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Effect of NaOH (caustic wash) on the viability, surface characteristics and adhesion of spores of a Geobacillus sp. isolated from a milk powder production line
Author(s) -
Brent Seale R.,
Flint S.H.,
James McQuillan A.,
Bremer P.J.
Publication year - 2011
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.2010.02970.x
Subject(s) - spore , microbiology and biotechnology , adhesion , geobacillus stearothermophilus , bacteria , food science , caustic (mathematics) , chemistry , biology , thermophile , physics , organic chemistry , genetics , mathematical physics
Aim: To investigate the viability, surface characteristics and ability of spores of a Geobacillus sp. isolated from a milk powder production line to adhere to stainless steel surfaces before and after a caustic (NaOH) wash used in clean‐in‐place regimes. Methods and Results: Exposing sessile spores to 1% NaOH at 65°C for 30 min decreased spore viability by two orders of magnitude. The zeta potential of the caustic treated spores decreased from −20 to −32 mV and they became more hydrophobic. Transmission electron microscopy revealed that caustic treated spores contained breaks in their spore coat. Under flow conditions, caustic treated spores suspended in 0·1 mol l −1 KCl were shown to attach to stainless steel in significantly greater numbers (4·6 log 10 CFU cm −2 ) than untreated spores (3·6 log 10 CFU cm −2 ). Conclusions: This research suggests that spores surviving a caustic wash will have a greater propensity to attach to stainless steel surfaces. Significance of Study: The practice of recycling caustic wash solutions may increase the risk of contaminating dairy processing surfaces with spores.