Inactivation combined with cell lysis of Pseudomonas putida using a low pressure carbon dioxide microbubble technology

Abstract

BACKGROUNDInactivation processes can be classified into non‐thermal inactivation methods such as ethylene oxide and γ‐radiation, and thermal methods such as autoclaving. The ability of carbon dioxide enriched microbubbles to inactivate Pseudomonas putida suspended in physiological saline, as a non‐thermal sterilisation method, was investigated in this study with many operational advantages over both traditional thermal and non‐thermal sterilisation methods.RESULTSIntroducing carbon dioxide enriched microbubbles can achieve ∼2‐Log reduction in the bacterial population after 90 min of treatment, addition of ethanol to the inactivation solution further enhanced the inactivation process to achieve 3, 2.5 and 3.5‐Log reduction for 2%, 5% and 10 %( v/v) ethanol, respectively. A range of morphological changes was observed on Pseudomonas cells after each treatment, and these changes extended from changing cell shape from rod shape to coccus shape to severe lesions and cell death. Pseudomonas putida KT 2440 was used as a model of gram‐negative bacteria.CONCLUSIONUsing CO2 enriched microbubbles technology has many advantages such as efficient energy consumption (no heat source), avoidance of toxic and corrosive reagents, and in situ treatment. In addition, many findings from this study could apply to other gram‐negative bacteria. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

On the Ability of Perfluorohexane Sulfonate (PFHxS) Bioaccumulation by Two Pseudomonas sp. Strains Isolated from PFAS-Contaminated Environmental Matrices

“…These changes may be caused by the high solvent concentration that represented a stress factor for Pseudomonas cells, as also suggested by a less electron-dense peripheral layer (indicated by black arrows), which might be caused by a loss of membrane integrity. These observations are in line with other studies where the membrane fluidity and permeability of Pseudomonas cells were compromised by excesses of ethanol [48]. Reasonably, the accumulation of lipophilic compounds between the acyl chains of the phospholipid bilayers led to the alteration of the membrane properties through a process known as narcosis [27,49], which can eventually determine swelling of the phospholipid bilayer, causing the transition towards round-shape morphology [50].…”

Ethanol addition on inactivation of Saccharomyces pastorianus by a two‐stage system with low‐pressure carbon dioxide microbubbles can accelerate the cell membrane injury

“…The inactivation efficiency of two‐stage MBCO 2 on S. pastorianus increased with increasing ethanol content in the suspension. Several similar results have been reported . In all the agars used, zero and >5 log reductions of the S. pastorianus populations in PS containing 0% and 10% ethanol, respectively, occurred by two‐stage MBCO 2 .…”

“…Several similar results have been reported. 7,14,18 In all the agars used, zero and >5 log reductions of the S. pastorianus populations in PS containing 0% and 10% ethanol, respectively, occurred by two-stage MBCO 2 . Conversely, the number of S. pastorianus cells in PS containing 5% ethanol treated with two-stage MBCO 2 was detected in YMA > YMAS > YNBA.…”

“…[8][9][10][11] Thus, it was suggested that the inactivation of Saccharomyces pastorianus, a beer yeast, by two-stage MBCO 2 might be extrapolated to be due to intracellular acidification at 408C and cell membrane injury at 458C and 508C, respectively. 9 Furthermore, it has been stated that the inactivation efficiency of pressurized CO 2 increases with increasing ethanol content, 7,14,18 although the reason is still unclear.…”

Viability of Molds and Bacteria in Tempeh Processed with Supercritical Carbon Dioxides during Storage

“…The explanation to this was that mass transfer rate of CO 2 was greater with the longer incubation period of the pressure of pressurized CO 2 . At longer incubation period the amount of CO 2 increases, accumulates into the lipophilic inner layer, and dissolves into and forms hydrogen bond with phospholipid “Mulakhudair [12]”, resulting in destruction to cell structure and function due to breakdown of lipid chains. This will further increase the permeability of cell membrane, making it easier for CO 2 to enter the cytoplasm cell.…”