Using the Juice of Water Lettuce ( Pistia stratiotes ) as Culture Medium to Increase the Cell Density and the Production of Microbial Lipid

Water lettuce (Pistia stratiotes) is one of the most well-known aquatic weeds as it causes problems in watercourses all over the world. This invasive species is fast-growing and thus has the potential for its use in preparing growth medium of microorganisms. Toward it, the pretreatment and enzymatic saccharification are positively the decisive processes. But there are other crucial processes, which are usually ignored by researchers. To the best of my knowledge, this presented work is the first time discovering that the juice obtained from water lettuce is valuable. Except for sterilization, no treatment is needed for the water lettuce’s juice and it can be directly served for cell growth. For Escherichia coli, Saccharomyces cerevisiae, Pichia pastoris, Bacillus subtilis, Lactococcus Lactis, Lactobacillus rhamnosus, and Lactobacillus plantarum , the cell density in the broth of water lettuce’s juice as the only carbon source is 10–60% higher than that in LB, YPD, BHI, M17, MRS. We then examined the production of microbial lipid by YM prepared in the juice of water lettuce. In comparison to commercial medium YM broth, the YM with juice caused 84% increase in the production of microbial lipid. A simple process of collecting juice notably increased productivity.