Microbial conversion of waste baklava syrup to biofuels and bioproducts

In Turkey, approximately 17.5 million liters of waste baklava syrup (WBS) are generated annu-ally. WBS contains a high amount of sugar; however, it does not find any application. In this study, microbial conversion of WBS to biofuels and bioproducts was investigated. The experi-ments were performed in shaking flask cultures. WBS was not subjected to any hydrolysis process and was directly used as substrate in the medium, since it was in liquid form. The total sugar content of WBS was determined as 870 g/L. At the optimal concentrations of WBS, 38.6 g/L citric acid by Aspergillus niger, 27.3 g/L levan by Zymomonas mobilis and 8.9 g/L lipids by Rhodotorula glutinis could be produced. The amounts of ethanol produced by S. cerevisiae and Z. mobilis were 129 and 75.2 mL/L, respectively. The maximum absorbances for yellow, red and orange pigments which were produced by Monascus purpureus were determined as 0.7768, 0.928 and 0.835, respectively. Evaluating WBS as a substrate in microbial fermentation studies can contribute to reducing both the medium cost and the environmental pollution problem. This is the first report about the use of WBS as a substrate in microbial studies.