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大肠杆菌生长极为缓慢。

Very slow growth of Escherichia coli.

作者信息

Chesbro W, Evans T, Eifert R

出版信息

J Bacteriol. 1979 Aug;139(2):625-38. doi: 10.1128/jb.139.2.625-638.1979.

Abstract

A recycling fermentor (a chemostat with 100% biomass feedback) was used to study glucose-limited behavior of Escherichia coli B. The expectation from mass transfer analysis that growth would asymptotically approach a limit mass determined by the glucose provision rate (GPR) and the culture's maintenance requirement was not met. Instead, growth proceeded at progressively lower rates through three distinct phases. After the fermentor was seeded, but before glucose became limiting, growth followed the usual, exponential path (phase 1). About 12 h postseeding, residual glucose in the fermentor fell below 1 microgram . ml-1 and the growth rate (dx/dt) became constant and a linear function of GPR (phase 2). The specific growth rate, mu, therefore fell continuously throughout the phase. Biomass yield and glucose assimilation (13%) were near the level for exponential growth, however, and independent of GPR over a broad range. At a critical specific growth rate (0.04 h-1 for this strain), phase 2 ended abruptly and phase 3 commenced. In phase 3, the growth rate was again constant, although lower than in phase 2, so that mu continued to fall, but growth rates and yields were praboloid functions of GPR. They were never zero, however, at any positive value of GPR. By inference, the fraction of metabolic energy used for maintenance functions is constant for a given GPR, although different for phases 2 and 3, and independent of biomass. In both phases 2 and 3, orcinol, diphenylamine, and Lowry reactive materials were secreted at near-constant rates such that over 50% as much biosynthetic mass was secreted as was retained by the cells.

摘要

使用循环发酵罐(一种具有100%生物量反馈的恒化器)来研究大肠杆菌B在葡萄糖受限条件下的行为。传质分析预期生长将渐近地接近由葡萄糖供应速率(GPR)和培养物的维持需求所确定的极限质量,但这一预期并未实现。相反,生长通过三个不同阶段以逐渐降低的速率进行。在向发酵罐接种后,但在葡萄糖成为限制因素之前,生长遵循通常的指数路径(阶段1)。接种后约12小时,发酵罐中的残余葡萄糖降至1微克·毫升-1以下,生长速率(dx/dt)变得恒定,并且是GPR的线性函数(阶段2)。因此,比生长速率μ在整个阶段持续下降。然而,生物量产量和葡萄糖同化率(13%)接近指数生长水平,并且在很宽的范围内与GPR无关。在一个临界比生长速率(该菌株为0.04 h-1)时,阶段2突然结束,阶段3开始。在阶段3中,生长速率再次恒定,尽管低于阶段2,因此μ继续下降,但生长速率和产量是GPR的抛物线函数。然而,在任何正的GPR值下,它们都不会为零。由此推断,对于给定的GPR,用于维持功能的代谢能量比例是恒定的,尽管在阶段2和3中有所不同,并且与生物量无关。在阶段2和3中,苔黑酚、二苯胺和洛瑞反应性物质均以近乎恒定的速率分泌,以至于分泌的生物合成物质比细胞保留的物质多50%以上。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/f71f/216912/0a238daa07fb/jbacter00279-0317-a.jpg

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