Promising Talents Of A Wild Bacterium

A wild strain of E. coli possessing completely original properties has been discovered in shea cake, a residue of a tropical food industry used in cosmetics, by IRD scientists working in microbial biotechnology found the strain, designated “ C2 ”, had the ability to transform certain polluting aromatic acids into other, non acid, aromatic compounds (including phenol and guaicol) which are highly prized for both the chemical and food-processing industry. The type strain of E. coli cannot do this.

The bacterium Escherichia coli is present in the lower intestine of most warm-blooded animals. The genome structure of this unicellular organism has been known for several years. Geneticists, microbiologists and molecular biologists use E. coli commonly as an experimental model. If changed genetically, this bacterium can be used to make a variety of proteins, such as insulin or human growth hormone. Industry can use it, but only after genetic modification, as the basis of a system for producing commercially viable substances.

The food industry is very keen to find organisms that can produce natural compounds which might replace synthetic ones currently used. Artificial anti-oxidant food preservatives are a case in point. The industry is trying increasingly to move away from these in favour of anti-oxidizing agents of biological origin.

This is the first E. coli strain ever identified which has a natural talent, inscribed in its phenotype, for converting toxic compounds such as tannins and certain aromatic compounds into potentially useful agents for industry. The discovery opens up great perspectives for development. By comparing the genome of the type strain of E. coli with that of C2, it becomes possible to find out what extra factor exists in this wild strain’s genome structure enabling it naturally to perform the conversion. There are two hypotheses: the candidate part of the genome is present in the known strain but is not expressed; or the wild strain bears an extra portion of genome.

The molecular biology techniques employed in attempts to decide on one or other theory have not hitherto succeeded in determining the structure of the protein responsible for this previously unknown property. More advanced sequencing methods should be deployed before this wild strain will reveal its closely guarded secrets.

Once the anticipated results on this bacterial strain have been obtained, the industrial production could be devised of high-added-value compounds which could legitimately be labelled as “natural “ products. This discovery could, in the more immediate term, be helpful for African countries of the Sudano-Sahelian regions, the only part of the world where the tree which produces shea cake grows. E. coli ’s wild strain is equipped with degradation abilities could conceivably be used for biological treatment of the residues of fabrication of this product which is sure to develop strongly in the near future.2.

(1) Research work conducted by th IRD (Research Unit on Microbial Biotechnology) at Marseille, in a joint structure (IFR-BAIM), in partnership with an INRA team (UMR-BCF, Marseille) and scientists from Burkina Faso (CRSBAN, Ouagadougou University) and Tunisia (CBS, Sfax).

(2) Shea cake is currently used mainly by the cosmetics industry but has recently been authorized as a cacao-butter substitute for making chocolate.

Institut de Recherche pour le Développement, Paris (IRD). June 2002.