Oil spills: impacts and perspectives of treatment technologies with focus on the use of green surfactants.

Oil spills into the oceans cause irreparable damage to marine life and harms the coastal population of the affected areas. The main measures to be taken in response to an oil spill are to reduce the impact on marine life, prevent oil from reaching the shore through its recovery, and accelerate the degradation of unrecovered oil. Any environmental damage can be reduced if the spilled oil is removed from the water quickly and efficiently. Therefore, it is essential to know the treatment strategies for spilled oils. Several technologies are currently available, including booms, skimmers, in situ burning, use of adsorbents, dispersants/surfactants, and bioremediation. The selection of the type of treatment will depend not only on the effectiveness of the technique, but mainly on the type of oil, amount spilled, location, weather, and sea conditions. In this review, the characteristics of oil spills, their origin, destination, and impacts caused, including major accidents around the world, are initially addressed. Then, the main physical, chemical, and biological treatment technologies are presented, describing their advances, advantages, and drawbacks, with a focus on the use of green surfactants. These agents will be described in detail, showing the evolution of research, recent studies, patents, and commercialized products. Finally, the challenges that remain due to spills, the necessary actions, and the prospects for the development of existing treatment technologies are discussed, which must be linked to the use of combined techniques.

Production of green surfactants: market prospects

Science has greatly contributed to the advancement of technology and to the innovation of production processes and their applications. Cleaning products have become indispensable in today's world, as personal and environmental hygiene is important to all societies worldwide. Such products are used in the home, in most work environments and in the industrial sectors. Most of the detergents on the market are synthesised from petrochemical products. However, the interest in reducing the use of products harmful to human health and the environment has led to the search for detergents formulated with natural, biodegradable surfactant components of biological (plant or microbiological) origin or chemically synthesised from natural raw materials usually referred to as green surfactants. This review addresses the different types, properties, and uses of surfactants, with a focus on green surfactants, and describes the current scenario as well as the projections for the future market economy related to the production of the different types of green surfactants marketed in the world.

Production of cupcake-like dessert containing microbial biosurfactant as an emulsifier.

This work describes the application of the biosurfactant from Candida bombicola URM 3718 as a meal additive like cupcake. The biosurfactant was produced in a culture medium containing 5% sugar cane molasses, 5% residual soybean oil and 3% corn steep liquor. The surface and interfacial tension of the biosurfactant were 30.790 ± 0.04 mN/m and 0.730 ± 0.05 mN/m, respectively. The yield in isolated biosurfactant was 25 ± 1.02 g/L and the CMC was 0.5 g/L. The emulsions of the isolated biosurfactant with vegetable oils showed satisfactory results. The microphotographs of the emulsions showed that increasing the concentration of biosurfactant decreased the oil droplets, increasing the stability of the emulsions. The biosurfactant was incorporated into the cupcake dessert formulation, replacing 50%, 75% and 100% of the vegetable fat in the standard formulation. Thermal analysis showed that the biosurfactant is stable for cooking cupcakes (180 °C). The biosurfactant proved to be promising for application in foods low in antioxidants and did not show cytotoxic potential in the tested cell lines. Cupcakes with biosurfactant incorporated in their dough did not show significant differences in physical and physical-chemical properties after baking when compared to the standard formulation. In this way, the biosurfactant has potential for application in the food industry as an emulsifier for flour dessert.

Treatment of oily effluent using a low-cost biosurfactant in a flotation system.

Fuel and lubricating oil leaks produce an oily wastewater that creates an environmental problem for industries. Dissolved air flotation (DAF) has been successfully employed for the separation of oily contaminants. Collectors constitute an auxiliary tool in the DAF process that enhances the separation efficiency by facilitating the adhesion of the contaminant particles. The use of biosurfactants as collectors is a promising technology in flotation processes, as these biomolecules are biodegradable and non-toxic. In the present study, a biosurfactant was produced from the bacteria Pseudomonas aeruginosa UCP 0992 cultivated in 0.5% corn steep liquor and 4.0% vegetable oil residue in a bioreactor at 225 rpm for 120 h, resulting in a surface tension of 26.5 mN/m and a yield of 26 g/L. The biosurfactant demonstrated stability when exposed to different temperatures, heating times, pH values and salt and was characterised as a glycolipid with a critical micelle concentration of 600 mg/L. A central composite rotatable design was used to evaluate the effect of the crude biosurfactant added to a laboratory DAF prototype on the removal efficiency of motor oil. The isolated and formulated forms of the biosurfactant were also tested in the prototype after the optimisation of the operational conditions. The results demonstrated that all forms of the biosurfactant increased the oil separation efficiency of the DAF process by 65 to 95%. In conclusion, the use of biosurfactants is a promising alternative as an auxiliary tool in flotation processes for the treatment of oily waters generated by industrial activities.

Production and formulation of a new low-cost biosurfactant to remediate oil-contaminated seawater.

The aim of the present study was to produce biosurfactants using three bacterial strains (Pseudomonas cepacia CCT6659, Bacillus methylotrophicus UCP 1616 and Bacillus cereus UCP 1615) cultivated in mineral medium containing different carbon (glucose, sucrose, molasses and waste frying oil) and nitrogen [NH4NO3, (NH4)2SO4, peptone, yeast extract and corn steep liquor] sources. B. cereus stood out as the best biosurfactant producer when inoculated with a 1.5% cell suspension and cultivated at 28 °C and 200 rpm in 2.0% molasses and 1.0% corn steep liquor for 48 h. Under these conditions, medium surface tension was reduced to 26.2 ± 0.2 mN/m, and biosurfactant concentration achieved 2.05 ± 0.32 g/L. The biosurfactant showed a critical micelle concentration of 0.90 ± 0.05 g/L, proved to be highly stable in wide ranges of pH, salt concentration and heating temperature, and exerted low toxicity to larvae of Artemia salina as a marine environmental bioindicator. Structural characterisation of biosurfactant suggested a lipopeptide composition. The biotensioactive agent was shown to effectively remove motor oil adsorbed to marine rock (91.0 ± 0.4%) and to disperse it in seawater (70.0 ± 0.4%). The biosurfactant formulated with 0.2% potassium sorbate demonstrated considerable potential for application in the petroleum industry, where it could be successfully used as a commercial product to mobilize oil in marine environments.

P53 mutation and response to hepatic arterial floxuridine in patients with colorectal liver metastases.

PURPOSE: To establish the relationship between the number and site of p53 genomic mutations in metastatic colorectal cancer, and the response to hepatic arterial floxuridine. METHODS: Liver metastasis biopsies were collected, at the time of laparotomy for hepatic arterial cannulation. in 28 patients with metachronous colorectal liver metastases. p53 Gene mutations were assessed using reverse transcription, nested polymerase chain reaction, single strand conformational polymorphism and gene sequencing. Chemotherapy response was determined from computerised liver tomograms after 4 months of treatment. RESULTS: Liver metastasis p53 mutation was identified in 21 (75%), and p53 "hot spot" mutation in 11 (39%) patients. There was a significantly lower prevalence (Fisher's, P=0.001) of patients with p53 "hot spot"-mutated liver metastases in stable disease and partial response (5/22) than in progressive (6/6) disease groups. Significantly fewer (Mann-Whitney U, P=0.002) p53 "hot spot" mutations/biopsy were observed in liver metastases from stable disease and partial response (median 0, iqr. 0-0) than in progressive (median 1, iqr 1-2) disease patients. p53 "Hot spot"-mutated liver metastases were associated with significantly shorter survival times (logrank P=0.05) after hepatic arterial floxuridine. Significant response or survival-time differences by total or L2/L3 zinc-binding site p53 mutations were not detected. CONCLUSIONS: The results support a role for p53 "hot spot" mutations in colorectal liver metastasis resistance to fluorinated pyrimidines, and suggest that the presence of such mutations may be a contra-indication to treatment of colorectal liver metastases with hepatic arterial floxuridine.

P53 mutations in primary and metastatic tumors and circulating tumor cells from colorectal carcinoma patients.

Circulating tumor cells could provide a relatively noninvasive and repeatable source of information about tumor cell genotype that might influence treatment and estimation of prognosis. We developed a technique for identifying p53 mutations in tumor cells isolated from the peripheral venous blood of colorectal cancer patients and compared the prevalence and position of these mutations with multiple solid tumor samples from the same patient. We used immunomagnetic beads to isolate tumor cells, reverse transcriptase-nested polymerase chain amplification of the coding region between exons 4 and 9 within the p53 gene, and automated gene sequencing. Nineteen p53 mutations were detected in solid tumor samples from 19 of 41 colorectal carcinoma patients. An identical p53 mutation was invariably present in all samples from primary and metastatic colorectal tumor biopsies within the same patient. p53 mutations were detected in peripheral blood from 8 of these 19 patients with p53-mutated solid tumors. Where identified, the pattern of mutation in peripheral blood samples was invariably the same as in matching solid tumor samples. A single colorectal carcinoma biopsy provided reliable p53 gene mutational information in colorectal carcinoma. Detection of this p53 mutation in tumor cells from peripheral blood was achieved with an approach based on cell selection for epithelial characteristics, reverse transcription-PCR, and gene sequencing.

Analysis of the proposed Fe-SX binding region of Photosystem 1 by site directed mutation of PsaA in Chlamydomonas reinhardtii.

The psaA and psaB genes of the chloroplast genome in oxygenic photosynthetic organisms code for the major peptides of the Photosystem 1 reaction center. A heterodimer of the two polypeptides PsaA and PsaB is thought to bind the reaction center chlorophyll, P700, and the early electron acceptors A0, A1 and Fe-SX. Fe-SX is a 4Fe4S center requiring 4 cysteine residues as ligands from the protein. As PsaA and PsaB have only three and two conserved cysteine residues respectively, it has been proposed by several groups that Fe-SX is an unusual inter-peptide center liganded by two cysteines from each peptide. This hypothesis has been tested by site directed mutagenesis of PsaA residue C575 and the adjacent D576. The C575D mutant does not assemble Photosystem 1. The C575H mutant contains a photoxidisable chlorophyll with EPR properties of P700, but no other Photosystem 1 function has been detected. The D576L mutant assembles a modified Photosystem 1 in which the EPR properties of the Fe-SA/B centers are altered. The results confirm the importance of the conserved cysteine motif region in Photosystem 1 structure.