title: Characterization of Azotobacter vinelandii aggregation in submerged culture by digital image analysis.
abstract: A simple and accurate method for determining the distribution of sizes of single cells and aggregates of Azotobacter vinelandii by image analysis has been developed. A staining procedure using methylene blue helps to enhance the contrast between aggregates and background without altering aggregate size distribution. Sample dilution affected the distribution of the population and therefore should be avoided. Mixing and aeration conditions during culture play an important role in the aggregation of A. vinelandii. Cells grown under mild mixing conditions (unbaffled flasks) presented a thick slime layer and formed aggregates of up to 35 microm of average equivalent diameter. In contrast, under strong agitation conditions (baffled flasks) practically no aggregates were formed throughout cultivation. The method described can be used for the characterization of aggregation of other microbial cultures.
authors.affiliation: Departamento de Bioingeniería, Instituto de Biotecnología, Universidad Nacional Autónoma de México, P.O. Box 510-3, 62250, Morelos, Cuernavaca, Mexico. carlosf@ibt.unam.mx
authors.forename: Carlos
authors.initials: C
authors.lastname: Peña
authors.forename: César
authors.initials: C
authors.lastname: Reyes
authors.forename: Patricia
authors.initials: P
authors.lastname: Larralde-Corona
authors.forename: Gabriel
authors.initials: G
authors.lastname: Corkidi
authors.forename: Enrique
authors.initials: E
authors.lastname: Galindo
mesh_terms: D000693:Anaerobiosis; D016948:Azotobacter vinelandii / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D008751:Methylene Blue
chemical_list: D008751:Methylene Blue