According to the text, Statins produced by the yeast Monascus purpureus have been commercialised as blood-cholesterol lowering agents. They act by competitively inhibiting the enzyme responsible for the synthesis of cholesterol. In contrast, Ethanol is produced by Saccharomyces cerevisiae, Streptokinase by Streptococcus, and Citric acid by Aspergillus niger.