Chemical Composition of Azotobacter vinelandii Cysts

Abstract

Cysts of Azotobacter vinelandii ATCC 12837 were germinated by exposure to 3.0 mM ethylenediaminetetraacetic acid (EDTA)-tris(hydroxymethyl)aminomethane buffer at pH 7.8, and their outer coats (exines) were purified by differential and isopycnic centrifugation. Electron micrographs of exine showed it to consist of multilayers of a three-membered sheet structure whose thickness was 7.0 to 7.5 nm. The inner, less electron-dense layer (intine) was also prepared from cysts by EDTA treatment, centrifugation, concentration, and dialysis. The exine consisted of 32% carbohydrate, 28% protein, 30% lipid, and 3.2% ash, with the ash comprised of 1.62% calcium, 0.02% magnesium, and 0.34% phosphorus. The amino acid composition of exine was similar to that of gram-negative bacterial cell walls. The intine consisted of 44% carbohydrate, 9.1% protein, 37% lipid, and 4.1% ash, with the ash comprised of 2.45% calcium, 0.02% magnesium, and 0.38% phosphorus. The carbohydrates of both exine and intine contained glucose, mannose, xylose, and rhamnose. Glucosamine and galactosamine were found only in the exines. The fatty acids consisted of normal, iso, and anteiso saturated fatty acids with 10 to 18 carbon atoms and mono-unsaturated C1l, C1,s, and C18 fatty acids. The exines contained mostly bound lipid, but intines contained primarily free lipid.Cells of Azotobacter vinelandii undergo a morphogenetic process which leads to the pro-486

Fatty acids in phospholipids of cells, cysts, and germinating cysts of Azotobacter vinelandii

“…Total extractable lipid accounted for 10.8% of the dry weight of whole cells, a result corresponding to that published by Kaneshiro and Marr (7). Total extractable lipids accounted for 17.5% of the dry weight of cysts, which is close to the result of Lin and Sadoff (10). The principal fatty acids in cysts were palmitic, palmitoleic, cis-9,10-methylene hexadecanoic, cis-vaccenic, and lactobacillic acids; the minor fatty acids (less than 5% each) were myristic (014:0) and octadecanoic (Cl8o) acids.…”

Mannuronan C‐5 epimerases and cellular differentiation of Azotobacter vinelandii

“…With regard to chemical composition, the exine material contains roughly equal amounts of protein, lipid and carbohydrates, whereas the intine consists of about 40% each of carbohydrates and lipid, and little protein. Some 40% and 72% of the carbohydrate in exine and intine, respectively, consists of polyuronic acids (Lin and Sadoff, 1969). These exist as alginate polymers of heteropolymeric (MG) and homopolymeric (GG or MM) blocks.…”

Morphogenesis of Cysts in Azotobacter vinelandii

“…Upon germination, these cysts recycle into vegetative cells. Previous studies from this laboratory have been concerned with the chemical composition and the ultrastructure of the two cell forms (6,(8)(9)(10). In this report we will present an electron microscopic study of the progressive morphological events that occur in the transition from vegetative cells to cysts.…”