A study of enzymic adaptation under hydrostatic pressure by moderately barotolerant bacteria that can grow at pressure up to about 500 atm revealed that some adaptive processes are relatively insensitive to pressure, whereas others are sufficiently barosensitive to compromise survival capacity in situations requiring adaptation to new substrates under pressure. Examples of the former include adaptation of Escherichia coli to arabinose catabolism for growth and adaptation of Streptococcus faecalis to catabolism of lactose, ribose, or maltose. Examples of the latter include derepression of the lac operon in Escherichia coli and induction of penicillinase synthesis by Bacillus licheniformis. For both these barosensitive systems, pressure had little effect on enzyme levels in constitutive strains or in bacteria that had previously been induced at 1 atm. Moreover, it had no detectable effect on penicillinase secretion. However, pressures of 300 to 400 atm were found to reduce markedly rates and extents of enzyme synthesis by bacteria undergoing derepression or adaptation. This inhibitory effect of pressure was reflected in greater barosensitivity with extended lag and slower growth of initially unadapted Escherichia coli cells inoculated into minimal medium with lactose as sole source of carbon and fuel, and by major reductions in the minimal inhibitory concentrations of penicillin G for unadapted B. licheniformis cells inoculated into complex, antibiotic-containing media. Cyclic adenosine 5'-monophosphate did not reverse pressure inhibition of derepression of the lac operon, and catabolite repression was complete under pressure. However, derepression of the lac operon was more sensitive to pressure at low concentrations of inducer than at high concentrations. Apparent volume changes for derepression were 94 and 60 ml/mol at inducer concentrations of about 0.5 and 5 mM, respectively. Pressure was found not to be inhibitory for uptake of beta-galactosides; in fact, it was somewhat stimulatory. Therefore, results were interpreted in terms of inducer binding and subsequent conversion of an operator-inducer-repressor complex to inactive repressor and operator. Both reactions appeared to result in an increase in volume, the former more so than the latter. We found also that 200 atm was actually stimulatory for growth of Escherichia coli in minimal media, and the bacterium was in a sense barophilic.
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机译：可以在高达500 atm的压力下生长的中等耐压性细菌在静水压力下对酶的适应性研究表明，某些适应性过程对压力相对不敏感，而其他适应性过程则对需要在适应新底物条件下适应生存能力的情况具有足够的敏感性。压力。前者的实例包括大肠杆菌对阿拉伯糖分解代谢的适应性生长和粪便链球菌对乳糖，核糖或麦芽糖分解代谢的适应性。后者的实例包括在大肠杆菌中抑制lac操纵子和通过地衣芽孢杆菌诱导青霉素酶合成。对于这两个压力敏感系统，压力对本构菌株或先前在1 atm诱导的细菌中的酶水平影响很小。而且，它对青霉素酶的分泌没有可检测的作用。然而，发现300至400atm的压力显着降低了经受去抑制或适应作用的细菌的酶合成速率和程度。压力的这种抑制作用表现为更大的压敏性，延长的滞后和最初接种的以大肠杆菌为唯一碳和燃料来源的基本培养基中未适应的大肠杆菌细胞的生长较慢，以及主要降低了对未适应的青霉素G的最低抑制浓度。地衣芽孢杆菌细胞已接种到复杂的含抗生素培养基中。环状腺苷5'-单磷酸酯没有逆转抑制lac操纵子的阻抑作用，并且在压力下完全分解代谢物阻抑。但是，在低浓度的诱导剂下，lac操纵子的抑制作用比高浓度的作用更敏感。在约0.5和5 mM的诱导剂浓度下，降压的表观体积变化分别为94和60 ml / mol。发现压力对β-半乳糖苷的摄取没有抑制作用。实际上，这有点刺激。因此，以诱导物结合以及随后将操纵基因-诱导物-阻遏物复合体转化为非活性阻遏物和操纵基因的方式解释了结果。两种反应似乎都导致体积增加，前者比后者更大。我们还发现，在基本培养基中，200 atm实际上对大肠杆菌的生长具有刺激作用，并且该细菌具有一定的嗜碱性。
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