Biomaterial Database

The effects of agar concentration on the growth and morphology of submerged colonies of motile and non-motile bacteria. 1997

A J Mitchell, and J W Wimpenny

School of Pure and Applied Biology, University of Wales College of Cardiff, UK.

The growth and morphology of submerged bacterial colonies was investigated. Five separate colonial forms were recognized depending both on species and on agar concentration. These were (i) branched, dendritic structures seen only with Bacillus cereus; (ii) lenticular colonies for all other species at high agar concentrations; (iii) small lobed to spherical colonies for non-motile organisms at low agar concentrations; (iv) and (v) large diffuse spherical colonies which can be further subdivided into 'snowball' or 'wispy' types for motile bacteria growing at agar concentrations below about 0.65% w/v. Viable count determinations suggested that agar concentration had little effect in the early stages of growth but that motile cells at low agar concentrations achieved higher cell numbers than did those in concentrations greater than 0.65% w/v. Transmission electron microscopy indicated that bacteria in lenticular colonies were tightly packed within lens-shaped splits in the agar whilst at low agar concentrations motile cells were well separated and appeared to move through the agar matrix.

UI	MeSH Term	Description	Entries
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D005516	Food Microbiology	The presence of bacteria, viruses, and fungi in food and food products. This term is not restricted to pathogenic organisms: the presence of various non-pathogenic bacteria and fungi in cheeses and wines, for example, is included in this concept.	Microbiology, Food
D006090	Gram-Negative Bacteria	Bacteria which lose crystal violet stain but are stained pink when treated by Gram's method.	Gram Negative Bacteria
D006094	Gram-Positive Bacteria	Bacteria which retain the crystal violet stain when treated by Gram's method.	Gram Positive Bacteria
D000362	Agar	A complex sulfated polymer of galactose units, extracted from Gelidium cartilagineum, Gracilaria confervoides, and related red algae. It is used as a gel in the preparation of solid culture media for microorganisms, as a bulk laxative, in making emulsions, and as a supporting medium for immunodiffusion and immunoelectrophoresis.
D001431	Bacteriological Techniques	Techniques used in studying bacteria.	Bacteriologic Technic,Bacteriologic Technics,Bacteriologic Techniques,Bacteriological Technique,Technic, Bacteriological,Technics, Bacteriological,Technique, Bacteriological,Techniques, Bacteriological,Bacteriologic Technique,Bacteriological Technic,Bacteriological Technics,Technic, Bacteriologic,Technics, Bacteriologic,Technique, Bacteriologic,Techniques, Bacteriologic