Binding of a nuclear factor to a consensus sequence in the 5' flanking region of zein genes from maize

The genomic organization of the zein structural genes and of regulatory loci influencing their expression suggests that control of zein gene expression will involve interactions between cis elements in the flanking DNA sequences and products from trans-acting genes. The interaction between fragments from the 5' flanking region of a zein gene and specific, double-stranded oligonucleotides with crude nuclear extracts from maize endosperm have been studied by nitrocellulose filter binding, gel retention and DNase I footprinting assays. Specific binding of a nuclear factor was observed and the exact position of the protein binding site was determined. The 22-nt binding site included 14 bp of a 15-bp sequence conserved in all zein genes.     

Bioactive polymers XXX. Immobilization of invertase on the diazonium salt of 4-aminobenzoylcellulose

Invertase was immobilized on diazotized 4-aminobenzoylcellulose. The optimum coupling conditions, namely enzyme concentration, time, and pH, were determined. The temperature and pH value for the maximum activity of the immobilized enzyme were determined and the apparent Michaelis constant was estimated.     

Spore production of Penicillium roqueforti by solid state fermentation: Stoichiometry, growth and sporulation behavior

The development of Penicillium roqueforti on buckwheat seeds proceeds roughly into four steps, involving a lag phase and three growth phases. First, it appears as a spore germination and external colonization of the grains by the mycelium. Then, mainly external sporulation and internal colonization of the seeds occur and finally internal sporulation takes place. The Stoichiometry of the growth and the sporulation is established. Kinetic experiments performed in a fixed bed reactor show that the growth of the microorganism (biomass production) may be estimated by the protein content of the medium. This growth occurs with a very low mu(max) value close to 0.030 h(-1). The chitin content of the medium is an indicator of the sporulation, just as the metabolic liquor (mainly water) produced during the course of a cultivation. The values of the observed respiratory quotient are close to those predicted by stoichiometry.     

Immobilization of microorganisms by adhesion: interplay of electrostatic and nonelectrostatic interactions

The adhesion of three microorganisms (Saccharomyces cerevisiae, Acetobacter aceti, and Moniliella pollinis) to different materials has been studied using various supports (glass, metals, plastics), some of which were treated by an Fe(III) solution. The surface properties of the cells were characterized by the zeta potential and an index of hydrophobicity; characterization of the supports involved surface chemical analysis (XPS) and contact angle measurements. Cell suspensions in pure water at a given pH were left to settle on plates; the latter were then rinsed and examined microscopically, Saccharomyces cerevisiae and A. aceti adhere to metals under certain pH conditions but do not adhere to any of the other materials tested unless it is previously treated by ferric ions; adhesion of these hydrophilic cells is essentially controlled by electrostatic interactions. Moniliella pollinis adhere spontaneously to glass and to polymeric materials, but its attachment is also influenced by cell-cell or cell-support electrostatic repulsions; near the cell isoelectric point, cell flocculation is competing with adhesion to a support.     

Continuous production of L-phenylalanine by transamination

L-Phenylalanine was produced continuously from L-as-partate and phenylpyruvate by transaminase from a newly screened Pseudomonas putida strain. The process was carried out with an isolated enzyme in homogeneous phase in an enzyme membrane reactor and with immobilized whole cells in a stirred tank reactor, respectively. Due to the difference in transport resistance, the productivity of the free enzyme in homogeneous phase (72 mmol/L h) was about 3 times higher than the productivity achieved using immobilized cells. However, a better stability of the biocatalyst was observed with immobilized cells.