title: Study of the influence of sporulation conditions on heat resistance of Geobacillus stearothermophilus used in the development of biological indicators for steam sterilization.
abstract: Biological indicators are important tools in infection control via sterilization process monitoring. The use of a standardized spore crop with a well-defined heat resistance will guarantee the quality of a biological indicator. Ambient factors during sporulation can affect spore characteristics and properties, including heat resistance. The aim of this study is to evaluate the main sporulation factors responsible for heat resistance in Geobacillus stearothermophilus, a useful biological indicator for steam sterilization. A sequence of a three-step optimization of variables (initial pH, nutrient concentration, tryptone, peptone, beef extract, yeast extract, manganese sulfate, magnesium sulfate, calcium chloride and potassium phosphate) was carried out to screen those that have a significant influence on heat resistance of produced spores. The variable exerting greatest influence on G. stearothermophilus heat resistance during sporulation was found to be the initial pH. Lower nutrient concentration and alkaline pH around 8.5 tended to enhance decimal reduction time at 121 °C (D(121°C)). A central composite design enabled a fourfold enhancement in heat resistance, and the model obtained accurately describes positive pH and negative manganese sulfate concentration influence on spore heat resistance.
authors.affiliation: Bioprocess Engineering and Biotechnology Department, Federal University of Paraná, Paraná, Brazil. belquis_@hotmail.com
authors.forename: Belquis P
authors.initials: BP
authors.lastname: Guizelini
authors.forename: Luciana P S
authors.initials: LP
authors.lastname: Vandenberghe
authors.forename: Sandra Regina B R
authors.initials: SR
authors.lastname: Sella
authors.forename: Carlos Ricardo
authors.initials: CR
authors.lastname: Soccol
mesh_terms: D001411:Geobacillus stearothermophilus / Q000502:physiology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D013171:Spores, Bacterial / Q000502:physiology*; D013227:Steam; D013242:Sterilization
chemical_list: D007202:Indicators and Reagents; D013227:Steam