Richard Bartha

Hydrocarbon Biodegradation and Oil Spill Bioremediation

Much of the early work on the microbial utilization of petroleum hydrocarbons, conducted in the 1950s and 1960s, was done with the goal of using hydrocarbons as substrates for producing microbial biomass (Shennan, 1984; Champagnat, 1964; Champagnat and Llewelyn, 1962; Cooney et al., 1980; Ballerini, 1978). Petroleum was viewed as an inexpensive carbon source and single cell protein (microbial biomass) was considered as a possible solution to the perceived impending world food shortage for the predicted global population explosion. Applied studies focused on optimizing microbial growth on low- to middle-molecular-weight hydrocarbons. These studies developed fermentor designs for large-scale single cell protein production with agitation and aeration systems that permitted high rates of microbial growth on soluble and highly emulsified hydrocarbon substrates. High-speed impellers (>800 rpm) were used to mix the hydrocarbon substrates and high rates of forced aeration with baffles within the fermentors were used to supply the molecular oxygen necessary for the microbial utilization of hydrocarbons (Hatch, 1975; Prokop and Sobotka, 1975). Optimized microbial growth in these fermentors consumes as much as 100,000 g hydrocarbon/m3 per day (Kanazawa, 1975).

Features of a Flask and Method for Measuring the Persistence and Biological Effects of Pesticides in Soil

Features of a Flask and Method for Measuring the Persistence and Biological Effects of Pesticides in Soil RICHARD BARTHA;DAVID PRAMER; Soil Science

Biotechnology of Petroleum Pollutant Biodegradation

Procedures designed to meet the physiological needs of petroleum hydrocarbon (PHC) degrading microorganisms are useful in mitigating environmental damage caused by marine and terrestrial PHC spills. By similar approaches, soil can be utilized as a cost-effective biological incinerator for hazardous PHC wastes. Physiological ecology needs to complement genetic engineering efforts for an effective attack on environmental pollution problems.

The Microbiology of Aquatic Oil Spills

Publisher Summary This chapter discusses the microbiology of aquatic oil spills. Immediately upon spilling, oil begins to undergo a series of physical and chemical changes. The processes causing these changes include spreading, emulsification, dissolution, evaporation, sedimentation, and adsorption. Collectively, the oil is weathered by these processes. The weathering of oil depends on the amount and type of oil spilled, and on environmental conditions. Petroleum hydrocarbons have only a very limited solubility in water. Therefore, most oil spillages initially form a surface slick. The surface slick can be moved by wind, wave, and current action. A surface oil slick immediately begins to spread, initially owing to gravitational forces, resulting in a thinner layer of oil covering a larger area. The viscosity of the spilled oil will, to some extent, influence the rate of spreading and, as viscosity is temperature dependent, water temperature will also influence the area covered by a surface slick. The chapter illustrates the effects of petroleum hydrocarbons on microorganisms, microbial emulsification and degradation of petroleum, and the microorganisms and oil pollution abatement.

Structure-biodegradability relationships of polycyclic aromatic hydrocarbons in soil

In a previous study on oily sludge disposal by land treatment, PAH as a class were found to be biodegraded more rapidly than the total solvent-extractable hydrocarbons of the sludge. This somewhat surprising result was apparently due to a predominance of low molecular weight PAH (less than or equal to 3 rings) in the sludge sample. The higher molecular weight PAH (greater than or equal to 4 rings) exhibited persistence that seemed to increase with the number of rings and the degree of ring condensation. In order to verify and extend these observations, the authors have undertaken here a systematic study on the structure-biodegradability relationship (SBR) of PAH in soil. Since it was expected that the majority of the PAH would be degraded cometabolically rather than in the substrate utilization mode, 1-phenyldecane was added as primary substrate in combination with all the PAH tested. In preliminary tests, 1-phenyldecane proved to be more effective in stimulating the biodegradation of 1,2-benzpyrene (benzo(a)pyrene) than either n-hexadecane, naphthoic acid or sewage sludge. The presence of an additional hydrocarbon substrate made this SBR study also more relevant to our previous work on the fate of PAH during the disposal of oily sludges by land treatment.

Rapid Mineralization of Benzo[a]pyrene by a Microbial Consortium Growing on Diesel Fuel

ABSTRACT A microbial consortium which rapidly mineralized the environmentally persistent pollutant benzo[a]pyrene was recovered from soil. The consortium cometabolically converted [7-14C]benzo[a]pyrene to14CO2 when it was grown on diesel fuel, and the extent of benzo[a]pyrene mineralization was dependent on both diesel fuel and benzo[a]pyrene concentrations. Addition of diesel fuel at concentrations ranging from 0.007 to 0.2% (wt/vol) stimulated the mineralization of 10 mg of benzo[a]pyrene per liter 33 to 65% during a 2-week incubation period. When the benzo[a]pyrene concentration was 10 to 100 mg liter−1 and the diesel fuel concentration was 0.1% (wt/vol), an inoculum containing 1 mg of cell protein per liter (small inoculum) resulted in mineralization of up to 17.2 mg of benzo[a]pyrene per liter in 16 days. This corresponded to 35% of the added radiolabel when the concentration of benzo[a]pyrene was 50 mg liter−1. A radiocarbon mass balance analysis recovered 25% of the added benzo[a]pyrene solubilized in the culture suspension prior to mineralization. Populations growing on diesel fuel most likely promoted emulsification of benzo[a]pyrene through the production of surface-active compounds. The consortium was also analyzed by PCR-denaturing gradient gel electrophoresis of 16S rRNA gene fragments, and 12 dominant bands, representing different sequence types, were detected during a 19-day incubation period. The onset of benzo[a]pyrene mineralization was compared to changes in the consortium community structure and was found to correlate with the emergence of at least four sequence types. DNA from 10 sequence types were successfully purified and sequenced, and that data revealed that eight of the consortium members were related to the classProteobacteria but that the consortium also included members which were related to the genera Mycobacterium andSphingobacterium.

Effects of bioremediation on residues, activity and toxicity in soil contaminated by fuel spills

Triplicate outdoor lysimeters were contaminated by 2.3 ml cm−2 spills of jet fuel, heating oil and diesel oil, respectively. One of each set of triplicates was left untreated, one was tilled only, and one received complete bioremediation treatment consisting of liming, fertilization and weekly tilling. For 20 weeks during summer, hydrocarbon residues were monitored by quantitative gas chromatography. Microbial activity was measured by fluorescein diacetate hydrolysis. Toxicity was assessed by Microtox measurements, seed germination and plant growth bioassays. Persistence and toxicity of the fuels increased in the order of jet fuel < heating oil < diesel oil. In each case, bioremediation treatment strongly decreased fuel persistence and toxicity and increased microbial activity as compared to contaminated but untreated soil. Tilling alone had a favorable but more limited effect. Good correlations were found between residue decline, microbial activity and toxicity reduction. Persistence and toxicity also correlated with the hydrocarbon composition of these three fuels. Our findings indicate that bioremediation treatment can restore fuel spill contaminated soils in 4–6 weeks to a degree that they can support plant cover. Recovery of the soil is complete in 20 weeks.

Stimulated biodegradation of oil slicks using oleophilic fertilizers.

Biodegradation of polluting oil at sea is seriously limited by the scarcity of nitrogen and phosphorus. Since water soluble sources of these elements could be ineffective in the ocean, oleophilic compounds were screened to serve as fertilizers for oil slicks. A combination of paraffinized urea and octylphosphate was found to promote oil biodegradation both in laboratory experiments and in field trials to an extent that the practical application of this principle to oil cleanup appears feasible. The tested oleophilic fertilizer supplies nutrients to hydrocarbon-degrading microorganisms selectively, and in contrast to nitrate and phosphate salts it does not trigger algal blooms.

INTERACTION OF PESTICIDE-DERIVED CHLOROANILINE RESIDUES WITH SOIL ORGANIC MATTER1

Herbicide-derived chloroaniline residues are immobilized by physical absorption to both the organic and the inorganic fraction of the soil and, in addition, by chemical binding to the soil organic matter. In contrast to the polymerization reactions, the binding of the chloroanilines is strictly a physicochemical process; microbial activity is involved only in the liberation of the chloroanilines from the parent herbicides. The chemical attachment of chloroanilines to humic substances occurs by at least two mechanisms, in a hydrolyzable (probably anil and anilinoquinone) and in a nonhydrolyzable (probably heterocyclic rings and ether bonds) manner. In the test soil (Nixon sandy loam) these two types of bonds immobilized roughly equal amounts of chloroanilines. Free radicals have little or no role in these reactions. The binding of chloroanilines to the soil organic matter greatly increases the persistence of these herbicide-derived residues in the environment.

Pesticide transformations: production of chloroazobenzenes from chloroanilines.

Aniline and 11 different chloroanilines were added to soil. No azo compound was formed from aniline, but all monochloro-and some dichloroanilines were transformed to their corresponding dichloro-and tetrachloroazobenzenes. Other dichloroanilines and the trichloroanilines were stable in soil. Peroxidase catalyzed the formation of azo compounds by some chloroanilines. Correspondence in the range of substrates used and products formed in the two systems suggests a peroxidatic mechanism for the synthesis of azo compounds residues in soil.