Marine photosynthetic bacteria can produce high molecular weight bioplastics
Science and Technology Daily, Tokyo, August 23 (reporter Chen Chao) Japan Riken Institute of environmental resources Science research center of Kuiji Diguda led a research team recently found that Marine photosynthetic bacteria (referred to as photosynthetic bacteria) can produce high molecular weight hydroxyl acid (PHA).
PHA is a kind of bioplastic produced in the body of microorganisms, which is a storage substance of carbon and energy stored by organisms to prevent nutritional deficiencies. Due to its biodegradability and bioadaptability, PHA can be used as an alternative material for petroleum-based plastics. So far, almost all reports of photophythmic bacteria producing PHA have been freshwater photophythmic bacteria. This is the first time that the research team conducted an experiment using seawater in a medium with high salt concentration to reduce the mixing of other bacteria.
The research team first used three strains of Marine photosynthetic bacteria red sulfur bacteria and nine strains of red non-sulfur bacteria to verify PHA production performance. They cultured 12 strains of photosynthetic bacteria with acetic acid and sodium bicarbonate added to the nitrogen-deficient medium, and then compared the PHA production of each strain in the normal medium with that in the nitrogen-deficient medium using a gas layer analyzer. The results showed that PHA production of 3 red sulfurous bacteria increased in nitrogen-deficient medium and existed in granular form. 6 strains of red non-sulfur bacteria showed high PHA production in normal medium, which was about 20% to 30% of the body weight of dry bacteria. No significant increase in PHA production was found in nitrogen-deficient medium. The PHA production verification test of 1 strain of red non-sulfur bacteria using artificial seawater medium showed that red non-sulfur bacteria did not develop in artificial seawater. After adding yeast extract to the medium, although bacterial proliferation was visible, no PHA was produced. When acetic acid was added to artificial seawater as a carbon source, it was found that red non-sulfur bacteria produced PHA.
There are reports that the molecular weight of PHA produced by microorganisms is about 300,000. However, the research team extracted and refined the PHA produced by photosynthetic bacteria and determined the PHA number with average molecular weight by gel permeation chromatography. It was found that the molecular weight of PHA synthesized by some red sulfur bacteria and red non-sulfur bacteria was 2 to 3 times higher than previously reported.