Fruiting Myxobacters as Viewed with a Scanning Electron Microscope

Abstract

Unfixed fruiting bodies of myxobacters have been viewed in great detail with a scanning electron microscope. Specimens of species of the genera Myxococcus, Chondrococcus, Archangium, Stelangium, Melittangium, Cystobacter, Polyangium, StigmatelZa, and Chondromyces were examined. The desirability of using the scanning electron microscope for the study of the gross morphology of myxobacter structures has been clearly demonstrated.The fruiting myxobacters possess a life cycle of three phases: the vegetative growth phase, in which the bacilli grow and reproduce by binary-transverse fission; the aggregative phase, in which vegetative cells in a localized area move toward a central point t o initiate the formation of a fruiting body; and last, the fruiting-body phase, a period that results in the establishment of a mature fruiting body. The fruiting body contains or bears the resting cells, microcysts, or myxospores and has a morphology that is typical for the given species. Myxobacters are usually identified by the form and structure of the mature fruiting body. In the past the gross morphology of fruiting bodies has been illustrated primarily by three techniques: a brief chronological listing of these includes line drawings by Thaxter (9), lithographs by Jahn (2), and photomicrographs obtained by compound microscopy (McCurdy Scanning electron microscopy has only recently been employed in the study of myxobacter fruiting bodies. I. L. Roth (Bacteriol. Proc., p. 21, 1971) (7) reported the observation of a number of myxobacters by scanning electron microscopy. The present scanning electron microscopy study (presented in part at the 72nd Annual Meeting of the American Society for Microbiology, Philadelphia, Pa., April 1972) was undertaken to expand on the documentation of the fine detail of the fruiting bodies of myxobacters. MATERIALS AND METHODSMyxobactez specimens. The specimens of fruiting myxobacters were obtained from the herbarium collection of one of us (E.R.B.). The fruiting bodies were on various substrates, either bark, rabbit pellets, filter paper, or membrane filter, and most were at least 10 years old. All of the isolates were identified according to Bergey's Manual (1) and the studies of McCurdy (4-6). The Myxococcus fulvus specimen was from a rabbit pellet culture isolated from South Carolina soil. The Myxococcus xanthus and Chondromyces crocatus specimens were also from rabbit pellet cultures, and both had been isolated from soil collected in Missouri. The specimen of Myxococcus stipitatus, isolated from a Michigan stream, was on a membrane filter. Chondrococcus coralloides no. 1 and the Cystobacter fuscus specimen were from rabbit pellet cultures isolated from St. John, U.S.V.I. soil. C. coralloides no. 2 and the Archangium primigenium and Melittangium lichenicolum specimens were from Ulmus americana bark collected in Missouri. The specimen of Stelangium muscorum was from Juglans nigra bark collected in Missouri. The Polyangiurn vitellinum and Stigmatella aurantiaca specimens were both from Lirioden...

Fruiting body morphogenesis in submerged cultures of Myxococcus xanthus

“…It resembles in this respect the developmental process on an air-exposed surface of agar (23,24). The morphology of submerged fruiting bodies resembles those on agar (2,4,15,16,18). Evidently the developmental process is not disturbed by an overlying layer of free liquid.…”

Ultrastructure of Polyangium cellulosum

“…Previous studies (4,9,14) have used air-dried specimens; air drying seems to cause stress upon, at least, the fruiting-body structures, and perhaps demonstration of the slime protrusions from vegetative cells.…”

“…More recently, scanning electron microscopy (SEM) studies (4,9,14) have shown some details of the exterior of individual cells and fruiting bodies. Each of the studies has contributed to our relatively meager knowledge of the fine structure of fruiting myxobacteria.…”

Polysaccharides Produced by Cystobactev, Archangium, Sorangium and Stigmatella Species

“…As demonstrated in the elegant studies of Reichenbach (cited in Gerth & Reichenbach, 1978), the process of fructification arises through cooperative morphogenesis. Large numbers of vegetative bacteria converge to form aggregates which differentiate into the fruiting bodies of varying complexity (Reichenbach & Dworkin, 1969;Brockman & Todd, 1974;Grilione & Pangborn, 1975).…”