McIntire W S, Weyler W
Molecular Biology Division, Veterans Administration Medical Center, San Francisco, California 94121.
Appl Environ Microbiol. 1987 Sep;53(9):2183-8. doi: 10.1128/aem.53.9.2183-2188.1987.
Two variants of the methylotrophic bacterium W3A1, designated W3A1-S (slimy) and W3A1-NS (nonslimy), were compared with respect to their ability to grow in batch culture on the C1 substrates methylamine, methanol, and trimethylamine. Substrate utilization, cell density, pH, cellular and soluble polysaccharide production, and concentrations of the enzymes methylamine dehydrogenase, trimethylamine dehydrogenase, and methanol dehydrogenase produced were measured as a function of growth. The ability of the two bacterial variants to excrete the redox cofactor pyrroloquinoline quinone into the growth medium was also investigated. The two variants were similar with respect to all properties measured, except that W3A1-S produced significantly more capsular polysaccharides than variant W3A1-NS. Pyrroloquinoline quinone was excreted when either variant was grown on any of the C1 substrates investigated but was maximally produced when the methylamine concentration was 0.45% (wt/vol). This cofactor is excreted only as bacterial growth enters the stationary phase, a time when the levels of trimethylamine dehydrogenase and the quinoproteins methanol dehydrogenase and methylamine dehydrogenase begin to decline. It is not known whether the pyrroloquinoline quinone found in the medium is made de novo for excretion, derived from the quinoprotein pool, or both. Pyrroloquinoline quinone excretion has been observed with other methylotrophs, but this is the first instance where the excretion was observed with substrates other than methanol.
对甲基营养型细菌W3A1的两个变体，即W3A1-S（黏液型）和W3A1-NS（非黏液型），就其在分批培养中利用一碳底物甲胺、甲醇和三甲胺生长的能力进行了比较。测定了底物利用情况、细胞密度、pH值、细胞和可溶性多糖的产生，以及所产生的甲胺脱氢酶、三甲胺脱氢酶和甲醇脱氢酶的浓度随生长的变化情况。还研究了这两种细菌变体向生长培养基中分泌氧化还原辅因子吡咯喹啉醌的能力。除了W3A1-S产生的荚膜多糖比变体W3A1-NS显著更多外，这两个变体在所有测定的特性方面都相似。当任何一个变体在任何一种所研究的一碳底物上生长时都会分泌吡咯喹啉醌，但当甲胺浓度为0.45%（重量/体积）时产量最高。这种辅因子仅在细菌生长进入稳定期时分泌，此时三甲胺脱氢酶以及醌蛋白甲醇脱氢酶和甲胺脱氢酶的水平开始下降。尚不清楚培养基中发现的吡咯喹啉醌是为了分泌而重新合成的，是源自醌蛋白库，还是两者皆有。在其他甲基营养菌中也观察到了吡咯喹啉醌的分泌，但这是首次在除甲醇以外的底物上观察到这种分泌现象。
