Seaweed Extracts Research Articles

Combined effects of biostimulants, N level and drought stress on yield, quality and physiology of greenhouse-grown basil

Precise nitrogen (N) supply is an agronomic practice of crucial importance to achieve optimal crop performance without compromising product quality. However, excessive use of synthetic N fertilizers may have deleterious effects on both agroecosystem and human health. Thus, the development and use of strategies aiming to ameliorate the losses caused by water constraints and N deficiency are essential for fostering resilient and sustainable agroecosystems. In this regard, the impact of three drought stress levels (DS) [100%, 80% and 60% of the field capacity (FC)] in combination with four N supply rates (0, 50, 100 and 150 kg ha−1) on sweet basil cultivated in a protected environment was investigated. The interactive biostimulatory action of Kelpstar® seaweed extract (SWE) and Tyson® protein hydrolysate (PH) was also explored. The study focused on the effects of these treatments on yield, physiological attributes, functional traits, and volatile compounds profile. Drought stress led to a reduction in yield by 12.5% and 21.1% under irrigation at 80% and 60% FC, respectively, compared to well-watered plots (100% FC). Furthermore, drought stress levels linearly decreased total leaf area (-15.4% and -26.2% for DS80 and DS60, respectively), stomatal conductance (-14.2% and 34.1% for DS80 and DS60, respectively), nitrogen use efficiency (NUE) (4.0% and 10.0% for DS80 and DS60, respectively), and volatile compounds, such as trans-2-hexanal, 1-octen-3-ol and α-bergamotene. Conversely, an increase in N application rate positively influenced yield (8.6% and 12.2% for N100 and N150, respectively), total leaf area (22.2% and 16.5% for N100 and N150, respectively), specific leaf area (SLA), total chlorophyll (7.7% for N150), nitrate content, and the presence of specific volatile compounds, such as 1-octen-3-ol and α-bergamotene, when compared to no N application. Seaweed extract application caused an upsurge in yield (+17.5%), stomatal conductance (+25.8%), WP (+13.5%), total chlorophyll (+2.3%), nitrate (+3.4%), phenolics (+14.2), ascorbic acid (+28.2), as well as, 1-octen-3-ol, β-cis-ocimene, linalool and eugenol, compared to the control. Similarly, plant protein hydrolysate increased yield (+16.1), stomatal conductance (+10.4), WP (+13.7), total chlorophyll (+4.3), phenolics (+10.7%), ascorbic acid (+9.7%), β-cis-ocimene and eugenol, compared to the control. Notably, the increased yield, improved quality, and enchanced physiological traits observed after biostimulant application, especially under drought stress or N deficiency conditions, underscore the potential role of biostimulants in increasing resilience of basil plants. Thus, the foliar application of SWE and PH offer a valuable strategy for enhancing plant yield and quality under sub-optimal conditions, while simultaneously enhancing water and N use efficiency.

Potential of algal-based products for the management of potato brown rot disease

BackgroundRalstonia solanacearum causes potato brown rot disease, resulting in lower crop’s production and quality. A sustainable and eco-friendly method for controlling the disease is required. Algae’s bioactive chemicals have shown the potential to enhance plant defenses. For the first time, the efficacy of foliar application of Acanthophora spicifera and Spirulina platensis seaweed extracts, along with the utilization of dried algal biomasses (DABs) of Turbinaria ornata and a mixture of Caulerpa racemosa and Cystoseira myrica (1:1)on potato yield and brown rot suppression were investigated under field conditions. Field experiments were conducted in three locations: Location 1 (Kafr Shukr district, Kaliobeya governorate), Location 2 (Moneira district, Kaliobeya governorate), and Location 3 (Talia district, Minufyia governorate). Locations 1 and 2 were naturally infested with the pathogen, while location 3 was not. The study evaluated potato yield, plant nutritive status and antioxidants, soil available nitrogen-phosphorus-potassium (N-P-K), and organic matter percentage. Additionally, the shift in soil microbial diversity related to R. solanacearum suppression was examined for the most effective treatment.ResultsThe results revealed that seaweed extracts significantly increased potato yield at all locations, which correlated with higher phosphorus absorption, while T. ornate DAB increased potato yield only at location 2, accompanied by noticeable increases in soil nitrogen and plant phosphorus. The mixed DABs of C. racemosa and C. myrica demonstrated greater disease suppression than foliar applications. The disease-suppressive effect of the mixed DABs was accompanied by significant increases in flavonoids and total antioxidant capacity (TAC). Moreover, the application of mixed DABs increased soil bacterial biodiversity, with a higher abundance of oligotrophic marine bacterial species such as Sphingopyxis alaskensis and growth-promoting species like Glutamicibacter arilaitensis, Promicromonospora sp., and Paenarthrobacter nitroguajacolicus in all three locations compared to the untreated control. Klebsiella sp., Pseudomonas putida, and P. brassicacearum abundances were increased by the mixed DABs in Location 1. These species were less abundant in locations 2 and 3, where Streptomyces sp., Bacillus sp., and Sphingobium vermicomposti were prevalent.ConclusionsThe results demonstrated that the used seaweed extracts improved potato yield and phosphorous absorption, while the mixed DABs potentially contributed in disease suppression and improved soil microbial diversity.

Biostimulants and Nano-Potassium on the Yield and Fruit Quality of Date Palm

Although chemical fertilization has been excessively used for a high yield of fruit trees, it causes many problems such as nitrate accumulation, soil deterioration, and food safety and quality decline; therefore, the dependency on the usage of biostimulants has become paramount when aiming to reduce the usage of chemical fertilizers, improve the fruit quality, and increase the shelf life of the fruits. The present experiment was conducted during the 2021–2022 seasons to study the effect of the foliar of yeast extract (YE), fulvic acid (FA), moringa leaf extract (MLE), seaweed extract (SWE), and nano-potassium (K NPs) alone or after combining each one of them individually with K NPs on the yield and fruit physical and chemical characteristics of date palm cv. Samani. The results show that the application of 0.2% YE + 0.02% K NPs led to the highest results in yield, bunch weight, fruit weight, flesh weight, fruit content from soluble solids, total and reduced sugars, VC, total chlorophyll, and carotene. Additionally, the results also demonstrate that the application of 0.4% SWE + 0.02% K NPs, 0.4% FA + 0.02% K NPs, and 6% MLE positively affected the previously mentioned measurements compared with the control or the other sprayed treatments.

Effect of seaweed extracts (Ascophyllum nodosum) on yield and nut quality in hazelnut

Effect of seaweed extracts (<i>Ascophyllum nodosum</i>) on yield and nut quality in hazelnut

Polysaccharides from red seaweeds: Effect of extraction methods on physicochemical characteristics and antioxidant activities

Seaweed polysaccharides are reported to possess biological and medicinal properties. Specifically, the antioxidant activity of seaweed extracts is the subject of intensive research due to ever-increasing demands from the food and pharmaceutical industries. The structure and composition of polysaccharides (carrageenan, xylan) extracted from four red seaweed species: Chondrus crispus (CC), Ahnfeltiopsis devoniensis (AD), Sarcodiotheca gaudichaudii (SG) and Palmaria palmata (PP) were compared and correlated with their antioxidant activity. Crude polysaccharide extracts were characterized by NMR (1H and 13C), HPLC-SEC, and FTIR spectroscopy. Total phenolic content (TPC), total sugars, sulfate and protein content were determined using spectrophotometric methods. The antioxidant capacity of each fractionated polysaccharide sample was evaluated by the following methods: DPPH (2,2-diphenyl-1-picrylhydrazyl radical), ABTS (2,2-azino-bis-[3-ethylbenzothiazoline-6-sulfonic acid]), superoxide dismutase (SOD), ferric-reducing power in FRAP (Ferric-reducing Antioxidant Power) assays, and the hydroxyl radical (OH) scavenging capacity assay. The highest antioxidant activity was found in extracts from A. devoniensis (ι/κ hybrid carrageenan), while the lowest was in P. palmata (xylans). Moreover, Chondrus crispus extracts did not possess SOD inhibition activity. Polysaccharides evaluated in this study offer high potential for applications in the food, pharmaceutical and biotechnology industries.

Plant Growth Bio-stimulants of Seaweed Extract (Sargasum boveanum): Implications Towards Sustainable Production of Cucumber

The purpose of this experiment was to compare the growth and quality of cucumber fruits, in response to different concentrations (C0, C0.75, and C1.5 g L-1) and different application methods (M1: foliar sprays, M2: fertigation, M3: combined foliar sprays and fertigation) of seaweed extract (SwE). The simultaneous use of the method and different concentration of SwE increased the fresh weight of the leaf, fruit weight, yield, number of leaves, evaporation, fruit length, fruit diameter and firmness, stomatal conductance, and nitrate concentration of fruit. On the other hand, the highest amount of fruit firmness (69.25 and 69.27 N) was observed in M2C0.75 and M2C1.5 compared to other treatments, respectively. The M1C0.75 treatment increased the fruit diameter by 26.52% more than the M1C0 treatment. Fruit weight, fruit length, and yield were in the following order in different treatments, M1C1.5˃ M1C0.75 ˃ M3C1.5. So that only in the M1C1.5 treatment, fruit weight, yield, and fruit length were 25, 52.55, and 25.86% higher than the M1C0 treatment, respectively. Generally, the M1 and M3 in concentrations of 0.75 and 1.5 created better plant growth, fruit shape, and quality characteristics compared to the second method (M2) and the C0 treatment. Therefore, the concentration of 1.5 g L-1 and the use of foliar spraying methods, and the combination of foliar spraying and fertigation can be recommended to achieve the maximum yield and quality of cucumber fruits.

The effect of seaweed foliar application on yield and quality of apple cv. ‘Golden Delicious’

Apple is one of the most important horticultural products, and the present study aimed to evaluate the effects of foliar application of seaweed extract on the yield, physiological traits, and concentrations of some elements in apple cv. ‘Golden Delicious’. The experiment was performed as a randomized complete block design with 5 replications in an orchard of Semirom. Treatments were included 2 extracts of seaweed Seafer-100 (800 and 1,200 mL/1000 L) and Macys BC28 (2,000 and 2,500 mL/1000 L) as well as control (spraying distilled water). In this study, we measured traits including yield characteristics (yield/tree and hectare, fruit weight, firmness, and diameter), physiological traits (titratable acidity, soluble solids content, ascorbic acid, proline, phenol, soluble sugars concentration, chlorophyll a, b, total chlorophyll, carotenoids, peroxidases, ascorbate peroxidases, catalases, proteins, and relative leaf-water content), and elements (N, P, K, Zn, Fe, Mg, and Cu). The general results showed that the application of seaweed extract lead to a significant increase in most of the studied traits compared to the non-application of this treatment. This means that by increasing the concentration of both seaweed extracts, yield characteristics, most of the physiological traits, and some elements increased significantly. After the use of seaweed extract, the concentration of N, Fe, and P, chlorophyll a and b, relative water content, fruit size, and yield increased. In general, the use of seaweed extract improved the fruit quantity and quality of this important product. Therefore, it is recommended to use seaweed extract in ‘Golden Delicious’ apple orchards.

Evaluation of probiotic growth stimulation using prebiotic ingredients to optimize compounds for in ovo delivery.

The use of probiotics, prebiotics and synbiotics in poultry diets beneficially stimulates the gut microbiome thus promoting the health and welfare of the animals. In this study, we analyzed 7 poultry probiotics (Lactobacillus plantarum - B1 and B4, Lactobacillus rhamnosus - B3, Bifidobacterium lactis - B2, Carnobacterium divergens - B5, Propionibacterium thoenii - B6, Clostridium butyricum - B7) and 12 prebiotics, differing in chemical composition and source of origin (fungi, algae, animal, etc.). The main goal of our research was to select the most promising candidates to develop synbiotic combinations. We determined the growth kinetics of all probiotics in the presence of prebiotics in a series of in vitro studies to select optimal combinations. Five out of seven investigated probiotics were significantly stimulated by astragalus polysaccharide, and this prebiotic was characterized in our work as the most effective. Moreover, in the case of three probiotics, B2, B3 and B4, significant growth stimulation has been found when beta-glucan, vegetable protein hydrolysate and liquid seaweed extract were supplied. Strain B1 (L. plantarum) was stimulated by 6 out of 12 prebiotics. The growth of B4 (L. plantarum) and B2 (B. lactis) was enhanced by prebiotics after 2 h of incubation. A high growth rate of 3.13% was observed in the case of L. plantarum (B4) and a 3.37% higher rate for B. lactis (B3), compared to the growth of probiotics in the control medium with glucose but no prebiotics. The best candidates for synbiotic combinations based on this in vitro work are the strains belonging to L. plantarum (B4), L. rhamnosus (B3) and B. lactis (B2), consistent with prebiotics such as astragalus polysaccharides and vegetable protein hydrolysate. These combinations will be subject to future in vivo poultry trials involving the in ovo microbiome modulation.

Soil Application of Sea Weed Extract Granules and Foliar Application of Nano ZnO to Bt Hybrid Cotton to Vertic inceptisols

Bt hybrid cotton was significantly benefitted by the soil application of Sagarika sea weed extract granules at 25 kg ha-1 yr-1 along with the recommended basal fertilizers dose or foliar application of nano ZnO 4% at 0.04% at squaring and flowering stages. These treatments significantly enriched index leaf residual P and Zn content beyond 20 μg g-1 fresh weight during boll development stage and this resulted in significant improvement in lint yield by 7.5% i.e. 35 kg lint ha-1 yr-1, C:B ratio by 5.0% and net returns to the tune of ₹. 5000 ha-1 over alone 100% RDF in eroded Vertic inceptisols deficient in N, Mg, S, Zn and B. Excess rains at seedling and vegetative stage followed by drought at reproductive stages in both years, reduced the economic viability of seed treatment with bio-stimulants and foliar applications besides soil and foliar application of Zn, S, B alone or together to Bt hybrid cotton.

Influence of seaweed extracts on the degradation and effectiveness of 3,4-dimethylpyrazole phosphate

3,4-Dimethylpyrazole phosphate (DMPP) is acknowledged as one of the most efficient nitrification inhibitors (NIs); however, researchers have suggested that its effectiveness needs to be further improved. The authors combined the biostimulant seaweed extract (SE) with DMPP and conducted an indoor incubation experiment to initially investigate the impact of the influence of SE on the degradation and effectiveness of DMPP. Meanwhile, a method for the extraction and determination of DMPP was developed. DMPP performed better, with a longer effective time in loess than black soil, and SE showed a delayed effect on DMPP degradation of DMPP at the beginning of the incubation and then accelerated the degradation process. This was attributed to the adsorption effect of SE on DMPP, consequently reducing its effectiveness. The SE delayed the hydrolysis of urea in various soils; however, no significant impact on urease activity was observed (P &lt; 0.05) (P &lt; 0.05). Furthermore, it also increased potential nitrification rate (PNR) from 10 to 21 days and promoting the rapid transformation of NH4+-N in black soil. The SE reduced PNR within 21 days and inhibited nitrification in loess. In addition, the SE appeared to mitigate the adverse effects of excessive nitrogen on microorganisms The combination of DMPP and SE was not conducive to the inhibition of soil nitrification, and this formulation in field applications requires further investigation.

Foliar application of Ascophyllum nodosum on improvement of photosynthesis, fruit setting percentage, yield and quality of tomato (Solanum lycopersicum L.)

In recent days, liquid formulations of brown seaweed extract, Ascophyllum nodosum used as a biostimulant in agriculture. Various studies suggest that A. nodosum enhanced the growth and yield of agriculturally important crops, but still, there is a lack of information about the biostimulation effects on photosynthesis, flowering and fruit setting of tomato. Hence, the present study aimed to know the effect of foliar application of A. nodosum on photosynthesis, flowering, fruit setting, yield and quality of tomato. A biostimulant product, MC Set with A. nodosum extract applied to tomato as a foliar spray at rates of three different concentrations such as 1.0 L ha−1 (MS 1), 2.0 L ha−1 (MS 2), 3.0 L ha−1 (MS 3) for six times during flowering of 2nd (30 Days after transplanting – DAT), 3rd (40 DAT) and 4th (50 DAT) cluster and fruit setting of 2nd (60 DAT), 3rd (70 DAT) and 4th (80 DAT) cluster respectively. The MC Set treatments enhanced the plant photosynthesis, flower number and fruit number per cluster, yield and quality traits of tomato. However, the middle concentration MS 2 showed highest photosynthetic rate, stomatal conductance, SPAD value, flower and fruit in 2nd, 3rd and 4th cluster. It also had better average fruit weight and yield per plant and hectare and enhanced the quality parameters such as total soluble solids, ascorbic acid content, lycopene and total sugars compared to control and other two concentrations of MS Set. Hence, using A. nodosum extract on tomato growth could be a better sustainable crop production method.

Biorefinery as a tool to obtain multiple seaweed extracts for cosmetic applications

Seaweeds have been identified as a valuable source of natural ingredients and their use in cosmetics is being studied increasingly. This work sought to understand the possible uses of three species of brown algae present along the Portuguese coast: Bifurcaria bifurcata, Saccorhiza polyschides and Fucus spiralis. Considering the idea of more sustainable use of resources, two extracts (water (W) and ethanol (E)) and two fractions (polysaccharides (P) and residues (R)) were obtained employing a biorefinery process. The extracts and fractions were evaluated in terms of antioxidant capacity (ABTS•+, DPPH•, •NO, O2•− and FRAP assays), anti-hyperpigmentation capacity (tyrosinase inhibition), and evaluated in terms of biocompounds (phenolic compounds and pigment content). The biochemical analysis revealed that F. spiralis contain more lipids and carbohydrates than the other species, while S. polyschides has more proteins and ashes. Fucus spiralis showed the most promising results, regarding the antioxidant assays, tyrosinase inhibition, highest phenolic compound concentration, total chlorophylls and total carotenoids. In a biorefinery concept, F. spiralis from the autumn season would be the most promising candidate as all extracts and fractions have potential commercial value. Bifurcaria bifurcata also has its merits in antioxidant activities and the content of phenolic compounds.

Effect of water quality, mineral fertilizer levels and methods of adding seaweed extracts on reducing salt stress, growth and yield of cauliflower.

A field experiment was conducted at one of the research stations of the College of Agricultural Engineering Sciences / University of Baghdad in Al-Jadiriyah region for the autumn season 2021-2022, located within 33.27 north latitude and 44.39 east longitude, in Clay soil with a Split Plot Design design and with three replicates to study the effect of Irrigation water quality, mineral fertilizer and methods of adding marine extracts to reduce salt stress and cauliflower growth and yield. The experiment included three factors: irrigation with two types of water, regular irrigation water (tap water) with an electrical conductivity of 0.9 dSm-1, and the second is saline water (wastewater) with an electrical conductivity of 4.8 dSm-1 and two levels of mineral fertilizer 50% and 100% of Fertilizer Recommendation and Extracts with six different levels of supplementation (S0, S1, S2, S3, S4 and S5). Cauliflower seedlings, Prassica oleracea, and cultivar Megha were transferred to the field on 9-15-2021. Nitrogen was added by 300 kg. N ha-1 in urea (46% N) and phosphate in 100 kg. P ha-1as triple superphosphate (20% p)and potassium by 150 kg. K ha-1 is in the form of potassium sulfate (42% K). Soil samples were taken over the length of the experiment and periods (30, 45, 60 and 75 days) to estimate the electrical conductivity in the soil. At the end of the season, the yield of cauliflower was estimated. The results showed the significant effect of irrigation water quality, mineral fertilizer, and methods of adding marine extracts in reducing the electrical conductivity of the soil and increasing the cauliflower yield and treatment (W1M2S5) achieved the highest significant increase in cauliflower yield, with an increased average of 47.97%, followed by treatment (W2M2S5), with an increased average of 42.63%. Keywords: water quality, seaweed extracts

Biostimulants in the Production of Forage Grasses and Turfgrasses

Biostimulants are becoming more prevalent in the production of forage and turfgrasses. Many can be classified as natural biostimulants, including humic acids (HA), fulvic acids (FA), protein hydrolysates (PHs) and seaweed extracts (SWE), in addition to chitosan, silicon, inorganic compounds, beneficial fungi, bacteria and synthetic biostimulants. The article reviews recent research on the effects of biostimulants in the cultivation of forage grasses (perennial ryegrass, annual ryegrass, Festulolium, Kentucky bluegrass, annual bluegrass, orchard grass and timothy-grass) and turfgrasses (perennial ryegrass, Kentucky bluegrass, tall fescue, red fescue and creeping bentgrass). Literature analysis suggests that biostimulants enhance the quality of grasses, augment their tolerance to environmental stresses, facilitate nutrient uptake and improve the visual aspect of grasses. While biostimulants cannot replace fertilisers, they can significantly improve crop effectiveness in utilising the nutrients present in the fertilisers. This paper also briefly describes the legal and regulatory status of biostimulants with a focus on the EU and PL.

Effect of Seaweed Extracts on the Growth, Flower Yield and Quality of Dahlia (Dahlia variabilis) C.V. Aditya Birla

An experiment entitled “Effect of seaweed extracts on the growth, flower yield and quality of Dahlia (Dahlia variabilis) c.v. Aditya Birla” was conducted to evaluate the response of dahlia to different growth regulators, Kelp @ 2ml and 4 ml and Biovita @ 2ml and 4 ml. Thirteen different treatment combinations were replicated thrice in a Randomized Completely Block Design. The investigation revealed that Biovita was very effective and recorded maximum days to seed germination, plant height, number of leaves, stem diameter, secondary branch number. Leaf area Significant influence of growth regulators was observed on various vegetative parameters. Flower diameter, flower number, diameter and fresh weight increased Significant influence of growth regulators was observed on various foral parameters. Highest flower numbers per plant and flower yield per ha was recorded treatment T11 (4 ml L-1Biovita, 5 days interval). Treatment T11 recorded higher net realization Rs. 506700 which was followed by treatment cost of cultivation with of Rs.170500.. Furthermore, highest Cost benefit ratio was recorded under treatment T11 (1:2.97).

Effects of extracting solvents on phytochemical, antioxidant, and antibacterial activity of some seaweeds from the Bay of Bengal offshore Island

Seaweed is a rich source of bioactive compounds. Therefore, searching of natural antioxidant and antibacterial agents as alternatives to a synthetic counterpart is of great interest. The effects of various extracting solvents (viz. methanol, ethanol, and acetone) on the phytochemical content, antioxidant, and antibacterial activity of seven seaweeds consisting of three brown seaweeds (Sargassum natans, Sargassum fluitans, Spatoglossum asperum), three red seaweeds (Hypnea pannosa, Hypnea musciformes, Porphyra linearis) and one green seaweed (Ulva lactuca) were evaluated. The antioxidant capacity of crude extracts was evaluated by total antioxidant activity (TAA), 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2, 2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and cupric reducing antioxidant capacity (CUPRAC) assays. Seaweed extracts were also tested against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa by agar well diffusion method. The total phenolic content (TPC) of seaweed extracts varied significantly (P < 0.05) ranging from 51.08 ± 0.72–74.62 ± 1.15 mg GAE/g. Methanolic extracts of S. natans showed significantly the highest TPC, total flavonoid content (79.22 ± 5.21 mg QE/g), and TAA (57.79 ± 4.35 mg AA/g) than other seaweed extracts. Methanolic extracts of S. natans also exhibited the highest DPPH and ABTS radical scavenging effects (EC50 = 0.74 ± 0.04 and 0.14 ± 0.01 mg/ml, respectively). While, methanolic and ethanolic extracts of S. natans showed significantly the highest effective concentration (ECA0.50) value (0.19 ± 0.02 mg/ml and 0.14 ± 0.02 mg/ml, respectively) of CUPRAC. Pearson's correlation test and principal component analysis showed the relation between TPC and various antioxidant activity assays of seaweed extracts. The seaweed methanolic extracts showed a comparatively higher zone of inhibition against all the bacterial strains than other solvent extracts. However, all the solvent extracts of U. lactuca were almost inactive against all the bacterial strains. The results of this study demonstrated that methanolic extracts of brown seaweeds showed comparatively better antioxidant and antibacterial activity, which could be used in the food and pharmaceutical applications.

Extension of shelf life of Nile tilapia (Oreochromis niloticus) fillets using seaweed extracts during refrigerated storage.

The effects of seaweed (Padina tetrastromatica, Sargassum natans, and Sargassum fluitans) ethanolic extracts on the quality and shelf life extension of Nile tilapia (Oreochromis niloticus) fillets were investigated during refrigerated storage for 20 days. Each of the seaweed ethanolic extracts solution (2%, w/v) was used for dipping the fish fillets for 10 min at 4°C. The control and seaweed extract-treated fillets were stored at 4 ± 1°C in air-tight polyethylene bags, and chemical, bacteriological, and sensory evaluation were performed at every 4 days' intervals. During the storage period, P. tetrastromatica extract significantly (p < .05) reduced the increment of pH, peroxide value, thiobarbituric acid reactive substances, and total volatile basic nitrogen values in Nile tilapia fillets compared to other seaweed extracts-treated and untreated fillets. The maximal total viable count of control, P. tetrastromatica, S. natans, and S. fluitans extracts-treated fillets was 6.53, 7.11, 6.75, and 7.10 log CFU/g at the 8th, 20th, 12th, and 16th days of storage, respectively. The total psychrotrophic count of control and seaweed extracts-treated fillets was also significantly increased (p < .05) throughout the storage period. The P. tetrastromatica extracts-treated fillets showed better sensory characteristics than other seaweed extracts-treated and control fillets. Results of this study suggest that ethanolic extracts (2%, w/v) of P. tetrastromatica extend the shelf life for 12 days longer than the control fillets in refrigerated conditions.

Anti-skin glycation and collagen level stimulation of brown seaweed extracts and their compositional characteristics

This study aimed to investigate anti-skin aging potential of the extracts from three Southern Australian brown seaweeds: Ecklonia radiata (ER), Cystophora moniliformis (CM), and Cystophora siliquosa (CS). These extracts and two positive controls (Aminoguanidine (AG), a drug candidate for anti-glycation, and phloroglucinol (PG)) were tested for their inhibition of glycation reaction using in vitro non-cellular bovine serum albumin (BSA)-glucose and methylglyoxal (MGO) models. The safe doses were also established by toxicity test with human skin fibroblast cell by MTT assay. Among three extracts studied, ER showed the highest toxic, but far less than both positive controls. The CM and CS extracts at 500 μg/mL showed inhibition of glycation activity, approximately 65–90 % compared to AG (15–40 %) and PG (15–20 %) at 20 μg/mL. In addition, the stimulation of collagen and elastin levels using an in vitro cell-based assay was evaluated. Relative to the control (water without samples), the CM and CS extracts at concentration greater than or equal to 250 μg/mL significantly increased the collagen levels of human skin fibroblast cells up to ∼16.5 folds, while there was no significant increase in elastin levels by most seaweed extracts. Furthermore, compositions of all extracts were characterized. Apart from high polysaccharide contents, phlorotannin which accounts for 17–23 % of CM and CS might be responsible for their anti-skin aging benefits. These findings demonstrate that the brown seaweed extracts CM and CS have high potential to be used as skin anti-aging supplements with anti-glycation and collagen stimulation benefits, worthy of further in vivo studies.

Evaluating the effectiveness of various remediation therapies on the engineering properties of oil-contaminated soils

This study was embarked upon to ascertain the effectiveness of using physical and biological remediation procedures to amend the impact of oil pollution on soil engineering properties. Soil contaminated with crude oil at a mix ratio of 20:1 (percentage by weight), was remediated with charcoal (C2), charcoal + seaweed extract + groundnut plant (C3), and charcoal + wood ash + groundnut plant (C4). During the procedure, the soil’s total petroleum hydrocarbon (TPH) level was determined through American Public Health Association (APHA) approved procedures; while the geotechnical (maximum dry density “MDD”, optimal moisture content “OMC, and California bearing ratio “CBR”) and electrical properties (electrical conductivity “EC”, dielectric constant “ɛʹ, and electrical resistivity “ρ”) were measured in accordance with American Society for Testing and Materials (ASTM) and Institute of Electrical and Electronics Engineers (IEEE) approved procedures. The results depicted that the TPH, ɛʹ and ρ-values of the contaminated soil samples declined by 56.71%, 82.01% and 72.80%; 31.65%, 36.85% and 19.92%; and 56.32%, 62.03% and 60.27%, respectively in the C2, C3 and C4 samples after the remediation program; while the soil EC increased by 103.45%, 145.68% and 135.34% in the C2, C3 and C4 samples, respectively. Likewise, the C2, C3 and C4 samples CBR, MDD and OMC values increased by 29.49%, 34.75% and 50.30%; 7.87%, 11.02% and 4.72; and 12.02%, 28.01% and 40.38%, respectively at the end of the experimental period. These findings portrayed that hybridized remediation therapies are better remediating techniques in remediating contaminated soils; hence sustaining the integrity of the soils’ geotechnical and electrical properties.

Aqueous extraction of red seaweed bioactive compounds and synthesis of silver nanoparticles for agriculture applications

In this study, an aqueous extract of Gracilaria crassa and Grateloupia lithophila was used for the green synthesis of silver nanoparticles (AgNPs) to control plant disease and support plant growth. The synthesised AgNPs were characterised using a UV–visible spectrophotometer, FTIR, XRD, SEM, EDAX, TEM and DLS analysis. The TEM image revealed that synthesised nanoparticles with average size of 51 nm and 20 nm were observed in G. crassa and Grateloupia lithophila extract, respectively. The green synthesised AgNPs exhibited a strong antibacterial activity against Xanthomonas axonopodis pv. citri and Xanthomonas oryzae pv. oryzae, and investigated the effect of biogenic AgNPs on seed germination and seedling growth of rice plants (Oryzae sativa L). Both the sizes (51 and 20 nm) of AgNPs treatments (50 μg/ml conc.) resulted in the highest seed germination rate (98 and 99%), longer roots (17.51 ± 0.50 and 17.68 ± 0.10 cm) and shoot lengths (5.68 ± 0.12 and 6.18 ± 0.10 cm), and produced higher amount of fresh (8.98 ± 0.34 and 9.00 ± 0.14 mg) and dry (3.68 ± 0.05 and 3.80 ± 0.12 mg) biomass weights. On the other hand, rice seedlings treated with both sizes of AgNPs, particularly at 100 μg/ml concentration, responded with a lower rate of seed germination, shorter root and shoot length and a lower amount of fresh and dry biomass weight was observed. The nanocomposites synthesised from Grateloupia lithophila (20 nm) were more effective in seed germination and seedling growth than G. crassa (51 nm) nanocomposites. In this study, one-step synthesised AgNPs from red seaweeds extracts controlled the bacterial pathogens causing disease in rice and promoted the growth of the plant.