doi:10.1038/nindia.2015.91 Published online 9 July 2015
Researchers have synthesized an extracellular biopolymer by growing a mutant strain of the bacterium Acinetobacter haemolyticus in a nutrient-rich culture medium1. They found that the biopolymer effectively removed anionic pollutants such as phosphate from wastewater, making it potentially useful as an adsorbent for cleaning industrial wastewater.
The researchers extracted the biopolymer by growing the bacterium in a culture medium containing peptone, dextrose and various inorganic salts. They produced an off-white nanoporous biopolymer that had a fluffy texture by mixing the extracted biopolymer with chilled ethanol and then washing and drying it.
The scientists measured the efficacy of the biopolymer in removing phosphate from 60 wastewater samples and found that it removed 60% of the dissolved phosphate from all the samples after 4 hours.
Structural analysis revealed that the biopolymer consisted of polysaccharides, proteins, uronic acids and pyruvic acid. These biomolecules help the biopolymer to bind to anionic phosphate through electrostatic interactions. The researchers also found that the nanoporous biopolymer had a high surface area, which provides many binding sites on the surface, making it conducive for efficient phosphate binding.
The phosphate-binding ability of the biopolymer was highest in an acidic medium and decreased with increasing pH.
The researchers say that the high thermal stability and shear-thinning behaviour of the biopolymer make it suitable for industrial applications.