Comparative Responses of Ulva Intestinalis and Chlorella Sorokiniana to Sargassum Derived Biostimulant: Implications on Biomass and Pigment Enhancement

Valorization of pelagic Sargassum into a biostimulant (OJA1) for improved tomato yields and protection against bacterial and fungal phytopathogens

Several environmental and economic issues have been brought about by mass accumulations of Sargassum seaweed along the coastlines in Trinidad and Tobago, and the wider Caribbean region. Though there are many issues associated with this seaweed biomass, there remains opportunities to transform this problem into a solution. The current study presents the evaluation of a Sargassum biostimulant formulation (OJA1) and its effect on tomato. Tomato plants were foliar (0.5% v/v) treated with the OJA1 biostimulant under both greenhouse and field conditions. OJA1 significantly improved plant performance (p < 0.05) by means of increased chlorophyll (22.7%), plant height (29.3%), root biomass (34.4%), shoot biomass (49.6%), and yield (54.8%), while reducing disease severity by 37.8% for bacterial spot and 37.5% for early blight under greenhouse conditions. In field trials, OJA1 significantly increased yield and reduced disease severity across both growing seasons. Yield increases ranged from 75.6–103.2% with OJA1 alone and 114.6–154.8% when alternated with fungicides. Similarly, bacterial leaf spot and early blight severity were reduced by up to 50.6% and 61.8%, respectively, relative to the Control. Molecular mechanistic testing revealed that OJA1-treated tomato plants had more than a two-fold increase in gene transcripts responsible for abiotic/biotic stress tolerance and biosynthesis of growth hormones. Additionally, OJA1-treated plants had significantly lower DNA levels of both pathogens. Additional analysis further showed that OJA1-treated plants had significantly higher hormonal content (auxin, cytokinin, and gibberellin), and fruits had significantly higher mineral content (N, P, K, Na, and Zn) than Control plants. The results exemplify the valorisation potential of Sargassum and could contribute to sustainable agriculture and propels economic development in coastal communities.

Impact of Nutrient Conditions on Growth and Lipid Accumulation in Scenedesmus obliquus and Chlorococcum humicola as Biofuel Sources

This investigation utilizes two indigenous microalgal Species, Scendesmus obliquus and Chlorococcum humicola, to evaluate their lipid production capabilities as a potential biodiesel source under nutrient deprivation conditions, specifically nitrogen limitation at 50% (-N), phosphorus limitation at 50% (-P) and a combination of nitrogen and phosphorus starvation at 50% (-N) 50% (-P). The results indicated that lipid accumulation in Scendesmus obliquus was significantly more effective than that observed in Chlorococcum humicola at (-N50%), with a lipid content of 42.9% of dry weight, in contrast to a minimal lipid content of 15.7% observed in the control, and lipid accumulation in Chlorococcum humicola at (-N) 50% reached to 38.9% of dry weight compared with the control's 12.5% of dry weight. Furthermore, carbohydrate content elevated from 16% in the control to 41% at (-N) 50% + (-P) 50% treatment in Scendesmus obliquus, whereas the highest protein content recorded was 34% of dry weight in the control condition. In the case of Chlorococcum humicola, carbohydrate content was 40.5% of dry weight in the 50 % nitrogen deprivation treatment, with the highest protein content recorded being 29.8% of dry weight in the control condition.

Rosa sterilis S.D.Shi Pomace Enhances Mycelial Growth and Extracellular Enzyme Activity of Phallus rubrovolvatus Through Substrate Optimization

Rosa sterilis S.D.Shi pomace (RSP), a nutrient-rich by-product of fruit processing, holds considerable potential for valorization. Given the increasing interest in recycling agricultural residues for edible fungi cultivation, RSP may represent a viable, sustainable substrate component. This study evaluated the effects of partial substitution of wood chips with RSP on the mycelial growth of Phallus rubrovolvatus and aimed to identify an optimal substrate formulation. The results showed that the addition of 10% and 20% RSP to the substrates significantly promoted mycelial growth and shortened the mycelial colonization time by 4–5 days. The addition of RSP increased total phosphorus and potassium contents by 12.2%–65.9% and by 0.4- to 4.4-fold, respectively. No significant differences in the C:N ratio were observed among treatments with 5%, 10%, and 20% RSP compared to the control. Extracellular enzyme activities varied across treatments, with the 10% RSP group yielding the maximum increments in pectinase (45.9%), laccase (11.9%), xylanase (12.5%), and protease (35.6%). Although substrate pH remained relatively stable, the total organic acid content decreased, whereas the levels of citric, acetic, and succinic acids increased. Overall, 10% RSP substitution significantly enhanced mycelial growth and enzymatic activity. These findings suggest that RSP improves the mycelial ability to degrade and assimilate substrate nutrients, demonstrating its potential as an effective and sustainable substrate amendment for P. rubrovolvatus cultivation. This study provides a practical strategy for agricultural waste valorization and supports the circular utilization of biomass resources.

Effects of a Mixed Biomass of Thalassiosira weissflogii and Chaetoceros calcitrans as a Functional Feed Additive for Pacific White Shrimp (Penaeus vannamei)

Ethephon elicitation enhances biomass accumulation and phycobiliprotein production in Arthrospira platensis

Findings suggest that low-dose ethephon elicitation may be a simple strategy to enhance phycobiliprotein accumulation in Arthrospira platensis.

Potential of a phytobiotic based on Acacia concinna and the red seaweed Palmaria palmata to reduce in vitro ruminal methane production