Lactobacillus amylovorus, a New Starch-Hydrolyzing Species from Cattle Waste-Corn Fermentations

Abstract

Several starch-hydrolyzing strains of Lactobacillus Beijerinck 1901 were isolated from cattle waste-corn fermentations. The isolates were facultatively anaerobic, gram-positive, nonmotile, nonsporeforming, rod-shaped organisms that grew singly and in short chains, produced lactic acid and small amounts of acetic acid but no gas from glucose, and did not exhibit oxidase-, catalase-, or nitrate-reducing activities. Growth occurred at 45°C but not at 15°C. dl-Lactic acid was synthesized from glucose. An extracellular amylolytic enzyme was formed. The organisms fermented amygdalin, cellobiose, esculin, fructose, galactose, glucose, maltose, mannose, salicin, starch, sucrose, and trehalose. Some strains fermented mannitol and lactose. Arabinose, gluconate, melezitose, melibiose, raffinose, rham-nose, ribose, and xylose were not fermented. The average guanine-plus-cytosine content of the deoxyribonucleic acid was 40.4 mol%. Reassociation values of 15% or less were obtained with the deoxyribonucleic acids of the starch hydrolyzers and those of the type strains of Lactobacillus acidophilus (Moro) Hansen and Mocquot 1970; Lactobacillus jensenii Gasser, Mandel, and Rogosa 1970; and Lactobacillus leichmanii (Henneberg) Bergey et al. 1923. The new species was differentiated from the three recognized species on the basis of starch fermentation, vitamin requirements, guanine-plus-cytosine contents, and stereoisomerism of lactic acid produced. It was concluded that these organisms represent strains of a hitherto unrecognized species for which the name Lactobacillus amylovorus is proposed. The type strain of L. amylovorus is NRRL B-4540.