Inhibition of bacilli in industrial starches by nisin

The properties of Bacillus coagulans and of other bacilli that contaminate paper and paperboard manufacturing processes were investigated under simulated industrial conditions. Nisin (0.05 to 0.125 μ2g ml⁻¹) blocked growth of indigenous bacilli that contaminate sizing starches. B. coagulans starch isolates, B. licheniformis, B. amyloliquefaciens, and B. stearothermophilus grew at ≥250C in industrial starch and produced α2-glucosidase and cyclodextrins. The industrial isolates and reference strains of B. amyloliquefaciens, B. cereus, B. coagulans, B. flexus, B. licheniformis, B. pumilus, B. sporothermodurans, B. stearothermophilus and Alicyclobacillus acidoterrestris were inhibited by ≤20.125 μ2g of nisin on agar. B. coagulans and B. stearothermophilus were similarly inhibited by ≤20.025 μ2g of nisin ml⁻¹ and by 3 μ2g of the biocide DBNPA ml⁻¹ in industrial starch. B. licheniformis and B. amyloliquefaciens strains were less sensitive. About 40% of nisin added to starch was retained after cooking. Fifty percent of the nisin remained active after 11 h of storage at 60C. The results show that nisin has potential as a preservative for modified industrial starches. Journal of Industrial Microbiology & Biotechnology (2001) 26, 107–114.