Lysis of stationary-phase bacterial cells by synergistic action of lytic peptidase and glycosidase from thermophiles

Lysis of bacterial cells is considered a key step in biological treatment process of waste activated sludge. Most cells in waste activated sludge are long-cultured cells in stationary- or death-phases, which are proved more difficult to be lysed than actively-growing cells. However, few attentions have been paid to the lysis of long-cultured cells. In this study, synergistic action of different lytic enzymes from two thermophilic bacteria, Geobacillus spp. SY9 and SY14, were discovered to promote the lysis of long-cultured cells. The combinational action of the lytic enzymes from the two thermophilic bacteria were significantly better than their individual action and the cell lysis rates at the optimized combinational ratio were higher than that of their individual action by 2–3 times. The results of selective inhibition test infer that the potential lytic enzymes of SY9 and SY14 are glycosidase and peptidase, respectively. Hence, the combinational action of different lytic enzymes is a potential measure to promote the lysis of long-cultured cells.