Non-feed application of rendered animal proteins for microbial production of eicosapentaenoic acid by the fungus Pythium irregulare

Authors: LIANG, YI - Iowa State University; Garcia, Rafael; Piazza, George; WEN, ZHIYOU - Iowa State University

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2011
Publication Date: 11/23/2011
Citation: Liang, Y., Garcia, R.A., Piazza, G.J., Wen, Z. 2011. Non-feed application of rendered animal proteins for microbial production of eicosapentaenoic acid by the fungus Pythium irregulare. Journal of Agricultural and Food Chemistry. 59(22):11990-11996.

Interpretive Summary: The health promoting omega-3 fatty acids found in fish oils can be produced by some microorganisms. Microbe produced omega-3’s can be used to fortify human food, or can be used in animal feed to produce items such as omega-3 enhanced eggs, meat or milk. Previously, we reported on a fungus that is a good producer of one important type of omega-3 fatty acid. It was shown that the sugar normally fed to this fungus can be replaced by a waste product from biodiesel production. In the present study, we showed that another substance used to grow the fungus can be replaced by an experimental ingredient we produced. This ingredient is made of meat and bone meal, a by-product of meat processing, which we have digested and processed in the laboratory. This ingredient successfully replaced an expensive ingredient that is normally required to grow the fungus and produce the omega-3 fatty acid. These results demonstrate a value added use for meat and bone meal, and a method for lowering the cost of omega-3 fatty acid production.

Technical Abstract: Rendered animal proteins are well suited for animal nutrition applications, but the market is maturing, and there is a need to develop new uses for these products. The objective of this study is to explore the possibility of using animal proteins as a nutrient source for industrial microorganism fermentations. Two microorganisms capable of producing omega-3 polyunsaturated fatty acids were tested; the microalga Schizochytrium limacinum and the fungus Pythium irregulare. In order to be absorbed by the microorganisms, the proteins needed to be hydrolyzed into small peptides and free amino acids. The utility of the protein hydrolysates for microorganisms depended on the hydrolysis method used and the type of microorganism. The enzymatic hydrolysates supported better cell growth performance than the alkali hydrolysates did. P. irregulare displayed better overall growth performance on the experimental hydrolysates compared to S. limacinum. When P. irregulare was grown in medium containing 10 g/L enzymatichydrolysate derived from meat and bone meal or feather meal, the performance of cell growth, lipid synthesis and omega-3 fatty acid production was comparable to the culture using commercial yeast extract. The fungal biomass derived from the animal proteins had 26-29% lipid, 32-34% protein, 34-39% carbohydrate, and less than 2% ash content. The results show that it is possible to develop a non-feed application for rendered animal protein by hydrolysis of the protein and feeding to industrial microorganisms which can produce omega-3 fatty acids for making omega-3 fortified foods or feeds.