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Microbial Cell Structure and Function
How Bacteria Survive with Endospores
Description
Endospores help some bacteria survive harsh conditions. These dormant cells are made mainly by Gram-positive bacteria such as Bacillus and Clostridium. They are highly resistant to heat, ultraviolet and ionizing radiation, drying, and toxic chemicals. In rare cases, endospore-like structures have also been seen in some Gram-...
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Transcript
芽孢是处于休眠状态且具有高度抗性的细胞,通常由革兰氏阳性细菌在不利环境(如极端高温、辐射、极度干燥或存在强效化学物质)下形成,以维持其存活。
芽孢形成,即孢子形成,由环境胁迫或营养耗竭所触发。
它始于DNA复制,随后是不对称细胞分裂,将前孢子与母细胞分离开来。
前孢子含有染色体、细胞质成分以及大量钙-吡啶二羧酸复合物。
该复合物负责芽孢的脱水,以及稳定和保护其 DNA 免受热损伤。
随后,母细胞吞噬前孢子,在其周围形成双层膜结构。
接着,在两层膜之间形成一层较厚的肽聚糖层——即皮层。
在皮层周围会形成一层保护性蛋白质外壳,从而增强芽孢在极端条件下的抗逆性。
母细胞裂解,将成熟的孢子释放到环境...
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