Bacterial fermentation of Lemna sp. as a potential substitute of fish meal in shrimp diets

Lemna sp. flour was fermented with bacteria as a source of protein for the preparation of white leg shrimp diets. Pediococcus pentosaceus was isolated from Litopenaeus vannamei and Litopenaeus stylirostris juveniles and characterized with biochemical (Gram stain, hemolytic activity, extracellular enzymatic activity, hydrophobicity, bacterial growth kinetics, salt tolerance, and cell count) and molecular (16S ribosomal gene) tests. The presumptive bacillus (Ba4), previously isolated and characterized, was identified as Bacillus pumilus. P. pentosaceus and B. pumilus were used in the fermentation of duckweed flour, with different percentages of molasses and humidity. Both bacteria showed high growth in fermented flour. In addition, the fermented flour showed high protein content and a significant decrease in crude fiber, lipids, ashes, and phytic acid. The concentration of tannins remained unchanged. Fermentation of Lemna sp. flour improves its nutritional value and suitability as an alternative protein source in formulated diets for white shrimp L. vannamei.    Key words: Fermentation, Lemna sp., Pediococcus pentosaceus, Bacillus pumilus, Weisella sp., molasses.