Seawater Sludge Secrets: A Protein's Role in Granule Strength

Scientists have found a key protein in the sticky stuff that holds together sludge granules in seawater. This protein might be the reason these granules stay strong and can remove phosphate from water. The granules were grown in a special reactor using seawater and acetate, a common carbon source. The main microbe in these granules was "Candidatus Accumulibacter, " which was identified using a technique called fluorescent in-situ hybridization. The researchers found a protein with a molecular weight of 74. 5 kDa in the sticky matrix of the granules. This protein is likely made by the Accumulibacter species and is similar to other proteins that form protective layers in some bacteria. Interestingly, the gene for this protein is next to a set of genes that might help the protein get exported out of the cell. To confirm that this protein is indeed on the outside of the cells, the researchers made antibodies against a unique part of the protein. These antibodies lit up the protein in microscope images, showing that it forms dense structures within the microcolonies of Accumulibacter and larger fibers around them. This protein seems to play a big role in the structure of the granules. To find more proteins like this in the sticky matrix, the researchers say we need better methods for extracting and imaging them. This discovery could help us understand how to make better biofilms and granules for wastewater treatment.