Substrate Effect on 2,3-Butylene Glycol Production by Rhizopus nigricans and Penicillium expansum

Rhizopus nigricans and Penicillium expansum produced 2,3-butylene glycol which accumulated in natural and artificial media with time. Mycelial mats of P. expansum decreased the quantity of a diacetyl substrate and converted part of this substrate into acetylmethylcarbinol (AMC) and 2,3-butylene glycol. Mycelial mats of P. expansum also decreased AMC substrate with the formation of 2,3-butylene glycol. 2,3-Butylene glycol decreased slightly during incubation with the fungal mat. The formation of AMC was suppressed significantly by cysteine and ascorbic acid.     

Environmental Stresses on Spore Populations of Bacillus stearothermophilus

Heat-shocking spores at 110 C in 20% sucrose solutions decreased the percentage of the rough variant in a mixed population (rough and smooth variants) of strain M. Heat-shocking spores of the rough variant of strain NCA 1518 in 20% sucrose produced a decline in the number which germinated, whereas the smooth variant of strain NCA 1518 increased in the number which germinated. By the use of phase microscopy and plate counts, from the same incubated spore suspension in distilled water, heat-induced dormancy was demonstrated at 52 C. Dormancy also occurred in 20% sucrose solutions when held at room temperatures. Heat-shocking spores of strain M in 20% sucrose solutions and plating immediately after 24- and 48-hr holding periods at 25 C produced a decline in the total population with the percentage of rough variant increasing with time. A second heat shock produced only an increase in the rough variant.