CHAPTER 10 BACTERIAL REPRODUCTION AND GROWTH OF MICROORGANISMS

a duplicate genome. In the case of the actinomycetes, such as Streptomyces, reproduction involves the formation of hyphae. In this mode of reproduction the cell elongates, forming a relatively long and generally branched filament, or hypha.Regardless of the mode of reproduction, bacterial multiplication requires replication of the bacterial chromosome and synthesis of new boundary layers, including cell wall and plasma membrane structures. All these modes of reproduction are asexual, like binary fission.

Bacterial Spore Formation

Sporesare specialized cells produced by some bacteria that are involved in survival or reproduction. The production of spores represents an interesting deviation from vegetative cell reproduction. Some types of spores, including endospores(heat resistant spores formed within the cell) and cysts(resting or dormant cells sometimes enclosed in a sheath) are not repro-

ductive structures and their production does not i crease the number of living cells. In contra arthrospores(spores formed by the fragmentation hyphae) are produced by different bacteria as part their reproductive cycles. The fragmentation of h phae to produce arthrospores forms numerous pro eny cells. Additionally, myxobacteria form reprodutive structures, called fruiting bodies, within whi numerous spores, called myxospores(resting cells the myxobacteria formed within a fruiting body), a formed. Myxospores are the progeny that result fro reproduction of myxobacteria; they are able to si vive transport through the air and increase the si vival capacity of myxobacteria by permitting disser ination to areas with adequate supplies of nutrien to support bacterial growth and reproduction.

Spores are specialized resistant resting cells pro­duced by bacteria. Endospores are involved in survival, but other types of spores, such as arthrospores, are involved with reproduction.

Date: 2015-02-28; view: 2457