Shrimp aquaculture is constrained by opportunistic bacterial pathogens, particularly Vibrio parahaemolyticus, whose proliferation in hatchery systems is shaped by microbial community structure. We evaluated the antagonistic activity and microbiome effects of two native Bacillus-based probiotic consortia (CN5, RS3) applied alone or combined (MIX) in shrimp larval culture water over 30 days, relative to a no-probiotic control. Treatments were assessed using standardized in vitro inhibition assays, 16S rRNA gene (V3–V4) amplicon sequencing, functional inference, and integrative multivariate and structural modeling. All probiotic treatments showed consistently high antagonistic activity against V. parahaemolyticus, whereas the control showed no inhibition. Amplicon profiling indicated treatment-associated microbiome restructuring, with increased Bacillus dominance and reduced relative abundance of Vibrio spp. under probiotic conditions. Multivariate analyses separated probiotic and control groups, and PLS-SEM identified Bacillus dominance as a central driver of antagonistic activity mediated by inferred bioactive functional potential, while water-quality variables had limited direct effects. Probiotics were administered directly to the culture water once daily after routine water exchange to 1 × 10⁶ CFU mL⁻¹ (CN5 or RS3); MIX was applied 1:1 (v/v) at the same total dose.

Seed germination and early root growth are decisive for crop establishment, yet responses to ionic environments can be strongly genotype-dependent. This study evaluated the effect of supplementing an agar-based in vitro system with a commercial NPK fertilizer on the germination dynamics and early seedling traits of Raphanus sativus L. Seeds were tested in two solid media: A (1.3% agar, no fertilizer) and AF (1.3% agar supplemented with 0.45 g of granular NPK fertilizer (15–30–15) per 200 mL medium), using a completely randomized 3 × 2 factorial design. Germination percentage and synchrony are key constituents of seedlot evaluation because they jointly capture both viability and the temporal coordination of emergence. However, final germination percentage alone does not reflect the timing and uniformity of germination, which can be critical for predicting establishment and subsequent performance. Therefore, indices such as mean germination time (MGT), coefficient of velocity of germination (CVG), and interval germination rates are frequently employed to describe germination dynamics. In addition to germination dynamics, early seedling morphometry (e.g., root and hypocotyl traits) can provide complementary information on early vigor and stress sensitivity under contrasting media or environmental conditions. Root elongation was significantly reduced by fertilization in ASD and GE, whereas AS exhibited consistently shorter roots with no significant response. PCA summarized 86.3% of the total variance in the first two components, separating treatments along a vigour/architecture axis and a germination capacity axis (%G), and hierarchical clustering identified five response groups. Overall, a low-cost agar + fertilizer system effectively discriminated genotype-specific sensitivity to an ionic environment during early establishment, highlighting the need to consider variety-dependent thresholds when using commercial fertilizers for in vitro screening.

Shrimp aquaculture is persistently constrained by opportunistic bacterial pathogens, particularly Vibrio parahaemolyticus, whose proliferation in hatchery systems is strongly influenced by microbial community structure. This study evaluated the antagonistic capacity and microbiome-level effects of two native Bacillus-based probiotic consortia (CN5 and RS3), individually and in combination (MIX), in shrimp larval culture water. Over a 30-day experimental period, probiotic treatments were compared with a no-probiotic control using a combination of standardized in vitro inhibition assays, 16S rRNA gene (V3–V4) amplicon sequencing, functional inference, and integrative multivariate and structural modeling. All probiotic treatments exhibited consistently high antagonistic activity against V. parahaemolyticus, whereas the control did not show inhibition. Amplicon-based profiling revealed a clear treatment-associated restructuring of the water microbiome, characterized by increased Bacillus dominance and reduced relative abundance of Vibrio spp. under probiotic conditions. Multivariate analyses demonstrated robust separation between probiotic and control treatments, and partial least squares structural equation modeling identified Bacillus dominance as a central driver of antagonistic activity, mediated through inferred bioactive functional potential. Water-quality variables showed limited direct influence within the modeled framework. Collectively, these results indicate that native probiotic consortia are associated with stable Bacillus-dominated microbial regimes and strong in vitro suppression of V. parahaemolyticus, supporting their potential role as ecological tools for microbial management in shrimp hatchery systems.