Rokem J S, Goldberg I, Mateles R I
Biotechnol Bioeng. 1978 Oct;20(10):1557-64. doi: 10.1002/bit.260201005.
The maintenance coefficient, ms (mmol substrate/g cell dry wt hr), of two distinct groups of C1-utilizing bacteria has been determined by growing the organisms in an aerobic continuous culture limited by different C1 growth substrates. For growth on methanol, ms = 2.5 +/- 0.3 for Pseudomonas C; 3.9 +/- 0.7 for Ps. methylotropha (these bacteria utilize methanol via the ribulose monophosphate pathway of formaldehyde fixation); 1.5 +/- 0.2 for Pseudomonas 1, and 2.3 +/- 0.4 for Pseudomonas 135 (the latter bacteria utilize C1-compounds via the serine pathway). For growth on formaldehyde, ms = 1.5 +/- 0.3 for Pseudomonas 1 and 2.7 +/- 0.7 for Pseudomonas 135, whereas on formate the values for ms are 1.0 +/- 0.2 and 4.4 +/- 1.3; respectively. Although the maintenance coefficients did not differ systematically between the two groups of bacteria, the maintenance requirements per generation of the serine pathway bacteria were considerably higher (8.7 vs. 3.9) owing to their slower growth rate. The maximum molar yield values, YMmax (g cell dry wt/mol substrate utilized), corrected for the maintenance energy of bacteria which utilize C1-compounds via the ribulose monophosphate pathway averaged 19.1 when grown on methanol, while the values for bacteria which use the serine pathway averaged 13.5. On formaldehyde an average value of 11.5 is obtained and on formate the average value was 7.4 in the serine pathway bacteria.
通过在受不同C1生长底物限制的好氧连续培养中培养微生物，测定了两组不同的利用C1细菌的维持系数ms（mmol底物/克细胞干重·小时）。对于以甲醇为生长底物的情况，假单胞菌C的ms = 2.5±0.3；甲基营养假单胞菌的ms = 3.9±0.7（这些细菌通过甲醛固定的磷酸戊糖途径利用甲醇）；假单胞菌1的ms = 1.5±0.2，假单胞菌135的ms = 2.3±0.4（后一种细菌通过丝氨酸途径利用C1化合物）。对于以甲醛为生长底物的情况，假单胞菌1的ms = 1.5±0.3，假单胞菌135的ms = 2.7±0.7；而对于以甲酸为生长底物的情况，ms值分别为1.0±0.2和4.4±1.3。虽然两组细菌的维持系数没有系统性差异，但由于丝氨酸途径细菌的生长速度较慢，其每代的维持需求要高得多（8.7对3.9）。通过磷酸戊糖途径利用C1化合物的细菌，校正其维持能量后的最大摩尔产率值YMmax（克细胞干重/利用的底物摩尔数），在以甲醇为生长底物时平均为19.1，而使用丝氨酸途径的细菌的该值平均为13.5。在丝氨酸途径细菌中，以甲醛为生长底物时平均得到的值为11.5，以甲酸为生长底物时平均为7.4。
