Lactic acid bacteria (LAB) play a crucial role in probiotics, functional foods, and sustainable biotechnologies due to their ability to produce bioactive metabolites such as short-chain fatty acids, bacteriocins, vitamins, and exopolysaccharides. These metabolites aid in gut health, pathogen inhibition, and enhanced productivity in the food, pharmaceutical, and aquaculture industries. However, the high production cost remains a major challenge, necessitating cost-effective media formulations and bioprocess optimization. This review explores strategies for maximizing LAB yields and functionality through the precision control of key cultivation parameters, including temperature, pH, and agitation speed, ensuring probiotic viability in compliance with regulatory standards (≥10⁶ CFU/g or mL). Furthermore, advances in metabolic engineering, synthetic biology, and the utilization of agro-industrial by-products are driving cost-efficient and eco-friendly LAB production. By integrating scalable fermentation technologies with sustainable resource management, LAB have the potential to bridge the gap between food security, environmental sustainability, and biotechnological innovation. This review provides a comprehensive overview of recent advances in LAB cultivation and bioprocess optimization, ensuring high-quality probiotic production for diverse industrial applications.

Marine microalgae may produce antibacterial substances. At the exponential phase of growth, four species of marine microalgae were examined for their potential to create secondary metabolites that limit the growth of Vibrio harveyi: Nannochloropsis oceanica, Chaetoceros gracilis, Isochrysis sp., and Thalassiosira weissflogii. V. harveyi is a pathogenic bacteria that can cause severe mortality and loss in aquaculture. Disc diffusion assay and co-culture assay were used to determine antibacterial activity. On TSA % NaCl media, the disc impregnated with microalgae and extracted with ethanol, methanol, saline water, and dimethyl sulfoxide (DMSO) was tested against V. harveyi at concentrations of 1.0 × 10⁵, 10⁶ and 10⁷ CFU mL⁻¹. The disc diffusion assay revealed that N. oceanica extracted with ethanol had the largest inhibitory zone against V. harveyi. Meanwhile, only N. oceanica, Isochrysis sp., and T. weissflogii reduced the growth of V. harveyi (10⁵ CFU mL⁻¹) in the co-culture assay (p < 0.05). The current findings reveal that the hydrophilic chemicals in microalgae extract have antibiotic activity against the highly virulent V. harveyi, which causes vibriosis, a serious disease in farmed fish and aquaculture cultivation around the world.

The immune response of Tiger grouper (E. fuscoguttatus) broodstocks and its passive transfer of maternal antibodies to eggs and larvae were evaluated following vaccination with an inactivated V.harveyi. Tiger grouper broodstock (mean BW 8.66 ± 0.09 kg, n=19) were vaccinated intraperitoneally (IP) and followed by a booster two weeks post vaccination, while Controlled Non-vaccinated (CG) broodstock were IP injected with PBS. The serum antibody level against V.harveyi was monitored for two weeks on post-vaccination and monthly up to 5 months post-vaccination. This study showed that the Vaccinated Group (VG) broodstock induced significantly (P<0.05) higher in specific IgM antibody level against V.harveyi as compared to the CG, which in turn induced a marked increased (P<0.05) in specific IgM in eggs and larvae produced from VG broodstock at 14 weeks post vaccination. The findings from this study suggested that inactivated V.harveyi vaccines were able to stimulate the immune response in broodstock and passively transferred the maternal antibody to their eggs and larvae.

The current study evaluated the effects of dietary supplementation of Triphala (TR) on yellow perch (Perca flavescens) growth performance, immune response, related gene expression, and intestinal histological structure. The experimental design included four groups: one control group (0% TR/ kg diet) and three TR-supplemented groups with 2, 4, and 6%/kg diet for four weeks and each group was allocated in triplicates with 30 fish each. Sampling included three fish from each replicate for evaluating immune response and gene expression. Findings showed that Triphala markedly improved growth performance, Immunoglobulin M (IgM) levels, lysozyme activity, and Nitric Oxide (NO) activity with the most significant (p < 0.05) results for 6% TR/kg diet group. The TR groups also showed significantly decreased glucose and cortisol concentrations with the lowest values for the 6% TR/kg diet group. Moreover, TR-incorporated groups revealed significantly upregulated expression (p < 0.05) of growth [Insulin-Like Growth Factor-1 (IGF-1)] and immune [Alpha 2 Macroglobulin (A2M), Serum Amyloid A (SAA) and Complement Component C3 (CCC3)] genes in incorporated groups, specially the 6% TR group. Moreover, the intestinal morphometric histological analysis revealed that villus length was increased in a dose-dependent manner, coping with other enhanced parameters. Current results endorse the positive effects of Triphala incorporation on yellow perch farming as a safe alternative option to enhance growth performance, immune response, related gene expression, and intestinal histology.

Background: Vibrio alginolyticus is a gram‐negative bacterium responsible for mass mortality in cultured groupers, leading to significant economic losses in the aquaculture industry. Although preventive measures such as chemical treatments, antibiotics, and pesticides have been employed, these methods have been reported to be toxic to the environment and contribute to the development of antimicrobial resistance (AMR) in treated fish. Methods: In this study, a giant Myoviridae phage strain (ValKK1‐20) was isolated from the sandy area of Kota Kinabalu, Sabah, Malaysia. The purified phage was characterized based on transmission electron microscopy (TEM) and its genomic DNA. The adsorption assay and one‐step growth analyses were conducted to predict the critical phase of ValKK3 infection. Results: TEM analysis revealed that the phage possessed an elongated head with a sheathed tail, resembling members of the T4‐like Myoviridae group. The genome characterization revealed that the phage belongs to T4 phage with a genome size 248,088 bp with 41.2% G + C content and 390 predicted open reading frames. Additionally, it demonstrated a short eclipse period of 36 min and a latent period of 48 min, with a large burst size of approximately 174 plaque‐forming units (PFU) per cell. Conclusions: In conclusion, this study highlights the potential of selected phage ValKK3 as a biocontrol agent against V. alginolyticus , offering a promising alternative for sustainable aquaculture management.