Using a model virus, bacteriophage MS2 against Escherichia coli, virus sorption on coal was investigated. Batch sorption data show that virus sorption is influenced by H/C and H/O ratios of coal, and the presence of other viruses, bacteria, and organic pollution in the water. Virus removal in a continuous flow coal column is affected by column height and input virus concentration. Application of virus sorption on coal in water treatment is discussed.
A mechanistic mathematical model is developed for Streptococcuscremoris HP which uses the intracellular substrate concentration as a state variable for the fermentation system. The concept of a threshold intracellular substrate concentration and a new model of product inhibition are introduced to account for a pronounced lag phase and a strong metabolic product inhibitory effect. Parameters for the model are determined from experimental data from seven batch runs with widely varying initial and final conditions. Statistical tests and comparisons with another model are carried out. A possible method of optimisation is discussed in terms of the developed model.
With all the media investigated citric acid yield increased with the age of culture of Aspergillus niger 599. The extent of this yield was related to the composition of the medium but not to the mycelial growth or spore formation. With most media, this was also the case of the extracellular polygalacturonase activity. No pectin-methylesterase was formed either in the fermentation broths or the mycelia. The effect of addition of pectin, methanol, or pectin+methanol to the culture media on the production of the metabolites was investigated. The results indicated a consistent relationship between citric acid production and both extracellular and intracellular polygalacturonase activities in molasses media. The ratio of extracellular to intracellular polygalacturonase activity varied from one medium to another, and with the age of culture of the same medium.
Host functions involved in multiplication of single-stranded DNA phages S13, φR, and φKh-1 were examined using various DNA replication mutants of E. coli. When the phage-resistant bacteria were to be tested, glycine spheroplasts or Ca2+-treated cells were transfected by the phage DNA. Replication of S13 and φR required host dnaB, dnaC(D), dnaE, dnaG, and dnaZ gene products. On the other hand, growth of φKh-1 was dependent on cellular dnaE, dnaF(nrdA), dnaG, and dnaZ functions, but not on dnaB and dnaC(D) activities. Multiplication of these phages absolutely relied on host rep function. Based on these host factor requirements, relationship among single-stranded DNA phages was discussed. In addition, host range and antigenic property of φKh-1 were compared with those of the related phages.
Gnotobiotic cultures of Entodinium caudatum were prepared from the clones of this protozoon. The organism grew well with any of the bacterial species investigated, irrespective of shape, origin, and gram-staining property. The cultures with Escherichia coli, as well as Streptococcusbovis, were maintained for over 2 months. The protozoa free from living bacteria were prepared from the gnotobiotic cultures established. These axenic protozoa could be kept alive in the presence of dead bacterial cells for up to 3 weeks, but their growth was extremely slow and the population densities maintained were much lower than those in the cultures with living bacteria.