Exospore
An exospore or ectospore is a special form of spores , a means for the reproduction of bacteria or fungi . They arise from terminal constriction of daughter cells ( budding ) and, in contrast to endospores, do not have a spore envelope. When it comes to thick-walled, spherical structures that arise from the elongated, vegetative bacterial cell, one speaks of cysts . Both exospores and cysts are permanent forms in individual types of bacteria.
Due to their almost completely stopped metabolism and their low water content, the exospores are more resistant to dehydration, heat, radiation and chemical stress than the vegetative cell. This applies only to a limited extent to cysts as they are not heat-resistant.
One exospore generator is, for example, the methane- utilizing bacterial genus Methylosinus , while cysts can occur in the bacterial genera Azotobacter and Methylocystis .
Individual evidence
- ↑ a b c Hans G. Schlegel: General microbiology. 7th edition. Thieme Verlag, Stuttgart / New York 1992, ISBN 3-13-444607-3