UTILIZATION OF N-ALKANES AND PETROLEUM DERIVATES BY BACTERIA PRESENT IN A CONSORTIUM.

PAGGI RA; RUIZ DM

Rosario (Santa Fe)

Congreso; VI Congreso XXIV Reunión Anual - Sociedad de Biología de Rosario.; 2004

Sociedad de Biología de Rosario

Microbial bioremediation has been studied in the last decades. Isolated microorganisms can use limited number of compounds, but in the environment they form a mixed population that increases the biodegradation rate. Little is known about the interactions among them. A microbial consortium able to grow with hexadecane (Hxd) as carbon source has been isolated from a gas oil-contaminated soil. The microorganisms were identified as Corynebacterium sp and Agrobacterium sp. The aim of this work is to study the utilization of n-alkanes and petroleum mixtures as carbon source by these bacteria. The utilization of the different compounds was analyzed by increases in optical density after 14 days of incubation at 25°C. The following n-alkanes were added at 0.2 % to a mineral salt medium: hexane, heptane, octane, iso-octane, undecane, dodecane, pentadecane, Hxd; gas-oil and 3 different petroleum cuts were used as complex mixtures. Then, the optimum concentration for growth was determined by supplementing the medium with 0.025 to 10 % of each. The results show that only Corynebacterium is able to use n-alkanes longer than 8 C to grow. Although both bacteria were able to grow in gas-oil, only Corynebacterium grew in cut n° 2, which is rich in n-decane. Both types of microorganisms were found after co-cultures incubation adding undecane, dodecane, pentadecane and Hxd. These indicate that both bacteria use different compounds for growth and it could produce an increase in the degradation rate of gas-oil components. Moreover, the existence of a metabolic interrelation between them due to the fact that Agrobacterium is able to growth at the expense of a subproduct generated by Corynebacterium sp.