Strain of oil-eating bacteria isolated

By Wu Chong (China Daily)
Updated: 2007-03-20 11:28

Chinese scientists have cracked biological codes of a heat-tolerant bacterial strain that feeds on crude oil which holds the promise of applications such as the clean-up of oil contamination.

Geobacillus thermodenirificans NG80-2, the bacterial strain, was isolated from an oil well in Dagang Oil Field in North China's Tianjin, and has been shown to grow at temperatures of 45-73 C with crude oil as the sole energy source.

Researchers at Nankai University in Tianjin determined the genetic sequence of the bacterial strain after almost three years of experiments, and discovered its metabolic pathway.

"We identified the key enzyme that enables the bacterium to degrade long-chain alkanes, a chemical component of oil, to smaller molecules," said Wang Lei, a lead scientist of the research team at Nankai University.

"We also discovered a simple way to isolate the enzyme."

Wang and his colleagues found NG80-2 produced large amounts of a protein called LadA, which performed the first step in the degradation of long-chain alkanes.

Long-chain alkanes are used as lubricant and fuel oils, their existence chemically differentiating heavy oil from light oil which consists of shorter-chain alkanes. Heavy oil is usually more viscous and difficult to extract or remove.

The research results were published in this week's US journal Proceedings of National Academy of Sciences online; and the scientists suggest in their report that the protein is an "ideal candidate" for treatment of environmental oil pollution.

The sequence analysis also suggests the bacterial strain can adapt to many different environmental niches since it involves versatile metabolic processes, which add to its potential in many biotechnology applications.

Current microbial approaches to degradation of oil pollutants are of low efficiency, and mostly apply to light oil, according to Wang, professor and dean of TEDA School of Biological Sciences and Biotechnology at Nankai University.

"More importantly, they are used in a context that no definite knowledge about how the bacteria work is available," he said. "With the identification of this protein, we can upgrade it or alter it to various applications and improve efficiency of its performance."

The research team has started looking into the three-dimensional structure of the protein and tested it in a field experiment on oil pollutant degradation.

Wang believes a wider application of the protein would be realized in two to three years. In addition to oil pollutant removal, oil extraction is another potential field for its application, he added.

US Department of Energy data has shown that the microbial approach can improve oil extraction efficiency by 10 to 15 percent and sustain the development term of oil reserves by five to 10 years.

Science Daily, a Beijing-based newspaper, has reported that pilot field experiments at Shengli Oil Field had helped increase cumulative oil production by about 60,000 barrels by 2005.

But Han Xuegong, a retired professor at China National Petroleum Corporation Managers Training Institute, warns that laboratory success does not necessarily guarantee industrial usage. "Cost plays a crucial role," he said.

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