Synergistic Effects of Nisin, Lysozyme, Lactic Acid, and Citricidal^TM for Enhancing Pressure-Based Inactivation of <i>Bacillus amyloliquefaciens</i>, <i>Geobacillus stearothermophilus</i>, and <i>Bacillus atrophaeus</i> Endospores

• Main Authors: Sadiye Aras, Niamul Kabir, Sabrina Wadood, Jyothi George, Shahid Chowdhury, Aliyar Cyrus Fouladkhah
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Microorganisms
• Subjects: high-pressure processing; bacterial endospores; bioactive compounds
• Online Access: https://www.mdpi.com/2076-2607/9/3/653

The inactivation of bacterial endospores continues to be the main curtailment for further adoption of high-pressure processing in intrastate, interstate, and global food commerce. The current study investigated the effects of elevated hydrostatic pressure for the inactivation of endospore suspension of three indicator spore-forming bacteria of concern to the food industry. Additionally, the effects of four bacteriocin/bactericidal compounds were studied for augmenting the decontamination efficacy of the treatment. Elevated hydrostatic pressure at 650 MPa and at 50 °C was applied for 0 min (untreated control) and for 3, 7, and 11 min with and without 50K IU of nisin, 224 mg/L lysozyme, 1% lactic acid, and 1% Citricidal^TM. The results were statistically analyzed using Tukey- and Dunnett’s-adjusted ANOVA. Under the condition of our experiments, we observed that a well-designed pressure treatment synergized with mild heat and bacteriocin/bactericidal compounds could reduce up to >4 logs CFU/mL (i.e., >99.99%) of bacterial endospores. Additions of nisin and lysozyme were able, to a great extent, to augment (<i>p</i> < 0.05) the decontamination efficacy of pressure-based treatments against <i>Bacillus amyloliquefaciens</i> and <i>Bacillus atrophaeus</i>, while exhibiting no added benefit (<i>p</i> ≥ 0.05) for reducing endospores of <i>Geobacillus stearothermophilus</i>. The addition of lactic acid, however, was efficacious for augmenting the pressure-based reduction of bacterial endospores of the three microorganisms.