Effect of desiccation on envelopes of the cyanobacterium chroococcidiopsis sp. (chroococcales)

Abstract

Chroococcidiopsis sp. cells present hypolithically in quartz flints collected in the Negev Desert (Israel) and in wet and desiccated laboratory cultures were examined by light and transmission electron microscopy. The composition of Chroococcidiopsis cell envelopes was characterized by cytochemical tests for detection of sporopollenin-like compounds, and acid, sulphated and beta-linked polysaccharides, positively charged glycoproteins, lipids and proteins. These compounds were present as very elaborate structures in the envelope of cells from stones and in desiccated cultures. An increased envelope thickness is probably useful in the prevention of water loss, although it could cause cell death by reducing exchange with the environment. Isolated living cells that occurred in desiccated cultures might be regarded as resting forms allowing the survival of the cyanobacterium. © 1996 The British Phycological Society.