Bioprocess design and economic analysis for the commercial production of environmentally friendly bioinsecticides from <i>Bacillus thuringiensis</i> HD‐1 <i>kurstaki</i>

Abstract

A production process for B. thuringiensis (Bt) bioinsecticides was designed in detail, including alternative batch, low-density fed-batch (LDFB), and high-density fed-batch (HDFB) fermentation configurations. Capital and operating costs, as well as profitability based on simple rate of return, were performed using a purpose-written FORTRAN program, explicitly analyzing production of a water-based flowable product used in forestry applications. The total capital cost was 18 million dollars (Canadian dollars) for a stand-alone plant with base-scale capacity of 3 x 10(7) billion international units (BIU)/year. Raw material costs amounted to 1.5 million dollars yearly, of which approximately half was for formulation ingredients. Per-unit production cost rose sharply for scales of less than 1 x 10(7) BIU/year, but was little affected by scale above 3 x 10(7) BIU/year. Product cost was much lower at all scales for a LDFB as opposed to batch fermentation process, but HDFB gave relatively little additional cost benefit. Profitability analysis performed by co-varying scale and selling price showed that break-even occurred at a price of 0.45 dollars/BIU for a batch process at base scale, while with LDFB fermentation the same production volume sold at 0.35 dollars/BIU gave a 12% rate of return. Since the assumed base scale would represent 8-15% of current world Bt bioinsecticide production, based on value or volume, it was concluded that profitability would require some or all of the following elements: targeting higher-value markets such as disease vector control, in addition to forestry; a potentially lower plant capacity (although at least 1 x 10(7) BIU/year;) and coproduction of other large-volume microbial products to absorb capacity and match bioinsecticide output to market demand.