The properties of the biotin uptake system of Lipomyces starkeyi IAM 4753 were investigated in proliferating and nonproliferating cells from the standpoint of explaining the characteristics of the biotin-requiring property of the organism in a medium with a pH from 5.5 to 6.5. The rate of biotin uptake was linear with time for at least the first 6hr. Uptake of 14C-biotin showed the system to be an aeration- and energy source-dependent process. This was confirmed by the almost complete inhibition of biotin uptake with 1mM of 2, 4-dinitrophenol, potassium cyanide, and sodium azide. Biotin uptake is pH-dependent, and the optimum condition for uptake is a pH of 4.2. Biotin uptake is operative between a pH of 5.5 and 6.5, and thus L. starkeyi IAM 4753 can grow in a medium with a pH from 5.5 to 6.5, when biotin is supplemented. The uptake of biotin by the cells is influenced by the biotin concentration in the medium employed. The greatest uptake was observed when the cells were grown in a minimal medium without any supplementation of biotin. Apparent activity for biotin uptake per mg dry cell was considerably influenced by culture age. The amount of 14C-biotin taken up by mg dry cell harvested during the logarithmic phase was the highest, decreasing gradually as the growth phase proceeded.
The guanine plus cytosine (GC) contents of a collection of phytopathogenic coryneform bacteria, determined by buoyant density equilibrium centrifugation in CsCl gradients, fall in the range of about 65 to 73%. By means of DNA-DNA segmental homology determinations, it was possible to show that Corynebacterium fascians is not related genetically to any of the other phytopathogenic coryneforms. A minor partial homology groups (but not very firmly) Corynebacterium insidiosum, C. michiganense, and C. sepedonicum into one genetic cluster and C. poinsettiae, C. betae, C. flaccumfaciens, and C. ilicis into another; these genetic groupings coincide somewhat with others based on serology, morphology, and cell wall composition.
This report describes the first comparative study of petroleum-degrading yeasts, fungi, and bacteria, and their ability to degrade a mixed hydrocarbon substrate. The mixed hydrocarbon substrate employed contained aliphatic, alicyclic, aromatic, and polynuclear aromatic hydrocarbons. The yeasts which were studied included Sporobolomyces sp., Candida sp., C. tropicalis, Hansenula beijerinckii, Aureobasidium pullulans, Rhodotorula glutinis, and R. rubra, and the fungi, Cladosporium resinae, Aspergillus spp., Penicillium spp. The bacterial species were Pseudomonas sp., P. aeruginosa, Vibrio spp., Acinetobacter spp., Leucothrix mucor, Nocardia asteroides, N. corallina, Rhizobium meliloti, R. leguminosarum, and a coryneform. Most of the bacteria and all of the yeasts and fungi were isolated from Chesapeake Bay. Normal alkanes were found to be less susceptible to degradation by bacteria and yeasts as the carbon chain length of the hydrocarbon increased from 10 to 20. Results obtained for some of the fungi showed that there was little correlation between chain length of normal alkane and susceptibility to biodegradation. Cumene, naphthalene, phenanthrene, pristane, 1, 2-benzanthracene, perylene, and pyrene were found to be degraded by microorganisms. In general, the patterns observed for hydrocarbon utilization were similar for the bacteria, yeasts, and fungi. However, the utilization of hydrocarbons by individual isolates varied significantly. Such information may prove useful in assessing the hydrocarbon-degrading potential of microorganisms.
Several floc-forming bacteria and phenol-decomposing bacteria were isolated from a phenol-adapted activated sludge. Strain No. 12 was the best floc-former and the ratio of flocculated cells to total cells was 90% or more. A model floc was formed by the mixed culture of the strain No. 12 and No. 3, which was one of representative strains of phenol-decomposing bacteria. This model floc can successfully decompose such a high concentration of phenol as 700ppm, though the strain No. 3 in pure culture did not show any detectable phenol decomposition or did not even grow at that concentration of phenol.
As determined by enzyme levels and by differential rate of enzyme formation, the synthesis of α-amylase and glucoamylase by Clostridiumacetobutylicum is under separate regulatory systems. Induction of α-amylase occurs when starch is the carbon source while induction of glucoamylase accompanies growth with glucose. Minimal production of both enzymes is associated with growth on fructose, and intermediate levels result from growth with maltose. While both α-amylase and glucoamylase are elaborated into the culture fluid during the logarithmic growth phase, 41-44% of total amylase and 22-33% of total glucoamylase remain associated with the bacterial cells. Studies involving cell fractionation, cell washing, and pH-dependent adsorptions indicate that cell-associated α-amylase and glucoamylase are localized primarily with the surface of the cells and only to a small extent with the intracellular region.