Isolation and characterization of thermophilic bacteria capable of lysing microbial cells in activated sludge

• Published in: Water science and technology Vol. 54; no. 9; pp. 35 - 43
• Main Authors: Song, Yu-Dong, Hu, Hong-Ying
• Format: Journal Article
• Language: English
• Published: England IWA Publishing 01.01.2006
• Subjects: Activated sludge; Bacteria; Bacteria - cytology; Bacteria - isolation & purification; Bacteriolysis - physiology; Biodegradation, Environmental; Biological activity; Biological wastewater treatment; Composting; Composts; E coli; Environmental Microbiology; Escherichia coli - cytology; Escherichia coli - isolation & purification; High temperature; Hot Temperature; Infection Control; Low temperature; Microorganisms; Models, Biological; Sewage - microbiology; Sewage sludge; Sludge; Solubility; Thermophilic bacteria; Time Factors; Waste Management - methods; Wastewater treatment
• ISBN: 1843395843; 9781843395843
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2006.874

To find an efficient biological method to solubilize waste activated sludge (WAS) from the biological wastewater treatment process, several strains of thermophilic bacteria capable of solubilizing WAS were isolated from sewage sludge compost. The culture supernatants of the isolates were able to lyse vegetable bacterial cells and the lytic activity mainly came from the exoenzyme produced by the isolates. The culture supernatants of the different isolates showed different lysis characteristics. The factors affecting bacterial cell lysis were investigated using E. coli as a model bacterium. The E. coli cells were lysed easily at higher temperature (60 degrees C or 70 degrees C) while little lytic activity by the supernatants of isolates was observed at lower temperature (50 degrees C). The level of pH also had great influence on the lysis of E. coli cells. The E. coli cells in the early stationary growth phase were easier to lyse than those in the late stationary growth phase or death phase.