ABSTRACT
Acetobacter xylinum produces highly crystalline cellulose extracellularly using glucose as a carbon source. The polymer formed is free of other biogenic compounds, separable in a simple way and characterized by its high water-absorption capacity. Stepwise solvent exchange from water to unpolar solvents leads to a drastic decrease of the water content of the bacterial cellulose without decrease of the highly swollen and activated state. Heterogeneous as well as homogeneous derivatizations, e.g. carboxymethylation, silylation and acetylation, were performed on the wet or dried biopolymer. Furthermore, different methods for formation of hollow fibres during biosynthesis were investigated. Such tubes may have applications as biocompatible material in medicine.
Subject(s)
Acetobacter/metabolism , Biocompatible Materials , Cellulose , Industrial Microbiology , Absorption , Acetylation , Alkylation , Biopolymers , Carbohydrate Conformation , Carboxymethylcellulose Sodium/chemical synthesis , Cellulose/analogs & derivatives , Cellulose/biosynthesis , Cellulose/chemical synthesis , Cellulose/chemistry , Cellulose/isolation & purification , Glucose/metabolism , Methylation , Organosilicon Compounds , Spectrophotometry, Infrared , Trimethylsilyl Compounds/chemical synthesis , WaterABSTRACT
The water permeabilities of 3174 astomatous, isolated cuticular membranes from Citrus aurantium L. leaves were studied. Trees were grown in environmental chambers at temperatures ranging from 15 to 35° C and humidities of 50% and 90%. Photosynthetically active radiation was 500-1000 µmol photons·m(-2)· s(-1). The different growing conditions had no effect on the water permeability of the membranes. However, storing isolated cuticular membranes at 8° C for up to 112 weeks decreased their water permeability, and it is argued that this is a consequence of the healing of defects between wax crystallites, and also indicates the dynamic nature of cuticular waxes.
ABSTRACT
Deoxyribonucleic acid (DNA)-DNA hybridization and physiological studies on 15 strains of S. sciuri subsp. lentus and 4 strains of S. sciuri subsp. sciuri demonstrated that species rank should be conferred on these subspecies. Strain ATCC 29070, the type strain of S. sciuri subsp. lentus, is proposed as type strain of S. lentus. An emended description of this strain is given.
