Gracilaria Verrucosa Research Articles

Alleviating effects of Gracilaria verrucosa supplement on non-specific immunity, antioxidant capacity and immune-related genes of pacific white shrimp (Litopenaeus vannamei) provoked with white spot syndrome virus

Our work evaluated the possible underlying roles of dietary dried seaweed (Gracilaria verrucosa; GV) on the inherent immune response, antioxidant capacity, immune-related gene expression, and protection of whiteleg shrimp (Litopenaeus vannamei) contra white spot syndrome virus (WSSV). Three hundred and sixty healthy L. vannamei (15.26 g ± 1.29 g) were graded into four supplemental groups ( Triplicate/group) and fed with diets including 0 (control), 2, 4, and 8 g GV (kg diet) −1 for 21 days. Following the feeding period, each group of shrimp received an intramuscular WSSV injection (1.4 × 106 copies/ml). Hemolymph and gills samples were collected before and after the challenge with WSSV. Notably, the administration of dietary GV significantly enhanced the innate immune parameters of pacific white shrimp including total hemocyte count (THC), phagocytosis, phenoloxidase activity, reactive oxygen species (ROS) production, and lysozyme activity before and after challenge with WSSV. Additionally, dietary supplementation of 4, and 8 g of GV (kg diet)−1 remarkably elevated ACP, AKP, SOD, GPx, and catalase activities along with a decrease in the MDA level in gills of shrimp before and post-WSSV challenge. In response to the GV supplement, significant upregulation of expression of ALF1, CRU1, PEN4, and CTL with downregulation of TRAF6, STAT, TLR1, and NOS genes was recorded in the gills tissue before and post-challenge with WSSV, especially at a dose of 8.0 GV g kg − 1. Dietary inoculated shrimp with GV revealed notably higher survival percentages after being challenged with WSSV. Conclusively, these data indicate that Gracilaria verrucosa can be recommended as a valuable supplemented seaweed to stimulate the innate immunity and enhance the health of Litopenaeus vannamei against viral infection.

Properties of hydrogel for adsorbent textile dye waste based cellulose-carboxymethyl sago starch

Abstract The use of a single natural polymer in hydrogel preparations is considered insufficient to produce hydrogels that are more durable, more stable, and stronger. Blends of various natural polymers can improve each sago other’s lack of physicochemical characteristics and produce new properties. This research combines two natural polymers, cellulose and starch. Cellulose isolation from Gracilaria verrucosa seaweed using acid hydrolysis and alkaline autoclaving method produced 14.01% cellulose. This study combined the results of cellulose isolation with carboxymethyl sago starch at 0.09; 0.14 and 0.24 mol/mol AGU. The isolated cellulose-carboxymethyl sago starch has the potential as a hydrogel material with the addition of crosslinkers such as epichlorohydrin (ECH). This study aims to synthesize hydrogels from cellulose-carboxymethyl sago starch with application as a textile dye waste absorbent with a concentration of epichlorohydrin (ECH) at 7.5%. Analysis of carboxymethyl sago starch is degrees of substitution, water-soluble index (WSI), and swelling power (SP). The hydrogel properties are characterized by the degree of swelling, degree of polymerization, FTIR, and SEM, and the hydrogel adsorption ability is characterized by adsorption efficiency using a microplate reader. The research results show that hydrogel can be synthesized optimally by adding carboxymethyl sago starch (CMSS) at 0.24 mol/mol AGU. The results of FTIR analysis are also by chemical measurements (swelling and gel fraction). In contrast, for maximum colour absorption, the addition of carboxymethyl sago starch is 0.09 mol/mol AGU for purple, yellow, and black and 0.14 mol/mol AGU for green color absorption. In conclusion, the adsorption ability of hydrogel in commercial textile dyes is maximum when the carboxymethyl sago starch (CMSS) is added at 0.09 mol/mol AGU with the best adsorption efficiency at purple 86.22%, yellow 77.40%, black 73.70% and at the addition of CMSS 0.14 mol/mol AGU the best adsorption efficiency in green is 73.46%.

Seaweed Diversity at Batu Lawang Beach, Sengkol Village, Pujut District, Central Lombok Regency

Seaweed is a marine and fisheries resource that is currently widely utilized by aquaculture communities and coastal fishermen, because in addition to being easy to maintain, it also provides economic benefits. Batu Lawang beach has the potential for natural grass resources that can be developed. This can be seen from the condition of the water quality in the waters. Some types of seaweed that are cultivated are Kappaphycus alvarezii and Eucheuma spinosum. Batu Lawang beach is an area that has a variety of macroalgae, as well as a fairly large coral reef area. Therefore, this research was carried out to find out the types of macroalgae in the Batu Lawang Beach area. The research was conducted in May-June 2024. This research location is located at Batu Lawang Beach, Gerupuk, Sengkol Village, Pujut District, Central Lombok Regency. This research used purposive sampling method. The results of this study, seaweed that grow naturally are Acanthophora spicifera, Gracilaria verrucosa, Sargassum cristaefolium, Gracilaria coronopifolia, Valoniopsis pachynema, Ulva, K. alvarezii, Halimeda opuntia, Eucheuma spinosum, Dictyopteris dichotoma, Laurencia papillosa, Codium fragile, Padina sp., Turbinaria decurrens, Halimeda tuna, Gracilaria sp. The conclusion is the is 16 types of seaweed that grow wild, with each type containing different antioxidants and chlorophyll-a.

Green Synthesis of CuO Nanoparticles from Macroalgae Ulva lactuca and Gracilaria verrucosa.

Macroalgae seaweeds such as Ulva lactuca and Gracilaria verrucosa cause problems on the northern coast of the Italian Adriatic Sea because their overabundance hinders the growth of cultivated clams, Rudatapes philippinarum. This study focused on the green synthesis of CuO nanoparticles from U. lactuca and G. verrucosa. The biosynthesized CuO NPs were successfully characterized using FTIR, XRD, HRTEM/EDX, and zeta potential. Nanoparticles from the two different algae species are essentially identical, with the same physical characteristics and almost the same antimicrobial activities. We have not investigated the cause of this identity, but it seems likely to arise from the reaction of Cu with the same algae metabolites in both species. The study demonstrates that it is possible to obtain useful products from these macroalgae through a green synthesis approach and that they should be considered as not just a cause of environmental and economic damage but also as a potential source of income.

The effect of substrate type composition on the growth of the seaweed Gracilaria verrucosa in controlled containers

The effect of substrate type composition on the growth of the seaweed Gracilaria verrucosa in controlled containers

Identifying the Environmental Factors that Determine the Agar Content of Seaweed <i>Gracilaria verrucosa</i> in Acid Sulfate Soil-Affected Brackishwater Ponds

Identifying the Environmental Factors that Determine the Agar Content of Seaweed <i>Gracilaria verrucosa</i> in Acid Sulfate Soil-Affected Brackishwater Ponds

Production of levulinic acid from macroalgae by hydrothermal conversion with ionic resin catalyst

Gracilaria verrucosa is red algae (Rhodophyta) that is particularly significant because of its potential for bioenergy production as a sustainable and environmentally friendly marine bioresource. This study focuses on the production of levulinic acid from G. verrucosa using hydrothermal conversion with an ionic resin Purolite CT269DR as the catalyst. By optimization of the conversion condition, a 30.3 % (22.58 g/L) yield of levulinic acid (LA) (based on carbohydrate content) was obtained at 200 °C for 90 min with 12.5 % biomass and 50 % catalyst loading of biomass quantity. Simultaneously, formic acid yielded 14.0 % (10.42 g/L). The LA yield increased with increasing combined severity (CS) levels under tested ranges. Furthermore, the relationship between CS and LA synthesis was effectively fitted to the nonlinear sigmoidal equation. However, as the yield of sugar decreased, LA yield was linearly increased. Thus, the use of ionic resin as a heterogeneous catalyst presents significant potential for the manufacture of platform chemicals, specifically LA, through the conversion of renewable marine macroalgae.

Algal biomass-based zero-waste biorefinery for producing optically pure (R)-γ-valerolactone and carbonaceous electrodes applicable for energy storage devices

Mankind is facing a severe climate crisis caused by fossil fuel-derived CO2 emissions. Although biorefineries utilizing biomass have been considered the best option for carbon-neutrality, most biorefinery-derived products have not yet been promising for economic feasibility; various strategies have been developed to increase economic competitiveness, and zero-waste biorefineries are challenging options. Herein, we aim to develop an algal biomass-based zero-waste biorefinery for producing enantioselective (R)-γ-valerolactone ((R)-GVL) and carbonaceous electrodes applicable for Li-ion batteries (LiBs). Various algal biomasses were hydrothermally oxidized to produce levulinic acid (LA) as an intermediate for producing (R)-GVL, resulting that Gracilaria verrucosa was selected as feedstock. For the hydroxylation of G. verrucosa-derived LA to 4-hydroxyvaleric acid (4-HV), 3-hydroxybutyrate dehydrogenase (HBDH) was explored through genome mining and further engineered. The engineered HBDH successfully converted G. verrucosa-derived LA to 4-HV, which was subsequently lactonized under acidic conditions, resulting in optically pure (R)-GVL. To our knowledge, this is the first report of the production of an algal biomass-derived enantioselective (R)-GVL with a perfect enantiomeric excess (>99.99 %) that can be used as a precursor for more valuable biopharmaceuticals and bioplastics than biofuels. Furthermore, residual G. verrucosa after hydrothermal oxidation was used as a carbonaceous anode material for LIBs for the first time; hard carbon anodes, which were prepared through simple heat treatment (800 ℃, 3 h, argon atmosphere), exhibit good capacities of 231, 191, 133, 108, 97 and 86 mAh/g at 0.05, 0.1, 0.5, 1, 1.5, and 2 A/g, respectively. The results discussed herein can provide insights into zero-waste biorefineries applicable for diverse industrial fields (e.g., biopolymer, biopharmaceutical and energy storage) and contribute to the construction of closed-carbon-loops for coping with climate change.

Tuning the extraction methodology targeting protein-enriched fractions from red algae

Alternative protein sources are being studied to substitute animal protein production and decrease the environmental issues that are inherent to the production of animal-based foods.This study investigates the potential of red macroalgae (Gracilaria verrucosa, Porphyra dioica, and Palmaria palmata) as an eco-friendly alternative protein source. Using the Osborne fractionation methodology, proteins were extracted under varying parameters (pH and grinding) and techniques (ultrasound and enzymatic extractions). Seaweed proteins exhibited a strong affinity for water and alkaline environments. Optimal extraction yields were obtained with H2O for G. verrucosa (33.24 ± 1.81 g protein/100 g algae protein) and P. palmata (29.56 ± 1.73 gprotein/100 galgae protein), while P. dioica showed highest yields with aqueous 0.1 M NaOH (26.28 ± 5.90 gprotein/100 galgae protein). Molecular weight patterns revealed aggregates (> 200 kDa) in G. verrucosa and P. palmata in the 0.1 M NaOH fraction. H2O extracts displayed peaks (48–84 kDa) linked to phycobiliproteins, showcasing good emulsifying properties. Solubility varied with solvents, with saline and 70 % EtOH dissolving lower molecular weight proteins. Aqueous 0.1 M NaOH extracts demonstrated promising texturizing capacity.Overall, proteins from red macroalgae show potential for food product development, offering an alternative with lower environmental impact compared to conventional animal-based proteins.

Physicochemical Properties of Restructured Black Goat Jerky with Various Types of Ultra-Ground Seaweed Powders.

This study investigated the effects of ultra-ground seaweed powders (USP) on the physicochemical properties (proximate composition, mineral contents, pH, color, shear force, sensory evaluation, electronic nose, and electronic tongue) of restructured black goat jerky. Restructured black goat jerky was prepared using three different treatments, i.e., 3% (w/w) each of ultra-ground sea tangle (ST; Undaria pinnatifida), sea mustard (SM; Saccharina japonica), and sea string (SS; Gracilaria verrucosa) powders. Moisture and ash contents were significantly higher in the USP-treated group than in the control (p<0.05). Potassium, calcium, and zinc contents were significantly higher in the SM than in the other USP-treated groups (p<0.05). In contrast, pH values were significantly higher in the ST and SM than in the control and SS (p<0.05). CIE L*, CIE a*, CIE b*, and shear force were significantly lower in the USP-treated groups than in the control (p<0.05). Sensory evaluation revealed no significant difference in taste, texture, seaweed-like odor, and goaty flavor (p<0.05). Principal component analysis (PCA) and peak graph analysis of the electronic nose showed that the SS differed the most from the control compared with the other USP-treated groups, owing to the seaweed odor of ultra-ground SS powder. The PCA and ranking analysis of the electronic tongue showed that the umami taste of the SM was higher than that of the control and other USP-treated groups. Therefore, the potassium, calcium, zinc contents, and umami taste of reconstituted black goat jerky were significantly higher in the SM than in the control and other USP-treated groups.

Characterization of red algae (Gracilaria verrucosa) on potential application for topical treatment of oral mucosa wounds in Rattus norvegicus.

Wound healing in the mouth has its challenges due to masticatory movements and the presence of bacteria that can inhibit its process. The aim of this study was to analyze the contents of red algae (Gracilaria verrucosa) from Indonesia, and its potential as a wound-healing agent for oral wounds using animal model. Red algae content was determined by phytochemical tests and gas chromatography-mass spectroscopy (GC-MS). The wound was made by making an incision on the gingival mucosa of Rattus norvegicus and the parameters assessed were bleeding time, number of fibroblast cells, and time of wound closure. Three doses of G. verrucosa gel were used (2.5%, 5%, and 10%) and the gels were applied twice a day, at 6:00 and 18:00. Application was carried out topically by applying 0.1 ml of gel to the incision wound using a 1 mL syringe. Our phytochemical test indicated that the G. verrucosa contained alkaloids, steroids, flavonoids, and phenols. The dominant contains of the G. verrucosa were glycerol (36.81%), hexadecenoic acid (20.74%), and cholesterol (7.4%). The hemostasis test showed that the 2.5% G. verrucosa extract gel had the shortest bleeding time, 33.98±2.66 seconds. On the seventh day of the initial proliferation phase, the number of fibroblasts was not significantly different among groups. On day 14, the number of fibroblasts was only significantly different between 10% G. verrucosa and untreated group (p=0.007). On day 28, however, both 5% and 10% G. verrucosa were significantly higher compared to untreated group, both had p=0.010. Daily clinical examination showed that animals that were given 2.5% and 5% of G. verrucosa extract gel experienced wound closure on day 10. Animals treated with 10% of extract gel, all wounds healed on day 9. This study suggested that G. verrucosa extract could accelerate wound closure and wound healing.

Changes in the Biological Activities of Gracilaria verrucosa Extracted Using Different Extraction Solvents

This study investigated the antioxidant, antiaging, and antibacterial properties of Gracilaria verrucosa (GV) based on 95% methanol (GVM), ethanol (GVE), and hot water (GVW) extractions. Antioxidant activity assays revealed the total polyphenol and flavonoid contents were highest in GVM and GVE. The 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and 2,2′-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) activities were highest in GVE and GVM. Furthermore, GVE exhibited the highest ferric-reducing antioxidant power (FRAP) value. In comparison, superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities were highest in GVM. Collectively, GVE and GVM had stronger antioxidant activities than GVW. Additionally, collagenase, elastase, and tyrosinase inhibition assays showed that GVM exhibited the strongest anti-wrinkle and skin-whitening activities. Liquid chromatography–tandem mass spectrometer (LC–MS/MS) revealed that GVW had the highest 4-hydroxy benzoic acid content, whereas GVE had the highest naringenin and naringin contents. Additionally, GVE exhibited the strongest antimicrobial activity against six foodborne bacteria, with minimum inhibitory and bactericidal concentrations of 0.06–0.3 and 0.1–0.5 μg/μL. Correlation analysis of the GV extracts indicated a strong positive relationship between TPC and ABTS, SOD, and CAT activities (r = 0.760–0.982, p = 0–0.018). Overall, GVE and GVM can be applied to the development of functional agents across diverse industries.

Optimizaton quality of Agar Gracilaria verrucosa Seaweed with different density in extensive polyculture system

Optimizaton quality of Agar Gracilaria verrucosa Seaweed with different density in extensive polyculture system

Potential Extract Of Red Algae (Gracilaria verrucosa) from Aceh’s Coast Against Streptococcus mutans

Dental caries is a disease of hard tooth tissue which is demineralized in hard tissue due to bacterial activity that produce acid. Streptococcus mutans known as the main agent of dental caries. Gracilaria verrucosa red algae is one of many marine products of Aceh’s coast which containing antibacterial compounds such as flavonoids, tannins and phenols. The aim of this research is to know the antibacterial potency of red algae extract of Gracilaria verrucosa from Aceh’s coast towards Streptococcus mutans by observe Minimum Inhibitory Concentration (MIC) and Minimum Bactericicdal Concentration (MBC). Maceration method was used to produce extraction of Gracilaria verrucosa with 96% ethanol as solvent. The extract concentration used for this study was 20%, 40%, 60%, 80% and 100%. The results showed that the growth of S. mutans colonies had started to decrease at concentration of 20% i.e. 995.3 x 104 CFU/ml and the least colony growth occurred at concentration of 100% i.e. 54 x 104 CFU/ml. The conclusion of this research is Gracilaria verrucosa extract has antibacterial potential against S. mutans with MIC is at concentration of 20% whereas MBC is not found.

Sifat Fisik dan Organoleptik Tepung Rumput Laut Gracilaria verrucosa Dari Berbagai Penanganan

Gracilaria verrucosa one of the seaweed that is abundant but yet to be fully developed in optimum manner. This seaweed contains polysaccharides, protein, lipids, vitamins, polyphenols which can be used as nutraceutical food, besides soluble and insoluble fiber which can reduce diabetic, heart disease and cancer. This research aimed to identify various handling treatments of the physical properties and organoleptic of Gracilaria verrucosa flour. Methods used the Randomized design with 6 treatments, which are fresh seaweed, dried seaweed, dried seaweed with treatment 4% KOH and 24 hours fermented wish S.cerevisiae. The handling treatment had a significant effect except on the physical properties of color and organoleptic aroma. The best treatment was the treatment of Gracilaria verrucosa drying 10 hours + 4% KOH extraction + drying cabinet dryer) which resulted in an average moisture content of 12.48%, yield 19.175%, density 0.624%, viscosity 75.4 cps, color (L*a* b) 25.08*-4.36% 1.38, color organoleptic 5.13 (rather like) and aroma organoleptic 4.80 (ordinary-rather like).

Traditional polyculture as a mangrove restoration solution in Delta Mahakam, East Kalimantan Indonesia

The Mahakam Delta is a large mangrove ecosystem in East Kalimantan with a precious ecosystem and a massive mangrove species. Because of the conversion to shrimp aquaculture, the mangrove ecosystem has been devastated. This study looks at shrimp pond management in Salo Palai, Muara Badak, Kutai Kartanegara, East Kalimantan, using the traditional polyculture concept to increase pond productivity. The current shrimp pond condition was decreased water quality, substrate infertility, and natural food availability crisis. This model focused on traditional management, with a particular emphasis on pond preparation, polyculture, and used plant extracts. For 100 days, Penaeus monodon, Chanos chanos, Litopenaeus vannamei, Lates calcarifer, Scylla spp., and Gracilaria verrucosa were grown in the same time and pond. The yield from the pond was thrived: 332.14 kg/Ha. This concept can be used to restore mangroves, preserve the mangrove ecosystem, increase shrimp pond production, and protect the sea ecosystem; thus, this method achieves sustainable aquaculture.

Antibacterial activity of GVL,a lectin isolated from marine algae Gracilaria verrucosa

Lectins are univalent or polyvalent carbohydrate-binding proteins of non-immune origin that are widely distributed in the marine ecosystem. A lectin was isolated from marine algae Gracilaria verrucosa by G-100 gel filtration chromatography. This lectin was named GVL, agglutinated rat, rabbit, goat, chicken and human ABO erythrocytes. The antibacterial activity of this algal lectin was studied using disc diffusion method. GVL exhibited potent antibacterial activity against bacteria such as E.coli, S.pyogenes, S.aureus, E.faecalis, B.subtilis and coagulase-negative Staphylococci(CoNS) by disc diffusion method. Also, the results were compared with the standard antibiotic Ampicillin. These findings indicate that GVL is having therapeutic applications with great importance in clinical microbiology.

Metabolites Alteration and Antioxidant Activity of Gracilaria verrucosa After Fermentation Using Aureobasidium melanogenum MTGK.31

Gracilaria verrucosa is a red seaweed that has been widely utilized in the food andpharmaceutical industries due to its biological properties. The utilization of biologicalagents in obtaining certain bioactive compounds would confront unavoidable issues,particularly its bioactive sustainability. Hence, microbial fermentation has been reported as a practical approach to maintaining bioactive production and boosting its properties. Our study aimed to evaluate the potential of marine yeast Aureobasidium melanogenum MTGK.31 as a fermenting agent for G. verrucosa and characterize the seaweed metabolite profile and antioxidant activity after fermentation. The seaweed was fermented using A. melanogenum MTGK.31 in a medium consisting of yeast extract, peptone, and glucose. The fermentation was done for 24, 48, and 72 hours. Total plate count and pH were measured after each fermentation period. The primary and secondary metabolites of G. verrucosa in each fermentation were observed. Antioxidant assay using the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) method was conducted, followed by total phenolic content using the Folin-Ciocalteu method. It was highlighted that yeast colony increased during the fermentation, while the pH level was decreasing. We found that the fermentation not only boosted some elements in primary metabolites, but also increased G. verrucosa bioactive groups. After 72 hours of fermentation, the G. verrucosa percent radical scavenging activity (%RSA) increased more than two times compared to the fresh G. verrucosa with a %RSA value of 16.09±6.57. Nevertheless, the highest total phenolic content of 5.62±0.00028 mg GAE/g extract was shown by G. verrucosa after 48 hours of fermentation.

Metabolites Alteration and Antioxidant Activity of Gracilaria verrucosa After Fermentation Using Aureobasidium melanogenum MTGK.31

Gracilaria verrucosa is a red seaweed that has been widely utilized in the food and pharmaceutical industries due to its biological properties. The utilization of biological agents in obtaining certain bioactive compounds would confront unavoidable issues, particularly its bioactive sustainability. Hence, microbial fermentation has been reported as a practical approach to maintaining bioactive production and boosting its properties. Our study aimed to evaluate the potential of marine yeast Aureobasidium melanogenum MTGK.31 as a fermenting agent for G. verrucosa and characterize the seaweed metabolite profile and antioxidant activity after fermentation. The seaweed was fermented using A. melanogenum MTGK.31 in a medium consisting of yeast extract, peptone, and glucose. The fermentation was done for 24, 48, and 72 hours. Total plate count and pH were measured after each fermentation period. The primary and secondary metabolites of G. verrucosa in each fermentation were observed. Antioxidant assay using the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) method was conducted, followed by total phenolic content using the Folin-Ciocalteu method. It was highlighted that yeast colony increased during the fermentation, while the pH level was decreasing. We found that the fermentation not only boosted some elements in primary metabolites, but also increased G. verrucosa bioactive groups. After 72 hours of fermentation, the G. verrucosa percent radical scavenging activity (%RSA) increased more than two times compared to the fresh G. verrucosa with a %RSA value of 16.09±6.57. Nevertheless, the highest total phenolic content of 5.62±0.00028 mg GAE/g extract was shown by G. verrucosa after 48 hours of fermentation.

Electrical Energy Production with Microbial Fuel Cell (MFC) Technology on Gracilaria verrucosa Substrate

Microbial Fuel Cell (MFC) is a renewable technology based on electrochemistry that has the ability to convert chemical energy into electrical energy through microbial metabolic processes. This study aims to determine the effect of adding an electrolyte solution to the production of electricity generated using the substrate Gracilaria verrucosa and the microbe Saccharomyces cerevisiae. The method used in this study uses a double chamber consisting of anode and cathode chambers connected through a proton exchange membrane (PEM) in the form of Nafion 117. The results showed that the addition of 0.2 M KMnO4 electrolyte solution produced current, voltage and power density respectively. of 0.74 mA; 580 mV and 2187 mW/cm2 higher than the addition of 0.2 M K3Fe(CN)6 electrolyte solution resulted in a current, voltage and power density of 0.69 mA, respectively; 450 mV and 1582.16 mW/cm2. The MFC system using Gracilaria verrucosa as a substrate has the potential to generate electrical energy. Keywords: Microbial Fuel Cell (MFC), Electrical energy, Gracilaria verrucosa, Saccharomyces cerevisiae