Magnesium capability to attenuate the toxicity of aluminum on the growth of Saccharomyces cerevisiae PE-2

Summary The magnesium (Mg) capability to attenuate the toxicity of aluminum (Al) for the trehalose content, anaerobic growth, viability and budding rate of Saccharomyces cerevisiae, was studied in this work. Fermentations were carried out in triplicate with sterilized and diluted sugar cane media (4% total reducing sugars/pH 4.0) containing different Al (0.0, 50, 100 and 150 mg L-1) and Mg (0.0, 50 and 100 mg L-1) concentrations. The media were inoculated with 1 mL of 1% (wet basis) yeast suspension and incubated at 30ºC, 70 rpm for 20 hours in orbital shaker. At specific times during fermentation portions of cell suspension were taken out and the biomass concentration, yeast viability, budding rate and trehalose content on cells determined. The increase of Al levels, from 0.0 up to 150 mg L-1, showed a reduction on the yeast growth of approximately 95%, 55% and 18% as Mg increased from 0.0 to 50 and 100 mg L-1, respectively. The trehalose content experienced its lowest reduction when greater amounts of Mg were added to the fermentation process. Cell viability showed greater reductions as the content of Al in the media increased. Magnesium effectively protected yeast cells against the deleterious effects of Al on cell growth, viability, budding and trehalose content.

研究摘要：本研究探究了镁（Mg）对铝（Al）介导的酿酒酵母（Saccharomyces cerevisiae）海藻糖含量、厌氧生长、细胞活力及出芽率毒性的缓解作用。实验采用经灭菌处理的稀释甘蔗培养基（总还原糖浓度为4%、pH 4.0），设置不同浓度梯度的Al与Mg组合（Al浓度为0.0、50、100、150 mg·L⁻¹，Mg浓度为0.0、50、100 mg·L⁻¹），每组实验均进行三次平行重复发酵。向培养基中接种1 mL浓度为1%（湿基）的酵母悬浮液，于30℃、70 rpm条件下在轨道摇床中培养20小时。在发酵过程的特定时间点采集部分细胞悬浮液样本，分别测定菌体浓度、酵母细胞活力、出芽率及胞内海藻糖含量。当Al浓度从0.0提升至150 mg·L⁻¹时，随着Mg浓度分别从0.0升至50、100 mg·L⁻¹，酵母生长抑制率分别达到约95%、55%和18%。向发酵体系中添加更高浓度的Mg时，胞内海藻糖含量的降幅降至最低。培养基中Al浓度升高会显著降低酵母细胞活力。综上，镁可有效保护酿酒酵母细胞免受铝对其生长、活力、出芽过程及胞内海藻糖含量的有害影响。