Poster Presentation 1B-39

Intracellular Fate of Hydrocarbons:

Possibility of Existence of Specific Compartments for its Biodegradation

Roberto Zazueta-Sandoval* and Hortensia Silva Jiménez

IIBE. Facultad de Química

Universidad de Guanajuato

Noria Alta s/n CP 36050. Guanajuato, Gto

Phone: (473)732 0006 ext. 8148

Fax: ext. 8153

E-mail: zazueta@ quijote.ugto.mx

As a result of improper disposal processes or spills of petroleum or petroleum-derived products, there are many contamination problems in soils produced by hydrocarbon compounds. In this sense, many microorganisms have the capability to metabolize those compounds which represents a biotechnological importance in the field of bioremediation. There is a continuous increase in the number and amount of toxic compounds generated by our own society. It is becoming increasingly important to develop new enzymatic or microbiological techniques to detoxify and degrade most of these waste products. We are interested in the study of oxidoreductases involved in the first and second steps of hydrocarbon biodegradation in filamentous fungi.

In aliphatic hydrocarbon oxidation the first enzymatic step is catalyzed by a mono-oxygenase to incorporate one atom of oxygen into the organic compounds. So, through the action of oxygenase, the hydrophobic organic compounds become more water soluble and can be metabolized or broken down by a large number of other microorganisms. The second step in this pathway is catalyzed by the activity of an alcohol oxidase to make the fat-alcohol derivate followed by the fat-aldehyde dehydrogenase. This has been an important enzyme because it has many biotechnological applications, primarily in alcohol detection; in our own study, it is central for future bioremediation processes.

In the present work, we describe some interesting features about the intracellular localization of these enzymes. In literature references it has been established that the first reaction is performed in microsomes and the second in peroxisomes. In our own results there are some differences because both activities are founded in intercellular vesicles with different density than peroxisomas after isopicnic gradients of 10-60% sucrose, when the microorganism was grown in minimal salts medium with 0.1 % peptone added and decane as the sole carbon source. We experimented using different carbon sources, including glucose, decane and hexadecane as sole carbon sources. The expression of AO activity in cell free extracts was detected only when hydrocarbon was present in the culture media and located in the density of the mentioned vesicles. In cases when glucose was present, no AO activity could be detected.