthrobacter sp. had a hyper hydrocarbon-degrading activity and they could remove more than 85% of the total petroleum hydrocarbon (TPH) after 96 h. The highest TPH removal of about 95.75% and biodegradation rate of 0.0997 g L-1 h-1 was observed for P. agglomerans. The gas chromatography-mass spectroscopy (GC-MS) analysis was performed during the biodegradation process by P. agglomerans to detect the degradation intermediates and final products. The results confirmed the presence of intermediates such as alcohols and fatty acids in the terminal oxidation pathway of alkanes in this biodegradation process. A promising P. agglomerans NB391 strain can remove aliphatic and aromatic hydrocarbons simultaneously.

Recent advances in microbial engineering approaches for wastewater treatment: a review

In the present era of global climate change, the scarcity of potable water is increasing both due to natural and anthropogenic causes. Water is the elixir of life, and its usage has risen significantly due to escalating economic activities, widespread urbanization, and industrialization. The increasing water scarcity and rising contamination have compelled, scientists and researchers, to adopt feasible and sustainable wastewater treatment methods in meeting the growing demand for freshwater. Presently, various waste treatment technologies are adopted across the globe, such as physical, chemical, and biological treatment processes. There is a need to replace these technologies with sustainable and green technology that encourages the use of microorganisms since they have proven to be more effective in water treatment processes. The present review article is focused on demonstrating how effectively various microbes can be used in wastewater treatment to achieve environmental sustainability and economic feasibility. The microbial consortium used for water treatment offers many advantages over pure culture. There is an urgent need to develop hybrid treatment technology for the effective remediation of various organic and inorganic pollutants from wastewater.

Bio-mediated detoxification of heavy metal contaminated soil and phytotoxicity reduction using novel strain of Brevundimonas vancanneytii SMA3

Heavy metals pose a serious environmental threat on a global scale due to their toxicity towards livings. Therefore, removing harmful metals from the environment has become more challenging in recent years. The objective of this study is to isolate, examine, and characterize naturally existing bacteria that possess the ability to mitigate and detoxify heavy metals such as cadmium, mercury, and lead. The selected bacteria SMA3 actively demonstrated metal tolerance during screening and was then employed for biosorption study using a lab-scale technique. The bacterium belonged to Brevundimonas sp., according to 16 S rRNA analysis. To enhance the removal efficiency of SMA3, response surface methodology (RSM) was employed, resulting in the identification of optimized conditions (pH 7, temperature 30 °C and shaking speed 120 rpm) for achieving maximum removal percentage (69.5 % of Cd, 58.6 % of Hg, and 85.1 % of Pb) within 72 h. The structural changes induced by microbial treatment were demonstrated by comparing the findings of FESEM images and FTIR spectra confirming the disappearance of C ^ C, C]O peaks along with C]O, C-O-C, C-H, and O-H bond destabilization following bioaccumulation. Moreover, in terms of phytotoxicity evaluation, it was observed that the treated soil, containing both heavy metals and the selected potent bacterial strain, exhibited reduced toxicity, resulting in improved germination and growth parameters for the seeds of Solanum lycopersicum (tomato plant). Overall, the selected bacterial strain demonstrated its potential for effectively removing multiple metals from the metal contaminated environment.

Two-step conversion of polyethylene into recombinant proteins using a microbial platform

BACKGROUND

The increasing prevalence of plastic waste combined with the inefficiencies of mechanical recycling has inspired interest in processes that can convert these waste streams into value-added biomaterials. To date, the microbial conversion of plastic substrates into biomaterials has been predominantly limited to polyhydroxyalkanoates production. Expanding the capabilities of these microbial conversion platforms to include a greater diversity of products generated from plastic waste streams can serve to promote the adoption of these technologies at a larger scale and encourage a more sustainable materials economy.

RESULTS

Herein, we report the development of a new strain of Pseudomonas bacteria capable of converting depolymerized polyethylene into high value bespoke recombinant protein products. Using hexadecane, a proxy for depolymerized polyethylene, as a sole carbon nutrient source, we optimized media compositions that facilitate robust biomass growth above 1 × 109 cfu/ml, with results suggesting the benefits of lower hydrocarbon concentrations and the use of NH4Cl as a nitrogen source. We genomically integrated recombinant genes for green fluorescent protein and spider dragline-inspired silk protein, and we showed their expression in Pseudomonas aeruginosa, reaching titers of approximately 10 mg/L when hexadecane was used as the sole carbon source. Lastly, we demonstrated that chemically depolymerized polyethylene, comprised of a mixture of branched and unbranched alkanes, could be converted into silk protein by Pseudomonas aeruginosa at titers of 11.3 ± 1.1 mg/L.

CONCLUSION

This work demonstrates a microbial platform for the conversion of a both alkanes and plastic-derived substrates to recombinant, protein-based materials. The findings in this work can serve as a basis for future endeavors seeking to upcycle recalcitrant plastic wastes into value-added recombinant proteins.

Biodegradation of Petroleum Sludge by Methylobacterium sp. Strain ZASH

A bacterium was isolated from sludge-contaminated soil in a petroleum refinery and tested for its ability to degrade aliphatic hydrocarbon compounds present in petroleum sludge. The isolate was grown on minimal salt media agar supplemented with 1% (w/v) petroleum sludge. The isolate was tentatively identified as Methylobacterium s p. s t rain ZASH based on the partial 16s rDNA molecular phylogeny. The bacterium grew optimally between the temperatures of 30°C and 35°C, pH 7 and 7.5, 0.5% and 1.5% (v/v) Tween 80 as the surfactant, and between 1% and 2% (w/v) peptone as the nitrogen source. The constants derived from the Haldane equation were μmax = 0.039 hr-1, Ks = 0.385% (w/v) total petroleum hydrocarbons (TPH) or 3,850 mg/L TPH, and Ki =1.12% (w/v) TPH or 11,200 mg/L. The maximum biodegradation rate exhibited by this strain was 19 mg/L/hr at an initial TPH concentration of 10,000 mg/L. Gas chromatography analysis revealed that after 15 days the strain was able to degrade all aliphatic n-alkanes investigated with different efficiencies. Shorter n-alkanes were generally degraded more rapidly than longer n-alkanes with 90% removal for C-12 compared to only 30% removal for C-36. The addition of sawdust did not improve bacterial degradation of petroleum hydrocarbons, but it assisted in the removal of remaining undegraded hydrocarbons through adsorption.

Heavy metals assessment of ecosystem polluted with wastewaters and taxonomic profiling of multi-resistant bacteria with potential for petroleum hydrocarbon catabolism in nitrogen-limiting medium

The coexistence of heavy metals (HMs) and petroleum hydrocarbons (PHs) exacerbates ecotoxicity and impair the drivers of eco-functionalities that stimulate essential nutrients for the productivity of the impacted environment. Profiling the bacteria that stem the ecological impact via HMs sequestration and PHs catabolism with nitrogen fixation is imperative to bioremediation of the polluted sites. The sediment of site that was consistently contaminated with industrial wastewaters was analysed for ecological toxicants and the bacterial strains that combined HMs resistance with PHs catabolism in a nitrogen-limiting system were isolated from the sediment and characterized. The geochemistry of the samples revealed the co-occurrence of the above-benchmark concentrations of HMs with the derivatives of hydrocarbons. Notwithstanding, nickel and mercury (with 5% each of the total metal concentrations in the polluted site) exhibited probable effect concentrations on the biota and thus hazardous to the ecosystem. Approx. 31% of the bacterial community, comprising unclassified Planococcaceae, unclassified Bradyrhizobiaceae, Rhodococcus, and Bacillus species, resisted 160 µmol Hg²⁺ in the nitrogen-limiting system within 24 h post-inoculation. The bacterial strains adopt volatilization, and sometimes in combination with adsorption/bioaccumulation strategies to sequester Hg²⁺ toxicity while utilizing PHs as sources of carbon and energy. Efficient metabolism of petroleum biomarkers (> 87%) and Hg²⁺ sequestration (≥ 75% of 40 µmol Hg²⁺) displayed by the selected bacterial strains portend the potential applicability of the bacilli for biotechnological restoration of the polluted site.

Biosynthesis and chemical composition of nanomaterials in agricultural soil bioremediation: a review

Nanomaterials (NMs) are currently being used in agricultural soils as part of a new bioremediation (BR) process. In this study, we reviewed the biosynthesis of NMs, as well as their chemical composition and prospective strategies for helpful and sustainable agricultural soil bioremediation (BR). Different types of NMs, such as nanoparticles, nanocomposites, nanocrystals, nano-powders, and nanotubes, are used in agricultural soil reclamation, and they reflect the toxicity of NMs to microorganisms. Plants (Sargassum muticum, Dodonaea viscose, Aloe Vera, Rosemarinus officinalis, Azadirachta indica, Green tea, and so on) and microorganisms (Escherichia coli, Shewanella oneidensis, Pleurotus sp., Klebsiella oxytoca, Aspergillus clavatus, and so on) are the primary sources for the biosynthesis of NMs. By using the BR process, microorganisms, such as bacteria and plants, can immobilize metals and change both inorganic and organic contaminants in the soil. Combining NMs with bioremediation techniques for agricultural soil remediation will be a valuable long-term solution.

Microbial surfactants: A journey from fundamentals to recent advances

Microbial surfactants are amphiphilic surface-active substances aid to reduce surface and interfacial tensions by accumulating between two fluid phases. They can be generically classified as low or high molecular weight biosurfactants based on their molecular weight, whilst overall chemical makeup determines whether they are neutral or anionic molecules. They demonstrate a variety of fundamental characteristics, including the lowering of surface tension, emulsification, adsorption, micelle formation, etc. Microbial genera like Bacillus spp., Pseudomonas spp., Candida spp., and Pseudozyma spp. are studied extensively for their production. The type of biosurfactant produced is reliant on the substrate utilized and the pathway pursued by the generating microorganisms. Some advantages of biosurfactants over synthetic surfactants comprise biodegradability, low toxicity, bioavailability, specificity of action, structural diversity, and effectiveness in harsh environments. Biosurfactants are physiologically crucial molecules for producing microorganisms which help the cells to grasp substrates in adverse conditions and also have antimicrobial, anti-adhesive, and antioxidant properties. Biosurfactants are in high demand as a potential product in industries like petroleum, cosmetics, detergents, agriculture, medicine, and food due to their beneficial properties. Biosurfactants are the significant natural biodegradable substances employed to replace the chemical surfactants on a global scale in order to make a cleaner and more sustainable environment.

Potential Application of Biosurfactant-Producing Bacteria for Bioremediation of Oil Polluted Marine Intertidal Sediments

The removal of oil contaminants in marine intertidal sediments under cold climate is an urgent issue. Although the bioavailability of petroleum hydrocarbons decreases at low temperatures, biosurfactants can promote oil biodegradation. In this study, characteristics of biosurfactants produced by cold-adapted oil-degrading bacteria Planococcus sp. XW-1 were studied. Adding the XW-1 biosurfactant could effectively facilitate the solubility of phenanthrene, pyrene, diesel oil, and crude oil. The solubilization was limited by the number of rings and the molecular weight (WSRphenanthrene = 0.0234; WSRpyrene = 0.0165; WSRdiesel oil = 0.0027; WSRcrude oil = 0.0015). Additional biosurfactants significantly washed out crude oil adsorbed to the sand (reduction from 17.1%, 22.7% to 87.9% and 94.28% in 24 h). With the increase in particle size, the removal efficiency increased from 87.9% to 94.28%. After the addition of biosurfactant, the effect of degradation increased by 20% in 20 days. The results suggest that the biosurfactant-producing bacteria Planococcus sp. XW-1 is a promising candidate used in the in situ bioremediation of petroleum-contaminated intertidal sediment.

Adaptive changes of sediment microbial communities associated with cleanup of oil spills in Nigerian mangrove forests

The objectives of this study were to assess the influence on microbial communities resulting from i) the physical removal of free oil (pre-treatment or post-treatment), and ii) the level of oiling within a contaminated former mangrove forest. Sediment samples were collected before and after the removal of free oil. Before the process of remediation, a highly biodiverse mangrove microbiome which had adapted to history of recurring oil spills was observed. After removing the surface oil, the microbial diversity of the sediments reduced, with members of the phyla Firmicutes and Proteobacteria becoming dominant. This indicates that while water flushing reduced overall microbial diversity, it stimulated the growth of a more specialized bacterial community reported to be involved in hydrocarbon biodegradation. These results provide new insights on microbial communities and their succession in mangrove forest sediments, that will be useful for monitoring oil cleaning programs using water flushing to remove free oil.

Improving the bioremediation technology of contaminated wastewater using biosurfactants produced by novel bacillus isolates

Biosurfactants have many advantages outside chemical one, led for application it through different sectors. So, the present study aimed for improving the bioremediation technology of contaminated wastewater using biosurfactants produced by novel bacillus isolates. In this regard, Bacillus thuringiensis and Bacillus toyonensis strains were obtained as most producing isolates of highly active biosurfactants. The optimized conditions for high biosurfactants yield production were established. Also, the stability of the produced biosurfactants at various conditions, pH, temperature and salinity was studied. The biosurfactant has been reported up to 120 °C, pH 12 and 10% of NaCl. The identified biosurfactants, decanoic acid and oleamide were applied for wastewater remediation from oil residues and pathogens contamination. The biosurfactant was had high antibacterial activity compared with references antimicrobial drugs, as well as it is enhanced bioremediation technology for petroleum oil residues contaminating sites. Thus, we can say, these biosurfactants could achieve the objectives of sustainable development.

Ecological risk potentials of petroleum hydrocarbons and heavy metals shape the bacterial communities of marine hydrosphere at Atlantic Ocean, Atlas Cove, Nigeria

Trans-Atlantic voyage of petroleum often leads to marine pollution with petroleum hydrocarbons (PHs) and heavy metals (HMs) that defines structures of autochthonous bacteria in the hydrosphere. Bacterial taxa of marine sediments exposed to petroleum transport activities were profiled using 16S rDNA metagenomics and correlated with the geochemistry to establish their impact on the microbiome. The physico-chemistry of the marine systems revealed varied degrees of contamination with PHs and HMs exceeding recommended threshold for aquatic life. Ecological risk assessment based on organic carbon of the sediment established phenanthrene, anthracene, and pyrene posed high risks (index risk quotient >32) to marine life. The most dominant phylum of the 44 bacterial phyla in the marine-sphere was Proteobacteria with relative abundance of 45-77% in the sampling locations. Relative dominance of Proteobacteria in the sediments spanned Gammaproteobacteria (17-25%), Deltaproteobacteria (12-20%), and Alphaproteobacteria (7-14%). Whereas, more operational taxonomic units (OTUs) belonging to Epsilonproteobacteria (19 ± 2.4%) were found in estuarine sediment unlike < 0.5% relative abundances obtained from oceanic sediments. Sulfurimonas apparently dominated the bacterial genera with up to 2.16 ± 0.19% abundance in oceanic sediments. Canonical correspondence analysis revealed that PHs shaped the structure of bacterial OTUs in oceanic sediments where petroleum loading/offloading occurs unlike in some kilometres a yonder where HMs correlated with the bacteria structure. The dominant bacteria might possibly pivotal to ecophysiologies of hydrocarbon contaminated marine environment, and would be pertinent to biotechnological applications for possible bioremediation campaign.

Production, functional stability, and effect of rhamnolipid biosurfactant from Klebsiella sp. on phenanthrene degradation in various medium systems

The present study investigated the stability and efficacy of a biosurfactant produced by Klebsiella sp. KOD36 under extreme conditions and its potential for enhancing the solubilization and degradation of phenanthrene in various environmental matrices. Klebsiella sp. KOD36 produced a mono-rhamnolipids biosurfactant with a low critical micelle concentration (CMC) value. The biosurfactant was stable under extreme conditions (60 °C, pH 10 and 10% salinity) and could lower surface tension by 30% and maintained an emulsification index of > 40%. The emulsion index was also higher (17-43%) in the presence of petroleum hydrocarbons compared to synthetic surfactant Triton X-100. Investigation on phenanthrene degradation in three different environmental matrices (aqueous, soil-slurry and soil) confirmed that the biosurfactant enhanced the solubilization and biodegradation of phenanthrene in all matrices. The high functional stability and performance of the biosurfactant under extreme conditions on phenanthrene degradation show the great potential of the biosurfactant for remediation applications under harsh environmental conditions.

Biosurfactant Production and Growth Kinetics Studies of the Waste Canola Oil-Degrading Bacterium Rhodococcus erythropolis AQ5-07 from Antarctica

With the progressive increase in human activities in the Antarctic region, the possibility of domestic oil spillage also increases. Developing means for the removal of oils, such as canola oil, from the environment and waste "grey" water using biological approaches is therefore desirable, since the thermal process of oil degradation is expensive and ineffective. Thus, in this study an indigenous cold-adapted Antarctic soil bacterium, Rhodococcus erythropolis strain AQ5-07, was screened for biosurfactant production ability using the multiple approaches of blood haemolysis, surface tension, emulsification index, oil spreading, drop collapse and "MATH" assay for cellular hydrophobicity. The growth kinetics of the bacterium containing different canola oil concentration was studied. The strain showed β-haemolysis on blood agar with a high emulsification index and low surface tension value of 91.5% and 25.14 mN/m, respectively. Of the models tested, the Haldane model provided the best description of the growth kinetics, although several models were similar in performance. Parameters obtained from the modelling were the maximum specific growth rate (qmax), concentration of substrate at the half maximum specific growth rate, Ks% (v/v) and the inhibition constant Ki% (v/v), with values of 0.142 h-1, 7.743% (v/v) and 0.399% (v/v), respectively. These biological coefficients are useful in predicting growth conditions for batch studies, and also relevant to "in field" bioremediation strategies where the concentration of oil might need to be diluted to non-toxic levels prior to remediation. Biosurfactants can also have application in enhanced oil recovery (EOR) under different environmental conditions.

Characterization of Pseudomonas sp. TMB2 produced rhamnolipids for ex-situ microbial enhanced oil recovery

The present study describes the ex-situ production of a biosurfactant by Pseudomonas sp. TMB2 for its potential application in enhancing oil recovery. The physicochemical parameters such as temperature and pH were optimized as 30 °C and 7.2, respectively, for their maximum laboratory scale production in mineral salt medium containing glucose and sodium nitrate as best carbon and nitrogen sources. The surface activity of the resulting culture broth was declined from 71.9 to 33.4 mN/m having the highest emulsification activity against kerosene oil. The extracted biosurfactant was characterized chemically as glycolipid by Fourier-transform infrared spectroscopy and 1H and 13C nuclear magnetic resonance spectroscopy analyses. The presence of mono-rhamnolipids (Rha-C8:2, Rha-C10, Rha-C10-C10, and Rha-C10-C12:1) and di-rhamnolipids (Rha-Rha-C12-C10, Rha-Rha-C10-C10, and Rha-Rha-C10-C12:1) congeners were determined by liquid chromatography-mass spectroscopy analysis. The thermostability and degradation pattern of the candidate biosurfactant were tested by thermogravimetry assay and differential scanning calorimetry studies for its suitability in ex-situ oil recovery technology. The rhamnolipid based slug, prepared in 4000 ppm brine solution reduced the interfacial tension between liquid paraffin oil and aqueous solution to 0.8 mN/m from 39.1 mN/m at critical micelle concentration of 120 mg/L. The flooding test was performed using conventional core plugs belonging to oil producing horizons of Upper Assam Basin and recovered 16.7% of original oil in place after secondary brine flooding with microscopic displacement efficiency of 27.11%.

Biosurfactant: A new frontier for greener technology and environmental sustainability

Petroleum hydrocarbons, oil, heavy metals pollution is becoming additional severe problem due to the growing call for crude oil and crude oil products related products in several fields of application. Such pollution have fascinated much considerations and attractions as it leads to ecological damages in both marines, aquatic and terrestrial ecosystems. Thus, different techniques including chemical surfactants and complex technologies have been proposed for their clean up from the environment, which in turn has detrimental effects on the environment. As of late, biosurfactant compounds have added much deliberation since they are considered as a reasonable option and eco-accommodating materials for remediation technology. The present society is confronting a few difficulties of usage, authorizing ecological protection and environmental change for the next generations. Biosurfactants hold the special property of minimizing and reducing the interfacial tension of liquids. Such features endure biosurfactants to afford a major part in emulsification, de-emulsification, biodegradability, foam formation, washing performance, surface activity, and detergent formulation, which have potential applications in the diverse industrial set-up. Conversations on cost-effective technologies, renewable materials, novel synthesis, downstream, upstream, emerging characterization techniques, molecular, and genetical engineering are substantial to produce biosurfactant of quality and quantity. Therefore, greater attention is being paid to biosurfactant production by identifying their environmental, and biotechnological applications. Be that as it may, the extravagant cost drew in with biosurfactants biotechnological synthesis and recovery can hamper their application in those areas. Notwithstanding these costs, biosurfactants can be used as these parts shows outstandingly high benefits that can at present beat the expenses incurred in the initial purification and downstream processes. Biosurfactant production by microorganisms is relatively considered one of the crucial know-how for improvement, growth, advancement, and environmental sustainability of the 21st century. There is a developing conversation around environmental safety and the significant role that biosurfactants will progressively play soon, for instance, the use of renewable by-products as substrates, potential reduction, re-use and recycling of waste and waste products. The review confers the usefulness of biosurfactants in the removal of environmental contaminants and, consequently, expanding environmental safety and drive towards greener technology.

Investigating the performance of an anaerobic baffled bioreactor for the biodegradation of alkaline-surfactant-polymer in oilfield water

The anaerobic baffled reactor (ABR) was used to treat alkaline-surfactant-polymer (ASP) flooding wastewater in the Daqing oilfield. With the ABR, hydraulic retention time (HRT)was reduced from 72  to 24 h, the bioreactor purification capability gradually improved. After the ABR running for 100 days, the removal rate of raw oil, suspended solid and surfactant reached 99.8%, 94.4% and 50%, respectively; alkali, polymer and viscosity were removed at a rate of about 16%, 7% and 20%, respectively. There were 39 kinds of organic materials detected by GCMS in the original water sample, while only 12 kinds of organics were left in the ABR outfall. The above results showed that the anaerobic, facultative anaerobic and aerobic compartment of ABR have strong capability of biodegrading petroleum pollution matter. Pyrosequencing analysis of the 16S rRNA indicated that Acinetobacter, Arcobacter, Pseudomonas and Paracoccus were the dominant bacteria genera present in the ABR reactor, among them Acinetobacter was the dominant species in the bacterial community.

Enhancement of Paenibacillus sp. D9 Lipopeptide Biosurfactant Production Through the Optimization of Medium Composition and Its Application for Biodegradation of Hydrophobic Pollutants

Interests in biosurfactant in industrial and environmental applications have increased considerably in recent years, owing to their potential benefits over synthetic counterparts. The present study aimed at analyzing the stability and oil removal efficiency of a new lipopeptide biosurfactant produced by Paenibacillus sp. D9 and its feasibility of its use in biotechnological applications. Paenibacillus sp. D9 was evaluated for optimal growth conditions and improved production yield of lipopeptide biosurfactant with variations in different substrate parameters such as carbon (C), nitrogen (N), C:N: ratio, metal supplements, pH, and temperature. Enhanced biosurfactant production was observed when using diesel fuel and ammonium sulfate as carbon and nitrogen source respectively. The maximum biosurfactant yield of 4.11 g/L by Paenibacillus sp. D9 occurred at a C/N ratio of 3:1, at pH 7.0, 30 °C, 4.0 mM MgSO₄, and 1.5% inoculum size. The D9 biosurfactant was found to retain surface-active properties under the extreme conditions such as high thermal, acidic, alkaline, and salt concentration. The ability to emulsify further emphasizes its potential usage in biotechnological application. Additionally, the lipopeptide biosurfactant exhibited good performance in the degradation of highly toxic substances when compared with chemical surfactant, which proposes its probable application in biodegradation, microbial-enhanced oil recovery or bioremediation. Furthermore, the biosurfactants were effective in a test to stimulate the solubilization of hydrophobic pollutants in both liquid environments removing 49.1 to 65.1% diesel fuel including hydrophobic pollutants. The study highlights the usefulness of optimization of culture parameters and their effects on biosurfactant production, high stability, improved desorption, and solubilization of hydrophobic pollutants.

Polycyclic Aromatic Hydrocarbons: A Critical Review of Environmental Occurrence and Bioremediation

The degree of polycyclic aromatic hydrocarbon contamination of environmental matrices has increased over the last several years due to increase in industrial activities. Interest has surrounded the occurrence and distribution of polycyclic aromatic hydrocarbons for many decades because they pose a serious threat to the health of humans and ecosystems. The importance of the need for sustainable abatement strategies to alleviate contamination therefore cannot be overemphasised, as daily human activities continue to create pollution from polycyclic aromatic hydrocarbons and impact the natural environment. Globally, attempts have been made to design treatment schemes for the remediation and restoration of contaminated sites. Several techniques and technologies have been proposed and tested over time, the majority of which have significant limitations. This has necessitated research into environmentally friendly and cost-effective clean-up techniques. Bioremediation is an appealing option that has been extensively researched and adopted as it has been proven to be relatively cost-effective, environmentally friendly and is publicly accepted. In this review, the physicochemical properties of some priority polycyclic aromatic hydrocarbons, as well as the pathways and mechanisms through which they enter the soil, river systems, drinking water, groundwater and food are succinctly examined. Their effects on human health, other living organisms, the aquatic ecosystem, as well as soil microbiota are also elucidated. The persistence and bioavailability of polycyclic aromatic hydrocarbons are discussed as well, as they are important factors that influence the rate, efficiency and overall success of remediation. Bioremediation (aerobic and anaerobic), use of biosurfactants and bioreactors, as well as the roles of biofilms in the biological treatment of polycyclic aromatic hydrocarbons are also explored.

Characterization of a novel bioemulsifier from Pseudomonas stutzeri

This study describes a novel and efficient alasan-like bioemulsifier produced by Pseudomonas stutzeri NJtech 11-1, which was isolated from the Shengli Oilfield. The strain was found to produce a new and interesting emulsion stabilizer. The crude bioemulsifier showed super stability with 50% salinity and broad pH 3-10. The emulsion index (EI₂₄) was increased to 100% after heating from 45 to 95 °C and the emulsion could be stable for at least 30 days. The yield of Ps-bioemulsifier (pure bioemulsifier) was 0.68 ± 0.05 mg mL^-1. The Ps-bioemulsifier was composed of carbohydrates (80 ± 2.6%) and proteins (9.5 ± 0.5%). A low concentration (0.2 mg mL^-1) of the Ps-bioemulsifier was obtained maximum emulsifying activity at pH 7.1 and its emulsifying activity strengthened by suitable salinity. Furthermore, Ps-bioemulsifier could also emulsify cyclohexane, hexadecane, kerosene, xylene hydrocarbons efficiently. Therefore, the Ps-bioemulsifier showed emulsifying characteristics which make it a good candidate for potential applications in bioremediation and microbial enhanced oil recovery.

Phenanthrene removal from liquid medium with emphasis on production of biosurfactant

In the current study, there are some considerable issues which focused on: (1) the production of biosurfactant, (2) its correlation with the initial bacterial inoculum in the liquid phase and (3) its effect on polycyclic hydrocarbon (PAH) bioremediation performance. Therefore, two strains Pseudomonas facilis and Pseudomonas spp. were able to form a large clear zone diameter on the oil surface. Phenanthrene (PHE) was also utilized as a sole substrate. Furthermore, biosurfactant production (BP) was detected by methylene blue analysis procedure and surface tension (ST) lowering. The capacity of these two strains to lower the aqueous ST was 29 and 30.7 from 72 mN m^-1 by 6 days for P. facilis and Pseudomonas spp., respectively. Higher initial bacterial inoculation led to an improvement in PHE removal (P < 0.0001). But there was no significant correlation between either PHE solubility or BP and the initial bacterial inoculation. The removal efficiency of 88.44% within 21 days confirms that the inoculation of P. facilis led to the considerable BP for removal of PAHs from contaminated water.

Bioremediation of petroleum contaminated soil to combat toxicity on Withania somnifera through seed priming with biosurfactant producing plant growth promoting rhizobacteria

Soil contaminated by Petroleum oil cannot be utilized for agricultural purposes due to hydrocarbon toxicity. Oil contaminated soil induces toxicity affecting germination, growth and productivity. Several technologies have been proposed for bioremediation of oil contaminated sites, but remediation through biosurfactant producing plant growth promontory rhizobacteria (PGPR) is considered to be most promising methods. In the present study the efficacy of seed priming on growth and pigment of Withania somnifera under petroleum toxicity is explored. Seeds of W. somnifera were primed with biosurfactant producing Pseudomonas sp. AJ15 with plant growth promoting traits having potentiality to utilized petroleum as carbon source. Results indicates that plant arose from priming seeds under various petroleum concentration expressed high values for all the parameters studied namely germination, shoot length, root length, fresh and dry weight and pigments (chlorophyll and carotenoid) as compared to non primed seed. Hence, the present study signifies that petroleum degrarding biosurfactant producing PGPR could be further used for management and detoxification of petroleum contaminated soils for growing economically important crops.

Remediation technologies for oil-contaminated sediments

Oil-contaminated sediments pose serious environmental hazards for both aquatic and terrestrial ecosystems. Innovative and environmentally compatible technologies are urgently required to remove oil-contaminated sediments. In this paper, various physical, chemical and biological technologies are investigated for the remediation of oil-contaminated sediments such as flotation and washing, coal agglomeration, thermal desorption, ultrasonic desorption, bioremediation, chemical oxidation and extraction using ionic liquids. The basic principles of these technologies as well as their advantages and disadvantages for practical application have been discussed. A combination of two or more technologies is expected to provide an innovative solution that is economical, eco-friendly and adaptable.

Biosurfactant production by Pseudomonas aeruginosa DSVP20 isolated from petroleum hydrocarbon-contaminated soil and its physicochemical characterization

Among 348 microbial strains isolated from petroleum hydrocarbon-contaminated soil, five were selected for their ability to produce biosurfactant based on battery of screening assay including hemolytic activity, surface tension reduction, drop collapse assay, emulsification activity, and cell surface hydrophobicity studies. Of these, bacterial isolate DSVP20 was identified as Pseudomonas aeruginosa (NCBI GenBank accession no. GQ865644) based on biochemical characterization and the 16S rDNA analysis, and it was found to be a potential candidate for biosurfactant production. Maximum biosurfactant production recorded by P. aeruginosa DSVP20 was 6.7 g/l after 72 h at 150 rpm and at a temperature of 30 °C. Chromatographic analysis and high-performance liquid chromatography-mass spectrometry (HPLC-MS) revealed that it was a glycolipid in nature which was further confirmed by nuclear magnetic resonance (NMR) spectroscopy. Bioremediation studies using purified biosurfactant showed that P. aeruginosa DSVP20 has the ability to degrade eicosane (97%), pristane (75%), and fluoranthene (47%) when studied at different time intervals for a total of 7 days. The results of this study showed that the P. aeruginosa DSVP20 and/or biosurfactant produced by this isolate have the potential role in bioremediation of petroleum hydrocarbon-contaminated soil.

Biodegradation of waste lubricants by a newly isolated Ochrobactrum sp. C1

A potential degrader of paraffinic and aromatic hydrocarbons was isolated from oil-contaminated soil from steel plant effluent area in Burnpur, India. The strain was investigated for degradation of waste lubricants (waste engine oil and waste transformer oil) that often contain EPA (Environmental Protection Agency, USA) classified priority pollutants and was identified as Ochrobactrum sp. C1 by 16S rRNA gene sequencing. The strain C1 was found to tolerate unusually high waste lubricant concentration along with emulsification capability of the culture broth, and its degradation efficiency was 48.5 ± 0.5 % for waste engine oil and 30.47 ± 0.25 % for waste transformer oil during 7 days incubation period. In order to get optimal degradation efficiency, a three level Box-Behnken design was employed to optimize the physical parameters namely pH, temperature and waste oil concentration. The results indicate that at temperature 36.4 °C, pH 7.3 and with 4.6 % (v/v) oil concentration, the percentage degradation of waste engine oil will be 57 % within 7 days. At this optimized condition, the experimental values (56.7 ± 0.25 %) are in a good agreement with the predicted values with a calculated R 2 to be 0.998 and significant correlation between biodegradation and emulsification activity (E 24 = 69.42 ± 0.32 %) of the culture broth toward engine oil was found with a correlation coefficient of 0.972. This is the first study showing that an Ochrobactrum sp. strain is capable of degrading waste lubricants, which might contribute to the bioremediation of waste lubricating oil-contaminated soil.

Pseudosolubilized n-alkanes analysis and optimization of biosurfactants production by Pseudomonas sp. DG17

The pseudosolubilized medium-chain-length n-alkanes during biodegradation process, and optimization of medium composition and culture conditions for rhamnolipid production by Pseudomonas sp. DG17 using Plackett-Burman design and Box-Behnken design, were examined in this study. The results showed that pseudosolubilized concentration of C14 to C20 n-alkanes was higher than that of C24 to C26. After incubation for 120 h, pseudosolubilized C16H34 increased to 2.63 ± 0.21 mg. Meanwhile, biodegradation rates of n-alkanes decreased along with the increase of carbon chain length. Carbon-14 assay suggested that nonlabeled C14H30, C16H34, and C20H42 inhibited the biodegradation of (14)C n-octadecane, and Pseudomonas sp. DG17 utilized different alkanes simultaneously. Three significant variables (substrate concentration, salinity, and C/N) that could influence rhamnolipid production were screened by Plackett-Burman design. Results of Box-Behnken design suggested that rhamnolipid concentration could be achieved at 91.24 mg L(-1) (observed value) or 87.92 mg L(-1) (predicted value) with the optimal levels of concentration, salinity, and C/N of 400 mg L(-1), 1.5 %, and 45, respectively.

Assessing Bacillus subtilis biosurfactant effects on the biodegradation of petroleum products

Microbial pollutant removal capabilities can be determined and exploited to accomplish bioremediation of hydrocarbon-polluted environments. Thus, increasing knowledge on environmental behavior of different petroleum products can lead to better bioremediation strategies. Biodegradation can be enhanced by adding biosurfactants to hydrocarbon-degrading microorganism consortia. This work aimed to improve petroleum products biodegradation by using a biosurfactant produced by Bacillus subtilis. The produced biosurfactant was added to biodegradation assays containing crude oil, diesel, and kerosene. Biodegradation was monitored by a respirometric technique capable of evaluating CO₂ production in an aerobic simulated wastewater environment. The biosurfactant yielded optimal surface tension reduction (30.9 mN m(-1)) and emulsification results (46.90% with kerosene). Biodegradation successfully occurred and different profiles were observed for each substance. Precise mathematical modeling of biosurfactant effects on petroleum degradation profile was designed, hence allowing long-term kinetics prediction. Assays containing biosurfactant yielded a higher overall CO₂ output. Higher emulsification and an enhanced CO2 production dataset on assays containing biosurfactants was observed, especially in crude oil and kerosene.

Characterization of hydrocarbon-degrading and biosurfactant-producing Pseudomonas sp. P-1 strain as a potential tool for bioremediation of petroleum-contaminated soil

The Pseudomonas sp. P-1 strain, isolated from heavily petroleum hydrocarbon-contaminated soil, was investigated for its capability to degrade hydrocarbons and produce a biosurfactant. The strain degraded crude oil, fractions A5 and P3 of crude oil, and hexadecane (27, 39, 27 and 13% of hydrocarbons added to culture medium were degraded, respectively) but had no ability to degrade phenanthrene. Additionally, the presence of gene-encoding enzymes responsible for the degradation of alkanes and naphthalene in the genome of the P-1 strain was reported. Positive results of blood agar and methylene blue agar tests, as well as the presence of gene rhl, involved in the biosynthesis of rhamnolipid, confirmed the ability of P-1 for synthesis of glycolipid biosurfactant. 1H and 13C nuclear magnetic resonance, Fourier transform infrared spectrum and mass spectrum analyses indicated that the extracted biosurfactant was affiliated with rhamnolipid. The results of this study indicate that the P-1 and/or biosurfactant produced by this strain have the potential to be used in bioremediation of hydrocarbon-contaminated soils.

Biodegradation of petroleum hydrocarbons in the presence of nickel and cobalt

Bioremediation of environments co-contaminated with hydrocarbons and heavy metals often pose a challenge as heavy metals exert toxicity to existing communities of hydrocarbon degraders. Multi-resistant bacterial strains were studied for ability to degrade hydrocarbons in chemically defined media amended with 5.0 mM Ni(2+), and Co(2+). The bacteria, Pseudomonas aeruginosa CA207Ni, Burkholderia cepacia AL96Co, and Corynebacterium kutscheri FL108Hg, utilized crude oil and anthracene without lag phase at specific growth rate spanning 0.3848-0.8259 per day. The bacterial populations grew in hydrocarbon media amended with nickel (Ni) and cobalt (Co) at 0.8393-1.801 days generation time (period of exponential growth, t = 15 days). The bacteria degraded 96.24-98.97, and 92.94-96.24% of crude oil, and anthracene, respectively, within 30 days without any impedance due to metal toxicity (at 5.0 mM). Rather, there was reduction of Ni and Co concentrations in the axenic culture 30 days post-inoculation to 0.08-0.12 and 0.11-0.15 mM, respectively. The metabolic functions of the bacteria are active in the presence of toxic metals (Ni and Co) while utilizing petroleum hydrocarbons for increase in biomass. These findings are useful to other baseline studies on decommissioning of sites co-contaminated with hydrocarbons and toxic metals.

Role of plasmid in diesel oil degradation by yeast species isolated from petroleum hydrocarbon-contaminated soil

Five yeast species, namely Candida tropicalis, Cryptococcus laurentii, Trichosporon asahii, Rhodotorula mucilaginosa and Candida rugosa isolated from hydrocarbon-contaminated soil were found to be potent degraders of diesel oil. These microorganisms showed the presence of enzymes cytochrome P450, NADPH cytochrome c reductase, aminopyrine N demethylase, alcohol dehydrogenase, aldehyde dehydrogenase, naphthalene dioxygenase, catalase and glutathione S transferase when the cells were incubated for 48 h in Bushnell Haas medium supplemented with 2% diesel oil as the sole source of carbon. The cytochrome P450 monooxygenase enzyme system was found to play an important role in diesel oil degradation. A plasmid approximately 12kb in size was found to be harboured by all the yeast species. The role of the plasmid on diesel oil degradation was assessed by biomass inhibition studies, which confirmed that the metabolic machinery of yeast species for diesel oil degradation was plasmid coded. This is the first report establishing the involvement of a plasmid in diesel oil degradation by yeast species.

Ex situ treatment of hydrocarbon-contaminated soil using biosurfactants from Lactobacillus pentosus

The utilization of biosurfactants for the bioremediation of contaminated soil is not yet well established, because of the high production cost of biosurfactants. Consequently, it is interesting to look for new biosurfactants that can be produced at a large scale, and it can be employed for the bioremediation of contaminated sites. In this work, biosurfactants from Lactobacillus pentosus growing in hemicellulosic sugars solutions, with a similar composition of sugars found in trimming vine shoot hydrolysates, were employed in the bioremediation of soil contaminated with octane. It was observed that the presence of biosurfactant from L. pentosus accelerated the biodegradation of octane in soil. After 15 days of treatment, biosurfactants from L. pentosus reduced the concentration of octane in the soil to 58.6 and 62.8%, for soil charged with 700 and 70,000 mg/kg of hydrocarbon, respectively, whereas after 30 days of treatment, 76% of octane in soil was biodegraded in both cases. In the absence of biosurfactant and after 15 days of incubation, only 1.2 and 24% of octane was biodegraded in soil charged with 700 and 70,000 mg/kg of octane, respectively. Thus, the use of biosurfactants from L. pentosus, as part of a well-designed bioremediation process, can provide mechanisms to mobilize the target contaminants from the soil surface to make them more available to the microbial population.

Environmental applications of biosurfactants: recent advances

Increasing public awareness of environmental pollution influences the search and development of technologies that help in clean up of organic and inorganic contaminants such as hydrocarbons and metals. An alternative and eco-friendly method of remediation technology of environments contaminated with these pollutants is the use of biosurfactants and biosurfactant-producing microorganisms. The diversity of biosurfactants makes them an attractive group of compounds for potential use in a wide variety of industrial and biotechnological applications. The purpose of this review is to provide a comprehensive overview of advances in the applications of biosurfactants and biosurfactant-producing microorganisms in hydrocarbon and metal remediation technologies.

Microbial degradation of petroleum hydrocarbon contaminants: an overview

One of the major environmental problems today is hydrocarbon contamination resulting from the activities related to the petrochemical industry. Accidental releases of petroleum products are of particular concern in the environment. Hydrocarbon components have been known to belong to the family of carcinogens and neurotoxic organic pollutants. Currently accepted disposal methods of incineration or burial insecure landfills can become prohibitively expensive when amounts of contaminants are large. Mechanical and chemical methods generally used to remove hydrocarbons from contaminated sites have limited effectiveness and can be expensive. Bioremediation is the promising technology for the treatment of these contaminated sites since it is cost-effective and will lead to complete mineralization. Bioremediation functions basically on biodegradation, which may refer to complete mineralization of organic contaminants into carbon dioxide, water, inorganic compounds, and cell protein or transformation of complex organic contaminants to other simpler organic compounds by biological agents like microorganisms. Many indigenous microorganisms in water and soil are capable of degrading hydrocarbon contaminants. This paper presents an updated overview of petroleum hydrocarbon degradation by microorganisms under different ecosystems.