Nonetheless, no strain had growth rates that were systematically different to that of the pooled data.
The results also showed that growth rate variability of all 16 strains is large compared to growth rate variability reported for non-spore forming cells. Studies at different water activities (a\(_w\)) suggested that the minimum water activity for growth was ~0.975. Consistent with published reports the generation time at 60 ☌ was estimated to be ~ 22 – 25 min. The studies showed that growth occurred in the temperature range 45 to ~70 ☌ with fastest growth occurring at ~60 ☌. Over 300 growth curves were generated at temperatures in the range 45 to 75 ☌, using different incubation methods, enumeration methods and growth media, although not all data sets were used because many were deemed to be unreliable due to insufficient or erratic growth of the spore-forming thermophiles under apparently well-controlled growth conditions, a phenomenon reported anecdotally by others. under time-varying temperature conditions and to identify temperatures optimal for growth and biofilm formation. The model was developed to predict the growth of Geobacillus spp. were modelled as function of temperature using a four-parameter square-root (‘Ratkowsky’) model. Growth rates of the 16 strains of Geobacillus spp. the potential to disperse biofilms on stainless steel surfaces in the flow-through reactor using exogenously provided nitric oxide (NO). growth of temperature step changes in the flow-through-system, andĤ. the kinetics of attachment, biofilm formation and eventual release of new spores from spores inoculated into the flow-through reactor system via milk and with regard to spore inoculum levels, milk flow rates and temperature ģ. originally isolated from milk powder processing plants Ģ. The effect of temperature (45 to 75 ☌), media composition and water activity (0.959 to 0.992) on growth rates of 16 Geobacillus spp. Growth studies were undertaken, and a stainless-steel, laboratory bench-scale flow-through reactor was built and used, to investigate:ġ. explore options to extend run times of dairy powder plants to develop an understanding of how these factors influence thermophile attachment and biofilm formation on stainless steel and affect the time before spore release into milk being processed into milk powder, and, based on this knowledge,Ĭ. investigate the kinetics of Geobacillus growth, biofilm development and spore formation as a function of temperature and water activity,ī. While not dangerous to human health, this potentially leads to quality defects and price reductions, requiring that the process be stopped and the plant fully cleaned.Ī. can form biofilms in dairy processing equipment that, over extended run times (e.g., >16 h), can deposit unacceptably high spore loads in end-product. Their spores can remain viable throughout the entire dairy powder industrial process, including pasteurisation (72 ☌ for 15s) and the even hotter evaporator sections. are common contaminants of milk powder processing plants. Thermophilic spore-forming bacteria such as Geobacillus spp.