Diversity of Lipase-Producing Microorganisms from Tropical Oilseeds Elaeis guineensis, Ricinus communis, and Jatropha curcas L. from Costa Rica.

Tropical oleaginous seeds are an unexplored source for the discovery of novel lipolytic microorganisms, which could be applied to the bioremediation of agro-industrial oily wastes and solve numerous environmental issues. Such wastes hold potential to be revalorized towards a variety of products through microbial bioremediation. In this study, we investigate the microbial diversity and lipase activity from bacterial and fungal isolates obtained from the oil seeds of Elaeis guineensis, Ricinus communis, and Jatropha curcas L. from Costa Rica. A total of 27 strains were confirmed as lipase-producing strains via fluorogenic and colorimetric agar plate assays. The diversity of the isolates comprises 12 fungal ascomycetes from the genera Aspergillus and Fusarium and 15 bacterial isolates classified into four genera: Serratia, Proteus, Pseudomonas, and Bacillus. Microbial isolates from E. guineensis showed the highest diversity of lipolytic microorganisms (6 genera) followed by J. curcas (4 genera) and R. communis (2 genera). Isolates showing the highest activity in agar plates were tested further by submerged fermentation and the specific lipase activity was measured with 4-nitrophenyl laurate as substrate. Accordingly, the highest specific lipase activity was demonstrated by Bacillus pumilus B5 (24.98 U mg), Serratia marcescens B10 (17.65 U mg), Pseudomonas mendocina B16 (8.62 U mg), and Bacillus pumilus B1 (5.72 U mg) in submerged fermentation. These findings indicate the presence of a specialized microbial diversity in tropical oil seeds and highlight their potential to be applied in the bioremediation of agro-industrial oily wastes.