Submitted to: New Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 31, 2011
Publication Date: October 1, 2011
Citation: Solaiman, D., Garcia, R.A., Ashby, R.D., Piazza, G.J., Steinbuchel, A. 2011. Rendered-protein hydrolysates for microbial synthesis of cyanophycin biopolymer. New Biotechnology. 28(6):552-558. Interpretive Summary: Meat and Bone Meal (MBM) is a large-volume byproduct of the animal rendering industry. This byproduct has historically been used in animal feed applications. However, currently many nations have developed legislation that has dramatically curtailed the use of MBM (especially that derived from ruminant animals such as cows, goats, sheep, etc.) in animal feed. The regulatory measures are taken to alleviate consumer concerns regarding the development and transmission of certain diseases. Because MBM is produced in such large amounts and since many governments are placing restrictions on the typical uses of MBM, new outlets are necessary to help MBM maintain its value. As its name indicates, MBM is composed of finely ground bits of meat and bone that have been thoroughly dried and powdered. The presence of meat in the MBM dictates that the material contains a high concentration of protein whose building blocks (amino acids) can be utilized for new applications. Cyanophycin (CP) is a fermentation-derived material that is normally made by a specific strain of bacteria (Cyanobacteria) and is composed of 2 distinct amino acids (aspartic acid and arginine). It has been documented to be a potential substitute for petroleum-based materials especially in the removal of metal ions in the water treatment industry. We have used two different methods, one involving pH manipulation and one involving enzymes, to break the proteins in MBM into small pieces. We proceeded to characterize the resultant material (called peptone) with respect to the type and absolute amino acid content, and to use the peptone as a substitute amino acid source (in place of the more commonly used, expensive Casamino acids) in the fermentative production of CP. A genetically altered strain of E. coli was used in the experiments because of its propensity to grow into large cell densities. In this study we were successful in showing that MBM can be used as a source of amino acids for the microbial production of CP and although not yet optimized, will ultimately provide a new, non-food outlet for MBM.
Technical Abstract: Cyanophycin is a poly(arginyl-aspartate) biopolymer produced and stored intracellularly by bacteria. Cyanophycin has been proposed as a renewable replacement for petrochemical-based industrial products. An abundant source of amino acids and nitrogen such as in the form of protein hydrolysates is needed for the biosynthesis of cyanophycin. Rendered proteins are largely used as a feed supplement in animal husbandry and aquaculture. New uses would expand the market size of this class of protein coproducts. We prepared and thoroughly characterized the hydrolysates of meat & bone meal, and proceeded to demonstrate for the first time that these hydrolysates could be used in the fermentative production of cyanophycin. Using the enzyme-hydrolyzed meat & bone meal preparation, we obtained crude cyanophycin product at 35% level of that produced using the reference Casamino acids. Polyacrylamide-gel electrophoresis of the cyanophycin under denaturing conditions showed the molecular weight of the isolated polyamide at 24 kDa. Our results open a new avenue for the utilization of rendered protein coproducts to produce the cyanophycin biopolymer.