静电作用和疏水作用对黑曲霉孢子凝聚的影响

Combination effects of zeta potential and hydrophobicity on Aspergillus niger spore aggregation

真菌孢子的凝聚对真菌菌丝球的形成有重要作用,也影响真菌产物的产量。黑曲霉是一种生产多种代谢产物的重要工业微生物。本文以黑曲霉孢子为研究对象,通过磷酸缓冲液处理和溶胀手段改变孢子之间的静电作用和疏水作用,探究了静电作用和疏水作用对黑曲霉孢子凝聚的影响。用磷酸缓冲液处理孢子,去除孢子外层的部分黑色素,减少了孢子的羧基基团以及疏水蛋白,导致孢子间的凝聚增加。孢子的溶胀过程破坏了孢子最外部的疏水蛋白层,减少了孢子间的疏水作用,并使Zeta电位上升,增加孢子的负电荷,使得孢子聚集减少。而未处理的孢子一直展现出较强的凝聚,没有随着pH的升高而显示出显著差异。溶胀孢子的凝聚颗粒随着p H升高而明显变小,表明疏水性降低和电荷的增加导致孢子间凝聚程度减弱,且疏水作用对孢子凝聚的影响大于静电作用。本研究为真菌液态深层发酵过程中菌丝球的形成提供了理论依据。

Fungal spore aggregation plays an important role in the formation of fungal pellet, which influences fungal metabolites production. Aspergillus niger is one of the important industrial microorganisms for many metabolites production. The electrostatic interaction and hydrophobicity are two driving forces of spore aggregation. In this research, these two forces of fungal spore aggregation by phosphate buffer treatment and swelling using Aspergillus niger as a model strain were investigated. Melanin extraction decreased the carboxyl groups and hydrophobin rodlet of the spores. The swelling process decreased hydrophobicity and increased the zeta potential of spores, leading electrostatic interaction. When the zeta potential decreases, the aggregates＇ size of the spores would to a changing of the decrease, and the size of spores aggregates decreased with the decreasing hydrophobicity of spores. The fungal spore aggregation was the result of combination of electrostatic interaction and hydrophobicity, changed during the swelling process. These results provided a base for investigation of fungal pellet formation from the view of spore aggregation.