Abstract
Today, biofuels represent a hot topic in the context of petroleum and adjacent products decrease. As biofuels production increase, so does the production of their major byproduct, namely crude glycerol. The efficient usage of raw glycerol will concur to the biodiesel viability. As an inevitable waste of biodiesel manufacturing, glycerol is potentially an attractive substrate for the production of value-added products by fermentation processes, due to its large amounts, low cost and high degree of reduction. One of the most important usages of glycerol is its bioconversion through microbial fermentation to value-added materials like 1,3-propanediol and citric acid. There is a considerable industrial interest in 1,3-propanediol and citric acid production based on microbial fermentations, as it seems to be in competition with traditional technologies utilized for these products. In the present work, yields and concentrations of 1,3-propanediol and citric acid registered for different isolated strains are also described. Microbial bioconversion of glycerol represents a remarkable choice to add value to the biofuel production chain, allowing the biofuel industry to be more competitive. The current review presents certain ways for the bioconversion of crude glycerol into citric acid and 1,3-propanediol with high yields and concentrations achieved by using isolated microorganisms.