O'Connor K, Duetz W, Wind B, Dobson A D
Microbiology Department, University College, Cork, Ireland.
Appl Environ Microbiol. 1996 Oct;62(10):3594-9. doi: 10.1128/aem.62.10.3594-3599.1996.
Styrene degradation in Pseudomonas putida CA-3 has previously been shown to be subject to catabolite repression in batch culture. We report here on the catabolite-repressing effects of succinate and glutamate and the effects of a limiting inorganic-nutrient concentration on the styrene degradation pathway of P. putida CA-3 in a chemostat culture at low growth rates (0.05 h-1). Oxidation of styrene and the presence of styrene oxide isomerase and phenylacetaldehyde dehydrogenase activities were used as a measure of the expression of the styrene degradation pathway. Both glutamate and succinate failed to repress the styrene degradation ability under growth conditions of carbon and energy limitation. Lower levels of enzyme activities of the styrene degradation pathway were seen in cells grown on styrene or phenylacetic acid (PAA) under conditions of both ammonia and sulfate limitation than were seen under carbon and energy limitation. Cells grown on PAA under continuous culture oxidize styrene and styrene oxide and possess styrene oxide isomerase and NAD(+)-dependent phenylacetaldehyde dehydrogenase activities. Catabolite repression of styrene metabolism was observed in cells grown on styrene or PAA in the presence of growth-saturating (nonlimiting) concentrations of succinate or glutamate under sulfate limitation.
先前已表明，恶臭假单胞菌CA-3中苯乙烯的降解在分批培养中会受到分解代谢物阻遏。我们在此报告琥珀酸和谷氨酸的分解代谢物阻遏作用，以及在恒化器培养中低生长速率（0.05 h-1）下，无机营养物浓度限制对恶臭假单胞菌CA-3苯乙烯降解途径的影响。苯乙烯的氧化以及环氧苯乙烯异构酶和苯乙醛脱氢酶活性的存在被用作苯乙烯降解途径表达的衡量指标。在碳和能量限制的生长条件下，谷氨酸和琥珀酸均未能抑制苯乙烯的降解能力。在氨和硫酸盐限制条件下，在以苯乙烯或苯乙酸（PAA）为碳源生长的细胞中，苯乙烯降解途径的酶活性水平低于在碳和能量限制条件下的水平。在连续培养中以PAA为碳源生长的细胞能够氧化苯乙烯和环氧苯乙烯，并具有环氧苯乙烯异构酶和NAD(+)-依赖性苯乙醛脱氢酶活性。在硫酸盐限制下，当存在生长饱和（非限制）浓度的琥珀酸或谷氨酸时，在以苯乙烯或PAA为碳源生长的细胞中观察到苯乙烯代谢的分解代谢物阻遏现象。
