Temperature dependence of Bacillus cereus spores: effects on sporulation, germination behavior, and inner membrane protein responses.

The effect of combined stress factors on resistant Bacillus cereus spores in sauerkraut production

Sauerkraut is traditionally prepared by shredding cabbage, salting it, and allowing facultative fermentation to occur at room temperature. However, improper hygiene practices during handling can still introduce Bacillus cereus spores, a potential foodborne pathogen, into the sauerkraut. This study investigated the effectiveness of a combination of stress factors (lactic acid, NaCl, and temperature) on B. cereus spores. The findings indicated that all three factors significantly affected spore germination rate, membrane permeability, fluidity, and the release of dipicolinic acid (DPA) and DNA. A mathematical model was established to predict stress responses based on the combined effects of these factors. The optimal conditions for controlling B. cereus spore outgrowth were identified as 2% NaCl, 1.2% lactic acid, and heat treatment at 82°C for 20 min. This combination effectively disrupted B. cereus spores and could be used as a control point during sauerkraut fermentation. Verification through a sauerkraut production model with a B. cereus spores challenge test demonstrated the efficacy of this approach, with significant reductions in B. cereus spores to approximately 1 log cycle during fermentation. This study highlights the potential of combining multiple stress factors to control B. cereus spores in pickled and fermented fruit and vegetable products.

Mechanism of Thermosonication in Inhibiting Spore of Heat-Resistant Bacillus subtilis via Metabolic Networks and Gene Regulation

This study systematically elucidates the dual inhibitory mechanisms of thermosonication against Bacillus subtilis spores through integrated transcriptomic-proteomic analysis, identifying critical genes at the regulatory level and clarifying indirect suppression through metabolic network disruption.

Sporicidal activity mechanism of lactic acid and peracetic acid on bovine pathogenic Bacillus cereus spores

In recent years, the pathogenicity of Bacillus cereus (B. cereus) has increased significantly, its host adaptability has continued to expand, and the infection spectrum has also expanded. At the same time, food contamination by B. cereus is also common. Therefore, it is of practical significance to select green, safe and effective inhibitors. Lactic acid (LA) and peroxyacetic acid (PAA) possess good antibacterial properties, making them environmentally friendly, safe, and non-toxic. The purpose of this experiment was to preliminarily explore the inhibition mechanism of LA and PAA on B. cereus spores. The effects of LA and PAA on B. cereus spores were evaluated by measuring the MIC and MBC of LA and PAA inhibiting B. cereus spores, the effect of spore germination, the turbidity of spore suspension (OD600), the release of macromolecules in spores, the content of ROS in spores, the release of DPA in spores and the hydrophobicity of spore surface. The results showed that the MIC and MBC of LA against spores were 0.315% and 40.375%, respectively, and the MIC and MBC of PAA against spores were 0.030% and 0.119%, respectively. Different concentrations of LA and PAA could decrease the spore germination rate, spore suspension turbidity, and spore hydrophobicity of B. cereus, and also increase the release of macromolecules in B. cereus spores, the content of spore reactive oxygen species (ROS), and the release of spore dipicolinic acid (2,6-pyridinedicarboxylic acid, DPA). The above results showed that LA and PAA could inactivate B. cereus spores by damaging the integrity of the cell membrane and cell wall of spores.

Seeing beyond the wall: biochemical composition and morphology of spores as indicators of reproductive potential of lycophytes

Low Temperature Plasma Impairs the Pathogenicity of Alternaria sp. by Disrupting Its Cell Membrane and Redox Homeostasis

Alternaria sp. is a major pathogen causing postharvest storage decay of European plum. This study evaluated the antifungal activity of low-temperature plasma (LTP) against Alternaria sp. and elucidated its mechanism. With increasing LTP exposure, both mycelial growth and spore germination of Alternaria sp. were progressively inhibited; at 70 kV for 40 s, inhibition reached 100% and 99.32 ± 0.59%, respectively. Ultrastructural observations revealed abnormal spore morphology (swelling and shrinkage). Fluorescence microscopy showed compromised membrane integrity and increased permeability. The activities of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) decreased by 86.08%, 82.86% and 75.47%, respectively, compared with the 0 s control group. Therefore, the accumulation of H2O2 and O2− in cells destroys the redox homeostasis, further damages the membrane structure and function, and leads to the time-dependent increase in nucleic acid leakage, soluble protein leakage and malondialdehyde (MDA) accumulation. Collectively, LTP exhibits strong antifungal activity against Alternaria sp. and shows promise for controlling postharvest diseases of plum fruit.

Comparative Longevity of Bryophyte Spores: Influence of Storage Conditions, Spore Maturity, and Plant Ecology

Bryophyte spores are known for long-distance dispersal and tolerance to adverse conditions, but their comparative longevity remains poorly understood. In this work we assessed whether moss spores are as long-lived as spores and seeds of other land plants. Spores of Funaria hygrometrica, Lewinskya acuminata, L. iberica and Ulota crispula were subjected to accelerated aging (AA: 45 °C, 60% relative humidity [RH]) and dry storage (15% RH, 20 °C) with periodic germination tests. Different maturity stages of F. hygrometrica were also included. Estimated initial viability constant (Ki), standard deviation of spore deaths’ distribution in time (σ) and time for viability to drop to 50% (P50) were determined by probit analysis from spore survival curves. Overall results showed short spore longevity for all species tested, regardless of storage conditions. P50 ranged from 0.4 to 5.7 days (AA) and 58–150 days (dry storage), indicating faster deterioration than seeds or fern spores at the same storage conditions. In the case of F. hygrometrica, spores collected at peak maturity showed the longest longevity under both storage conditions. This study suggest that moss spores may be relatively short-lived, which could be related to their chlorophyllous nature. Ecological and conservation implications of this spore character are discussed.