History of Arthrobacter aurescens TC1

Direct isolation of A. aurescens TC1 growing on cell plate.

In the spring of 1997, a 250 gallon tank of the herbicide atrazine was spilled onto rural land. Contaminating 35 cubic yards, the soil was collected and analyzed. The average concentration of atrazine levels was found to be 11,500 ppm, far above the normal usage levels of 2 ppm.

Read more about the site of Arthrobacter aurescens strain TC1 isolation.

While atrazine in this spill site soil was being biodegraded by microorganisms indigenous to the soil, it was also found that a specialized bacteria Arthrobacter aurescens TC1 degraded the toxic herbicide.

This strain of A. aurescens was studied further, concentrating on its ability to utilize compounds similar to atrazine as a nutrient source. The graphs below compare A. aurescens ability to utilize the various s-triazines as a soul source of nitrogen at a concentration of 200 mg/L as opposed to pure atrazine at varying levels of concentration. The level of absorbance is directly related to the ability of the bacteria to thrive using the various nutrient sources.

A,B,C - The s-triazine substrate range the organism is active against:

The figure below shows the influence of different concentractions of atrazine on growth of A. aurescens TC1. Strain TC1 was grown in minimal medium using atrazine as a sole source of carbon, nitrogen, and energy. Culture grown with 500 mg of atrazine per liter (white boxes) and culture initially grown on 500 mg of atrazine per liter (black boxes) at the time indicated by the arrow.

The following figure shows the utilization of N-alkyl amines as a source of C and N by A. aurescens TC1. Cells were grown in minimal medium containing 7.5 mM N-isopropylamine plus 15 mM ammonium nitrate (A), 7.5 mM N-isopropylamine (B), 7.5 mM ethylamine plus 15 mM ammonium nitrate (C), and 7.5 mM ethylamine (D).