Red Seaweed Kappaphycus Research Articles

A red seaweed Kappaphycus alvarezii-based biostimulant (AgroGain®) improves the growth of Zea mays and impacts agricultural sustainability by beneficially priming rhizosphere soil microbial community.

The overuse of chemical-based agricultural inputs has led to the degradation of soil with associated adverse effects on soil attributes and microbial population. This scenario leads to poor soil health and is reportedly on the rise globally. Additionally, chemical fertilizers pose serious risks to the ecosystem and human health. In this study, foliar sprays of biostimulant (AgroGain/LBS6) prepared from the cultivated, tropical red seaweed Kappaphycus alvarezii increased the phenotypic growth of Zea mays in terms of greater leaf area, total plant height, and shoot fresh and dry weights. In addition, LBS6 improved the accumulation of chlorophyll a and b, total carotenoids, total soluble sugars, amino acids, flavonoids, and phenolics in the treated plants. LBS6 applications also improved the total bacterial and fungal count in rhizospheric soil. The V3-V4 region of 16S rRNA gene from the soil metagenome was analyzed to study the abundance of bacterial communities which were increased in the rhizosphere of LBS6-treated plants. Treatments were found to enrich beneficial soil bacteria, i.e., Proteobacteria, especially the classes Alphaproteobacteria, Cyanobacteria, Firmicutes, Actinobacteriota, Verrucomicrobiota, Chloroflexi, and Acidobacteriota and several other phyla related to plant growth promotion. A metagenomic study of those soil samples from LBS6-sprayed plants was correlated with functional potential of soil microbiota. Enrichment of metabolisms such as nitrogen, sulfur, phosphorous, plant defense, amino acid, co-factors, and vitamins was observed in soils grown with LBS6-sprayed plants. These results were further confirmed by a significant increase in the activity of soil enzymes such as urease, acid phosphatase, FDAse, dehydrogenase, catalase, and biological index of fertility in the rhizosphere of LBS6-treated corn plant. These findings conclude that the foliar application of LBS6 on Z. mays improves and recruits beneficial microbes and alters soil ecology in a sustainable manner.

Development of Gluten-Free Bread from Brown Rice-Potato Starch Composite Flour Incorporated with Red Seaweed Kappaphycus alvarezii powder

Gluten free diets and lifestyles are rapidly increasing in popularity mainly due to the increase in consumer awareness about gluten related disorders and gluten intolerances. With increasing demand, the food industry strives to develop new food products that are gluten-free and able to be consumed by those who suffer from these conditions. The objective of this study was to develop a gluten-free bread from brown rice-potato starch composite flour incorporated with red seaweed Kappaphycus alvarezii (KA) powder. KA powder, ranging from 2% to 10%, was added, and the physical properties of the gluten- free bread were assessed. Sensory evaluation was conducted using two methods, the descriptive and hedonic tests. The amount of seaweed significantly (p<0.05) influenced the loaf volume, with F5 (10%), the highest concentration of seaweed, having the highest reduction of volume of 15.38% compared to the control F0 (without seaweed). With increasing seaweed concentration, the brightness and yellowness of each bread decreased. The texture profiles of KA-incorporated bread formulations were also affected with the firmness of bread being the most significant change. The descriptive test showed that F5 (10%) had the highest intensity of seaweed effect which affected the colour, texture, aroma, taste and aftertaste of the bread. The hedonic test showed that the most acceptable formulation was F1 (2%). From these formulations, the best formulation F1 (2%) was chosen for further nutrient analysis where it was compared to the control (without seaweed). It was shown that F1 had significantly (p<0.05) higher moisture, ash, fat, and dietary fibre content, but lower carbohydrate and protein content compared to F0 (without seaweed). In conclusion, the formulation of gluten-free KA- incorporated brown rice-potato starch bread had an impact on the bread texture, colour, volume, and nutrient content.

Assessment of regulatory compounds in commercial red seaweed Kappaphycus alvarezii after long-distance transportation

Assessment of regulatory compounds in commercial red seaweed Kappaphycus alvarezii after long-distance transportation

A biostimulant prepared from red seaweed Kappaphycus alvarezii induces flowering and improves the growth of Pisum sativum grown under optimum and nitrogen-limited conditions.

Nitrogen (N) is one of the critical elements required by plants and is therefore one of the important limiting factors for growth and yield. To increase agricultural productivity, farmers are using excessive N fertilizers to the soil, which poses a threat to the ecosystem, as most of the applied nitrogen fertilizer is not taken up by crops, and runoff to aquatic bodies and the environment causes eutrophication, pollution, and greenhouse gas emissions. In this study, we used LBS6, a Kappaphycus alvarezii-based biostimulant as a sustainable alternative to improve the growth of plants under different NO3 - fertigation. A root drench treatment of 1 ml/L LBS6 significantly improved the growth of Pisum sativum plants grown under optimum and deficient N conditions. No significant difference was observed in the growth of LBS6-treated plants grown with excessive N. The application of LBS6 induced flowering under optimum and deficient N conditions. The total nitrogen, nitrate and ammonia contents of tissues were found to be higher in treated plants grown under N deficient conditions. The LBS6 treatments had significantly higher chlorophyll content in those plants grown under N-deficient conditions. The root drench application of LBS6 also regulated photosynthetic efficiency by modulating electron and proton transport-related processes of leaves in the light-adapted state. The rate of linear electron flux, proton conductivity and steady-state proton flux across the thylakoid membrane were found to be higher in LBS6-treated plants. Additionally, LBS6 also reduced nitrogen starvation-induced, reactive oxygen species accumulation by reduction in lipid peroxidation in treated plants. Gene expression analysis showed differential regulation of expression of those genes involved in N uptake, transport, assimilation, and remobilization in LBS6-treated plants. Taken together, LBS6 improved growth of those treated plants under optimum and nitrogen-limited condition by positively modulating their biochemical, molecular, and physiological processes.

Interaction of nutrient enrichment and farming method on performance of the red seaweed Kappaphycus alvarezii

To meet the increasing demand for kappa carrageenan, several strategies have been employed to improve eucheumatoid seaweed productivity, such as nutrient enrichment (NE) and the application of some efficient farming methods (FM). This study aims to investigate the interaction of NE (applied as ammonium phosphate at 3.5 g L−1) and farming method on the performance of the eucheumatoid seaweed Kappaphycus alvarezii. Three farming methods, that is, Sway (SW), Spring (SP), and modified fixed-off bottom (MFOB), were employed for nutrient-enriched (NE) and non-enriched control fronds for a period of 45 days. NE significantly improved the growth and carrageenan yield of the seaweed and afforded protection against the incidence of ice-ice disease; meanwhile, the effect of FM and NE-FM interaction was non-significant. NE increased the gel strength of the extracted carrageenan; meanwhile, SP farm led to the highest gel strength, followed by MFOB.

Molecular docking approaches of biomolecules extracted from red seaweed Kappaphycus alvarezii against hemolysin protein of bioluminescence disease-causing bacteria Vibrio harveyi

Shrimp culture systems are being affected by bacterial diseases particularly Vibrios. Use of therapeutic agents in shrimp culture has lead to the resistance among aquatic bacteria. Accordingly, health management becomes of major importance in aquaculture. Under this situation, developing bio-inhibitors from natural marine resources which are most appropriate, which is considered as an unmatched reservoir of several biological products. Molecular docking is suited to a major approach in structural biology and computer-assisted drug design against the proteins of disease-causative agents. In the present study, marine macroalga Kappaphycus alvarezii was used for developing inhibitors against bioluminescence disease-causing pathogenic bacteria Vibrio harveyi. K. alvarezii was collected from the Mandapam, Tamil Nadu, India. Ethyl acetate based extract of K. alvarezii was tested against the growth and virulence factors of V. harveyi during Penaeus monodon larviculture. Further K. alvarezii extract was subjected to GC–MS analysis to identify the biomolecules. The homology modelling of the virulent protein, hemolysin of V. harveyi was designed during this study. Hence, it was aimed at molecular docking against the biomolecules identified from K. alvarezii extract. During shrimp larviculture, the extract of K. alvarezii (200 μg mL−1) exhibited a reduction on Cumulative Percentage of Mortality (29.70 %) in postlarvae against the challenge of V. harveyi infection. Among the compounds docked, an inhibitory effect was observed based on docking scores and were found the highest binding affinity/inhibiting activity in Cyclotetracosane with the least energy required with a docking score of binding energy −7.66 kcal/mol, inhibition constant 0.002 mM and intermolecular efficiency −0.32 kcal/mol. Using statistical analysis, significant differences (p < 0.05) were observed between the growth and virulence factors of V. harveyi during shrimp larviculture trials. While considering these findings, it was determined that K. alvarezii extract can be replaced as an alternative bio-agents protecting against infections caused by V. harveyi and possibly other aquatic pathogenic bacteria in shrimp farming systems.

Potential utility of industrially unwanted constituent under the framework of waste to wealth: Edible salt from commercial marine red seaweed Kappaphycus alvarezii (Doty) L.M. Liao

Processing of 1000 kg of fresh Kappaphycus alvarezii yielded 25 kg salt. The optical microscopy revealed non-crystalline nature, absence of geometrical pattern; while squircle aggregates with ruffled surface were evident in SEM. Caenorhabditis elegans assay confirmed its non-toxicity; while absence of Salmonella and pesticides make it safe for human consumption. Among the macro elements, ‘K' content was highest (3792.74 ± 541.23 mg 100 g−1) and ‘Ca’ was lowest (7.01 ± 1.32 mg 100 g−1); whereas among micro element ‘Fe’ was highest (6.52 ± 1.40 mg 100 g−1) and ‘Ni’ lowest (0.14 ± 0.01 mg 100 g−1). Chromium (11.5 μg g−1) was lower than a permissible daily dose, while other heavy metals (Mo, Cu, Co, Zn, As, Cd, Hg, and Pb) were below detectable level. PXRD revealed that it has only KCl Form I. The study suggested potential economic utility of seaweed salt under the framework of waste to wealth.

Understanding the mode of action of AgroGain®, a biostimulant derived from the red seaweed Kappaphycus alvarezii in the stimulation of cotyledon expansion and growth of Cucumis sativa (cucumber).

Seaweed-based biostimulants are sustainable agriculture inputs that are known to have a multitude of beneficial effects on plant growth and productivity. This study demonstrates that Agrogain® (Product code: LBS6), a Kappaphycus alvarezii-derived biostimulant induced the expansion of cucumber cotyledons. Seven days treatment of LBS6-supplementation showed a 29.2% increase in area of expanded cotyledons, as compared to the control. LBS6-treated cotyledons also showed higher amylase activity, suggesting starch to sucrose conversion was used efficiently as an energy source during expansion. To understand the mechanisms of LBS6-induced expansion, real time gene expression analysis was carried out. This revealed that LBS6-treated cotyledons differentially modulated the expression of genes involved in cell division, cell number, cell expansion and cell size. LBS6 treatment also differentially regulated the expression of those genes involved in auxin and cytokinin metabolism. Further, foliar application of LBS6 on cucumber plants being grown under hydroponic conditions showed improved plant growth as compared to the control. The total leaf area of LBS6-sprayed plants increased by 19.1%, as compared to control. LBS6-sprayed plants efficiently regulated photosynthetic quenching by reducing loss via non-photochemical and non-regulatory quenching. LBS6 applications also modulated changes in the steady-state photosynthetic parameters of the cucumber leaves. It was demonstrated that LBS6 treatment modulated the electron and proton transport related pathways which help plants to efficiently utilize the photosynthetic radiation for optimal growth. These results provide clear evidence that bioactive compounds present in LBS6 improved the growth of cucumber plants by regulating the physiological as well as developmental pathways.

Application of brown seaweed-derived agro biostimulant to the commercial farming of the red seaweed Kappaphycus alvarezii in India: Growth enhancement and production of quality raw material

Currently global seaweed industries are facing issue with availability of raw material for processing of carrageenan due to low growth of current planting material. Use of biostimulants in seaweed cultivation is recently paid more attention due to their proven biostimulatory effect, of which, Ascophyllum marine plant extract powder (AMPEP) is a well proven biostimulant to improve the growth and quality of Kappaphycus alvarezii biomass. Hence, 500 kg of AMPEP was purchased and studied its impact on the commercial farming of K. alvarezii from April 2018 to January 2022 in India. Vegetative propagule of K. alvarezii were dipped in an AMPEP with concentration range of: 0.025, 0.05, 0.10, 0.15, 0.20 and 0.25 % for 30, 60, 90 and 120 min. Before out-planting on rafts in shallow coastal water and found that K. alvarezii responded well to a 0.1 % solution with dipping time of 60 min. The percentage of average daily growth rate (ADGR%) of AMPEP-treated plant in a 45 d grow out period was 3.50 ± 0.50 % vs a control of 1.75 ± 0.25 % for the summer and pre-monsoon months (p < 0.05) but no statistically significant differences between the treated and control plants were found during the rainy and winter seasons. Treated plants were found with low incidence of epiphytes, and disease as compared to control plants. The general appearance and health of treated Kappaphycus was good with significant differences in the yield and quality of semi-refined carrageenan (SRC) and dry weed quality (p < 0.05). The cost of AMPEP for producing of additional 1 kg of dry Kappaphycus was 0.066USD. Results of the present study is very encouraging and AMPEP can be used for the production of K. alvarezii biomass for industrial and biorefinery processing as it has been witnessed that there was 16.66 % increase in biomass production in 2021in India.

Use of Brown Seaweed Extracts as Bio-fertilizers and their Effects on the Carrageenan Yield, Ice-ice Disease Occurrence, and Growth Rate of the Red Seaweed Kappaphycus striatus

Kappaphycus striatus is one of the most important eucheumatoid species that is widely farmed worldwide. In the southern Philippines, where the initial farm was established, sluggish growth of farmed Kappaphycus species brought about by the poor quality of planting materials and extensive farming resulting in unproductive farms and frequent ice-ice outbreaks have been a hindrance in increasing the seaweed production. As a result, farmers have led to the application of inorganic fertilizers as nutrient enrichment for Kappaphycus. However, inorganic or chemical fertilizers always pose negative impacts on the environment. Hence, in this study, a preliminary investigation on the potential use of extracts of brown seaweeds Sargassum cristaefolium and Turbinaria conoides as bio-fertilizers was tested on K. striatus for their growth rate, carrageenan yield, and ice-ice disease occurrence. Seaweed liquid extracts (SLE): S. cristaefolium (SC), T. conoides (TC), combination of SC and TC (MX), and control (C) were utilized as bio-fertilizers for K. striatus. SLE-enriched K. striatus seedlings were cultivated in a seaweed farm using the fixed-off bottom method for 45 days. Results revealed that the specific growth rates of all SLE treatments were significantly higher than no SLE treatment at day 45. The percentage of ice-ice disease and the yield of carrageenan did not differ among treatments. Enrichment of K. striatus using SLE of two selected brown seaweeds before out-planting could improve growth rates while not affecting the ice-ice disease occurrence and carrageenan yield. Hence, formulated SLE from brown seaweeds S. cristaefolium and T. conoides can be used as potential bio-fertilizers for Kappaphycus cultivation.

Effects of selected environmental conditions on growth and carrageenan quality of laboratory-cultured Kappaphycus alvarezii (Rhodophyta) in Fiji, South Pacific

The impacts of environmental conditions (temperature, salinity, and nutrients) on growth, semi-refined carrageenan yield, gel strengths, and viscosity were assessed on the red seaweed Kappaphycus alvarezii in laboratory culture. Results showed that K. alvarezii had a higher daily growth rate (0.94% day-1) at higher temperature (30 °C). Its semi-refined carrageenan yield was high (75.79%) at a combination of low salinity (25 ppt) and high temperature (30 °C). Conversely, gel strengths made out of semi-refined carrageenan from K. alvarezii cultured at low temperature (24 °C) demonstrated a higher compression (5.84 N) and high penetration strength (0.29 N). Highest viscosity (289.50 cP) was attained at a combination of high temperature, low salinity, and high nutrient concentration. Gels made from carrageenan of K. alvarezii grown in a higher temperature (30 °C) mixed with pineapple juice showed higher compression strength demonstrating that carrageenan extracted from cultured K. alvarezii is a good thickening agent for fruit jellies or similar food products that do not require refrigeration. This could benefit communities in rural, non-electrified communities/areas of Fiji and other South Pacific Islands that could use K. alvarezii as an alternative gelling agent in the making of food products contributing towards their food and economic security.

Influence of different concentrations of ammonium phosphate on nitrogen assimilation of red seaweed Kappaphycus striatus

Eucheumatoid farming is among the most popular source of livelihood for coastal dwellers, especially in the southern Philippines. Kappaphycus and Eucheuma are the two major cultured eucheumatoid species. However, seaweed farmers have been experiencing low seaweed production for the past years. The slow growth of Kappaphycus spp. in the farm is linked to extensive farming, causing nutrient depletion in the seawater. Hence, seaweed farmers in the province of Tawi-Tawi, southern Philippines, enrich their seaweeds, Kappaphycus striatus, with a wide range of inorganic nutrient solution concentrations with an average of nearly 9 g L⁻¹. To provide standard concentration (g L⁻¹) of inorganic nutrient solution for soaking before farming the seaweed, this study investigated nitrogen assimilation using the Kjeldahl method. Treatments were the concentrations of commonly used inorganic fertilizer [ammonium phosphate, (NH4)3PO4] dissolved in filtered seawater namely; T1 = 0 g L⁻¹ as control, T2 = 3 g L⁻¹, T3 = 6 g L⁻¹, and T4 = 9 g L⁻¹. Results showed that the total nitrogen (%) of T4 (0.68±0.01) and T3 (0.59±0.07) were significantly higher (p<0.05) than T2 (0.48±0.02) and T1 (0.46±0.02). This suggests that using inorganic nutrients as enrichment to K. striatus at a concentration of 6 or 9 g L⁻¹ is effective for obtaining high nitrogen assimilation. Therefore, considering the cost-effective inorganic nutrient enrichment practice, this study recommends using 6 g L⁻¹ of inorganic nutrient concentration to help seaweed farmers boost production by improving the growth performance of K. striatus, especially when planted in nutrient-depleted farms.

Seaweed Aquaculture in Indonesia Contributes to Social and Economic Aspects of Livelihoods and Community Wellbeing

Seaweed farming in Indonesia is carried out throughout much of the archipelago and is mainly undertaken by smallholder farmers. Indonesia is the largest global producer of the red seaweeds Kappaphycus and Eucheuma, which are used to produce carrageenan, and is a major producer of Gracilaria, which is used to produce agar. Seaweed farming is attractive to farmers in rural coastal communities because capital and operating costs are low, farming techniques are not technically demanding, labour requirements are relatively low (allowing farmers to engage in other livelihoods), and production cycles are short (30–45 days), providing regular income. Using reported values for seaweed-farming income, we conclude that seaweed farming can, but does not always, lift rural households above the Indonesian poverty line. In addition to direct financial benefits, seaweed farming also contributes to human and social capital within seaweed farming households and communities. Achieving continued economic and social benefits from seaweed farming will require additional policy development, as well as research and development to support improved and more consistent seaweed productivity and improved product quality at the farm level, provision of effective extension and technical support services, and diversification of the existing value chains in order to reduce the impacts of price fluctuations that are associated with limited global commodity chains.

The Effect of Feed Supplementation with Fermented Red Seaweed (Kappaphycus alvarezii) on Growth and Survival of White Shrimp (Litopenaeus vannamei) Post-Larvae Culture

This study was aimed to investigate the effect of novel shrimp diet supplemention with fermented red seaweed Kappaphycus alvarezii on growth and survival of whiteleg shrimp (Litopenaeus vannamei) post-larvae culture. The research consisted of three consecutive steps: (1) preliminary study on Kappaphycus alvarezii fermentation, (2) feed formulation and proximate analysis, (3) performance test of commercial feed (C), commercial + 0.5% K. alvarezii (EF1), and commercial + 1.5% fermented K. alvarezii (EF2). Following 15 days of feeding, the highest biomass, specific growth rate and survival were achieved in EF2 treatment (1.60±0.21 g, 10.88±0.86%/d, 91.67±1.53%), significantly different from control (0.99±0.09 g, 7.72±0.63%/d, 47.00±5.00%) (p&lt;0.05). Overall, this study suggested that the dietary supplementation of 1.5% fermented K. alvarezii can enhance the growth and survival of whiteleg shrimp during the nursery phase.

A sulfated polysaccharide κ-carrageenan induced antioxidant defense and proteomic changes in chloroplast against leaf spot disease of tomato

Ecofriendly approaches to control plant diseases using biopolymers are gaining momentum due to their non-toxic nature to the environment. The present study elucidates the potency of a sulfated polysaccharide, κ-carrageenan, obtained from the red seaweed Kappaphycus alvarezii, as an inducer of antioxidant defense and also chloroplast proteome against leaf spot disease in tomato. к-carrageenan (0.3%) treatment was very effective in reducing disease scores in tomato plants. Fluorescent microscopy of tomato leaves stained with Uvitex 2B (a chitin specific stain) revealed that foliar application of κ-carrageenan (0.3%) reduced colonization of the pathogen Septoria lycopersici. In addition, κ-carrageenan pretreatment followed by pathogen infection recorded a higher accumulation of calcium oxalate crystals. The treatment of κ-carrageenan resulted in the induction of H2O2 and superoxide anion compared to control or S. lycopersici-infected plants. The tomato leaves treated with κ-carrageenan showed higher activity of peroxidase enzyme. Furthermore, chloroplast proteome analysis by 2D-PAGE of control, S. lycopersici-infected, κ-carrageenan-treated, and к-carrageenan treatment followed by S. lycopersici-infected leaves of tomato showed differential expression of 31 proteins, of which 11 proteins were upregulated including acid phosphatase 1-like, C- terminal processing peptidase, GATA transcription factor 5, Calvin cycle protein CP12-1, Photosystem I reaction center subunit PSAK, and subunit of cytochrome B6-F complex iron-sulfur centers. These results indicated that κ-carrageenan could be a promising inducer of antioxidant defense and modulator of chloroplast proteome in tomato plants.

Cultivation of the red seaweed Kappaphycus alvarezii using biofloc effluent

The aim of this work was to evaluate the use of effluent from a Biofloc System (BFT) as a fertilizer for the red seaweed Kappaphycus alvarezii cultivated in tanks and analyze its influence on carrageenan yield and quality. Firstly, the optimum effluent concentration and period for enrichment were determined by an in vitro study. The seedlings were then cultivated for 7 days in two different culture media: 50% von Stosch solution (V) and 25% BFT (B), both diluted in sterilized seawater. Seaweeds cultivated only in sterilized seawater were used as a control (C). After this period, all plants were grown in only sterilized seawater for a further 28 days. Seedlings from V (1.05 ± 0.02% day−1) and B (1.13 ± 0.01% day−1) showed no significant differences in growth rates, being both higher than the control (0.91 ± 0.06% day−1). Seedlings from V and B also removed a greater quantity of nitrate (58.39% and 22.97%, respectively). Seedlings from V removed 100% phosphate, while those from B removed 83.58%. The tissue nitrogen content was higher only in the V. Although no significant differences were observed among treatments in the carrageenan yield, significantly higher gel strength and viscosity were observed in B (248.85 g cm−2 and 19.89 mPa s, respectively). According to the results, BFT effluent can be used to replace von Stosch solution to grow K. alvarezii in tanks. At the same time, the seaweed, together with bacteria and microalgae from the effluent, can be an effective biofilter in IMTA systems using bioflocs.

Enhancement of Galactose Uptake from Kappaphycus alvarezii Using Saccharomyces cerevisiae through Deletion of Negative Regulators of GAL Genes

This study was aimed at enhancing galactose consumption from the red seaweed Kappaphycus alvarezii. The optimal pretreatment condition of thermal acid hydrolysis was treated with 350mM HNO3 for 60min at 121°C. The enzymatic saccharification with a 1:1 mixture of Celluclast 1.5L and Viscozyme L showed the maximum yield of glucose; 42-g/L monosaccharide concentration was obtained with the highest yield of pretreatment and enzymatic saccharification (EPS) and the lowest inhibitory compound concentration. The deletion of the GAL80, MIG1, CYC8, or TUP1 gene was performed to improve the galactose consumption rate. The strains with the deletion of the MIG1 gene (mig1Δ) showed higher galactose consumption rate and ethanol yield than other strains. High transcription levels of regulatory genes revealed that the mig1Δ relieved glucose repression. These results show that the mig1Δ enhances galactose consumption rate from K. alvarezii.

Utilization of Double Fungal Treatment by Trichoderma harzianum and Saccharomycopsis fibuligera to produce biosugar from red seaweed Kappaphycus alvarezii

Kappaphycus alvarezii is one of the natural resources that contains high carbohydrates and has the potential as an alternative raw material for the sugar industry. The aims of this research is to analyze the optimal conditions of the combination of Trichoderma harzianum and Saccharomycopsis fibuligera in degrading polysaccharides from K. alvarezii into sugar. T. harzianum and S. fibuligera were activated three times at 30° C in 2% seaweed substrate. The method used was a combination of hydrolysis and fermentation to produce evaluated bio sugar in various concentrations of inoculum (5%, 10%, 15%, and 20%) and time (0 hour, 24 hours, 48 hours, and 72 hours). Based on the results, hydrolysis with an inoculum concentration of 20% for 24 hours showed the highest total sugar production. Followed by fermentation with S. fibuligera which produced glucose and galactose which is 1.74 g/L and 9.93 g/L. In conclusion, this research demonstrates the ability of T.harzianum and S. fibuligera to convert carbohydrates from K. alvarezii to produce biosugar through a combination of hydrolysis and fermentation methods.

Studies on the development and characterization of bioplastic film from the red seaweed (Kappaphycus alvarezii).

Seaweeds rich in polysaccharides are considered commercially important because of their wide range of industrial applications. In this study, the red seaweed Kappaphycus alvarezii was used for bioplastic film production. Plasticizer polyethylene glycol (PEG) to seaweed biomass ratio was optimized and a thin bioplastic film with higher tensile strength was produced. The films obtained were characterized by its thickness, tensile strength, colour (L, a, b), elongation at break (EAB), water vapour transmission rate (WVTR) and oxygen transmission rate (OTR). TG-DSC, AFM, SEM and FTIR spectroscopy analysis were performed to assess the composition, phase transitions and chemical reaction capabilities of the film. The bioplastic film obtained from 4% K. alvarezii (whole seaweed) showed better physical and mechanical properties, whereas TG-DSC, FTIR and AFM showed similar kind of bioplastic properties in all the concentrations. Decrease in OTR was observed against decreasing wall thickness of the film. The present study suggests that the seaweed would be a potential alternate source for bioplastic production which may reduce the usage of non-degradable plastics.

Addition of carbon dioxide, followed by irradiance increase, as optimization strategy for the cultivation of the red seaweed Kappaphycus alvarezii

This work aimed to verify the effects of adding CO2 and irradiance to Kappaphycus alvarezii cultivation. Thalli were cultured in vitro for 2 weeks under low irradiance (50 μmol photons m−2 s−1) with the addition of CO2 according to the following concentrations: 142× 103 ppm (1CO2, 0.1 L min−1), 285 × 103 ppm (2CO2, 0.2 L min−1) and 428 × 103 ppm (3CO2, 0.3 L min−1), followed by culture under higher irradiance (200 μmol photons m−2 s−1) for 2 more weeks. Control had no CO2 addition. Afterwards, growth rate, chlorophyll a and carotenoid content were quantified. Samples were submitted to light microscopy and transmission electron microscopy. Growth rates of different treatments or control between experimental periods showed no significant differences, except for 2CO2 treatment at the end of each period. Kappaphycus alvarezii cultivated with CO2 addition showed cell wall thickening and increasing quantity of starch granules, chlorophyll a and carotenoids compared with control. Exposed to high irradiance, control samples showed signs of stress, such as changes in chloroplast, starch granules quantity decrease and total chlorophyll a and carotenoids increase. Samples cultivated with CO2 showed an increase in the quantity and size of the starch granules and an increase in the number of organelles (mitochondria) related to energy generation and cell construction (Golgi complex). Such alterations suggest cellular response after CO2 addition, such as the formation of starch reserves and cell wall thickening, which could make plants more tolerant to environmental stress during transport from indoor condition to sea farms.