Production of l-lactic acid from a green microalga, Hydrodictyon reticulum, by Lactobacillus paracasei LA104 isolated from the traditional Korean food, makgeolli

The freshwater microalga, Hydrodictyon reticulum, that contained 47.5% reducing sugars including 35% glucose was used as substrate for the production of l-lactic acid (LA) by LA-producing bacteria. Lactobacillus paracasei LA104 was selected for fermentation in a 5-l fermentor since it was able to grow at pH 3, 60 g LA/l, 200 g glucose/l, 125 g NaCl/l, and 45 °C and produced over 97.3% optically pure l-lactic acid with glucose as a substrate. Simultaneous saccharification and cofermentation from H. reticulum to l-LA using LA104 was investigated in a jar fermentor. The yield reached 46 g/100 g H. reticulum dry material, with a final concentration of 37.11 g/l and a productivity of 1.03 g/l/h. This is the first report of the production of l-LA from a microalga, and H. reticulum could be a potential feedstock for large-scale production of l-LA by LA104.