Abstract: Viral pathogens persistently threaten global aquaculture by causing serious economic losses and compromising food security. This urgency highlights the need for sustainable alternatives to conventional control methods. Lactic acid bacteria (LAB), particularly Lactobacillus strains, have emerged as promising biocontrol agents due to their generally recognized as safe (GRAS) status and multifaceted antimicrobial properties. This review synthesizes current knowledge on the mechanisms of antiviral properties of Lactobacillus in aquaculture. The first line of defense involves direct virion inactivation through physicochemical interactions that sequester viral particles, combined with capsid destabilization by Lactobacillus metabolites. Subsequently, probiotics modulate host cell receptors to reduce viral attachment and entry. Finally, Lactobacillus strains stimulate systemic and mucosal antiviral immunity in aquatic hosts. By integrating these mechanisms, Lactobacillus establishes a multi-layered defense against viral intrusion. These mechanistic insights can guide the strategic application of Lactobacillus to enhance biosecurity and support the sustainable growth of the aquaculture industry.

The sustainable management of diseases in marine fish aquaculture remains a critical challenge, thus exploring the alternative to control the disease is needed. Probiotics offers the advantages for disease control compared to other strategies and for some extremophiles, particularly halophilic bacteria, are gaining attention. This minireview examines the probiotic potential of halophilic bacteria as eco-friendly alternatives for disease control in marine fish farming. Halophilic bacteria, naturally adapted to high-salinity environments through specialized physiological mechanisms, offer distinct advantages over conventional probiotics that often fail to survive in marine conditions. Various studies have demonstrated that halophilic bacteria exhibit broad-spectrum antibacterial, antiviral, and antifungal activities while enhancing growth performance, digestive enzyme activity, and immune parameters in aquaculture species. Given the substantial contribution of marine fish to global food security and the specific challenges faced in their farming, halophilic bacteria particularly halophilic lactic acid bacteria with Generally Recognized as Safe (GRAS) status represent promising and sustainable alternatives for health management in aquaculture.

The sporicidal activity of sodium linear alkylbenzene sulfonate (LAS), a major anionic surfactant used in detergents, against Bacillus subtilis, B. cereus, and Geobacillus stearothermophilus was evaluated. Bacterial suspensions including spores were treated with 0.01–10 mM LAS under various pH (2.7–7.8) and temperature conditions (25°C–70°C). Zeta potential analysis and spore quantification were performed to explore the mechanism of action of LAS. LAS displayed pronounced sporicidal activity only under both acidic conditions (pH ≤5) and elevated temperature (≥50°C). In the presence of 1 mM LAS in 10 mM citric acid (pH 2.7) at 70°C, B. subtilis spore counts were reduced by >5.7 log₁₀ colony forming units/mL within 5 min. Zeta potential measurements and HPLC quantification indicated enhanced penetration of LAS into spores at both low pH and high temperature. Considering that the typical LAS concentration in commercial cleaning formulations is approximately 1 mM, the present findings suggest that common detergent systems can achieve significant sporicidal activities when combined with high-temperature washing protocols.

This study investigated the effect of preheating on high hydrostatic pressure (HHP)-induced germination of Bacillus subtilis spores. HHP-induced germination at 100 MPa was accelerated by preheating at 50–70 °C and suppressed at 80–100 °C. Conversely, HHP germination induction at 600 MPa was accelerated with increasing preheating temperature from 50 to 100 °C. Additionally, preheating at 90 °C suppressed HHP-induced germination at 100–300 MPa, exerted no effect at 400–500 MPa, and promoted induction at 600 MPa. In conclusion, the impact of preheating on HHP-induced germination varies with both pressure level and preheating temperature.

Endophytic beneficial microorganisms are widely used in agriculture for promoting plant growth and enhancing plant defense mechanisms. This study aimed to characterize endophytic fungi isolated from the roots of coffee plants cultivated in organic agroforestry systems and evaluate their potential as biocontrol agents against fungal pathogens, as well as their ability to promote plant growth. Biocontrol activity was assessed using in vitro dual-culture assays on potato dextrose agar, measuring the inhibition of pathogen growth. Plant growth promotion was evaluated by co-cultivating Arabidopsis thaliana seedlings with fungal isolates on Murashige and Skoog medium. Isolates were further subjected to both qualitative and quantitative biochemical characterization. A total of 18 endophytic fungal strains were identified and classified in five genera: Colletotrichum, Fusarium, Simplicillium, Lasiodiplodia and Trichoderma. Among these, ten Trichoderma isolates demonstrated strong antagonistic activity against selected fungal pathogens and significantly enhanced the growth of Arabidopsis seedlings in vitro. These beneficial effects were associated with the production of siderophores and indole-3-acetic acid, as well as the apparent nitrogen availability –– likely mediated through interactions with nitrogen-fixing bacteria.

In winter, condensation often causes fungal contamination on glazing beads inside the lower frames of windows. In this study, live and dead fungi present on 12 windows were examined during different seasons. Cladosporium halotolerans was predominantly detected, followed by Aureobasidium pullulans, both of which are common dark fungi. The total fungal including both live and dead fungi was quantified by real-time PCR. A significant correlation was noted between the counts of live and total fungi on different beads. The average live fungal count on beads sharply decreased under severe conditions, such as exposure to drought and heat, from February–October. Comparatively, the number of dead fungi gradually decreased as fragments remained attached to beads. Notably, dead cell counts were higher than those of live cells, with dead fungi contributing to dirt more than live fungi did. Therefore, common fungicidal treatment is ineffective for cleaning beads. The degree of dirt on beads likely depends on the melanin levels in dead fungal cells (predominantly C. halotolerans). Despite the dead cell counts of C. halotolerans decreasing to one-quarter of the initial values from winter to autumn, dirt levels on beads remained unchanged.

This study characterized the microbiota on lip-contact surfaces of worn non-woven fabric masks and evaluated the effects of commercially available mask sprays. Masks worn by six healthy volunteers were sampled, cultured anaerobically, and analyzed by 16S rRNA gene PCR-RFLP and sequence analysis, since anaerobic cultures are known to yield a larger and more diverse microbial community of the microbiota on worn non-woven fabric masks (Maruyama et al. 2022). The mean bacterial concentration on worn masks was (1.4 ± 0.9) × 10³ CFU/mL. Among 299 isolates, Cutibacterium (75.3%) and Staphylococcus (19.4%) were predominant. Several sprays markedly reduced bacterial counts (to 10¹–10² CFU/mL), whereas others showed limited effects. Overall, mask sprays variably reduced bacterial contamination on lip-contact surfaces of worn non-woven fabric masks.