Williams Jonathan, Trautwein-Schult Anke, Kunze Gotthard, Baronian Kim
School of Biological Sciences, University of Canterbury, Private Bag, Christchurch, 4800, New Zealand.
Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Gatersleben, Germany.
Appl Microbiol Biotechnol. 2017 Jun;101(11):4725-4736. doi: 10.1007/s00253-017-8199-3. Epub 2017 Mar 15.
The yeast Arxula adeninivorans has previously been shown to naturally secrete the redox molecule uric acid (UA). This property suggested that A. adeninivorans may be capable of functioning as the catalyst for a mediator-less yeast-based microbial fuel cell (MFC) if the level of UA it secretes could be increased. We investigated the effects of a number of parameters on the level of UA produced by A. adeninivorans. The concentration of UA accumulated in a dense cell suspension of A. adeninivorans after 20 h incubation was shown to be significantly lower in aerated suspensions compared with that in anaerobic conditions due to UA being rapidly oxidised by dissolved oxygen. The presence of carbon sources, glucose and glycerol, both caused a reduction in UA production compared with that in starvation conditions. The transgenic A. adeninivorans strain, G1221 (auox), showed higher UA production at 37 °C, but at 47 °C, the wild-type LS3 accumulated higher concentrations; however, elevated temperatures also resulted in very high cell mortality rates. An initial buffer pH of 8 caused a higher concentration of UA to accumulate, but high pH is detrimental to cell metabolism and the cells actively work to lower the pH of their environment. It appears that most parameters which increase the amount of UA produced by A. adeninivorans have concomitant disadvantages for cell metabolism, and as such, its potential as a self-mediating MFC catalyst seems doubtful.
先前已证明酵母嗜腺嘌呤阿苏菌能天然分泌氧化还原分子尿酸（UA）。这一特性表明，如果嗜腺嘌呤阿苏菌分泌的UA水平能够提高，那么它可能有能力作为无介质酵母基微生物燃料电池（MFC）的催化剂。我们研究了多个参数对嗜腺嘌呤阿苏菌产生UA水平的影响。结果表明，由于UA被溶解氧快速氧化，在通气悬浮液中培养20小时后，嗜腺嘌呤阿苏菌致密细胞悬浮液中积累的UA浓度显著低于厌氧条件下的浓度。与饥饿条件相比，碳源葡萄糖和甘油的存在均导致UA产量降低。转基因嗜腺嘌呤阿苏菌菌株G1221（auox）在37℃时显示出较高的UA产量，但在47℃时，野生型LS3积累的浓度更高；然而，温度升高也导致细胞死亡率非常高。初始缓冲液pH值为8时会积累更高浓度的UA，但高pH值对细胞代谢有害，细胞会主动降低其环境的pH值。看来，大多数能增加嗜腺嘌呤阿苏菌产生UA量的参数对细胞代谢都有相应的不利影响，因此，它作为自介导MFC催化剂的潜力似乎令人怀疑。
