The enzyme activity-activating effects of heavy metals could
result from that Cu acted as a coenzyme or cofactor, thereby enhancing enzyme activity (Kim et al., 2010), or Cu stimulated mi-crobes growth or multiplication, thus increasing enzyme synthesis
and secretion of microbes, or under Cu stresses, Cu-tolerant mi-crobes formed dominant populations through their succession
and as a result enzyme synthesis and secretion got promoted.
Meanwhile, there are many reasons that can explain the enzyme
inhibition of heavy metals.