Optimization of bioactive compound production from seaweed via subcritical water extraction

Seaweeds have been used for food, pharmaceutical and nutracuetical products due to its high bioactive compounds. The compounds are entrapped inside the seaweed require to be extracted out for product formulation. This study utilises Subcritical Water Extraction (SWE) technology to extract those compounds. SWE provides green extraction approach by using water as solvent, less operating time and cost effective. Three different seaweed samples were used, Brown Seaweed (Sample A) – Padina Sp., Brown Seaweed (Sample B) – Sargassum Sp., and Green Seaweed (Sample C) – Enteromorpha Sp. The reaction conditions were optimized include temperature (112.73 – 247.37 °C), reaction time (11.59 – 28.4 min) and concentration of biomass loading (6.59 – 23.41 %) for high carbohydrate and protein production. It was found that the highest carbohydrate of 31.8 w/w % was obtained by Sample C, extracting at temperature 140 °C, at 15 min of reaction time and 10 % of biomass loading. The highest protein concentration of 11.22 w/w % was achieved at temperature 220 °C, at 25 min of reaction time and 10 % of biomass loading by Sample C. Furthermore, the statistical analysis revealed that amongst the parameters investigated that temperature was the most critical factor during extraction of bioactive compounds. However, the concentration of biomass loading gave less significant effect to the carbohydrate and protein yields. Based on the findings, it was proven that the SWE has potential to be use in extractiong bioactive compounds from seaweed. However, further study on the extraction mechanism is required to understand the fundamental on the technology

Total RNA Extraction for the Red Seaweed Gracilaria changii (Gracilariales, Rhodophyta)

Five different RNA extraction methods have been tried out on the red seaweed, Gracilaria changii collected from the mangrove area at Morib, Selangor, Malaysia. Two methods, one utilising guanidinium thiocyanate, and another using cetyltrimethyl ammonium bromide (CTAB), were found to be potential alternatives to obtain pure RNA. By incorporating sand while grinding the tissue, the method using CTAB was found most suitable to obtain pure RNA (high A260:280nm ratio) with high yield (0.16ug RNA per gram of fresh tissue)

Transcripts of Gracilaria changii that improve copper tolerance of Escherichia coli

In this study, we used bacterial functional screening to isolate transcripts from a red seaweed, Gracilaria changii Abbott, Zhang et Xia (Xia et Abbott) that improved copper tolerance of Escherichia coli. We have identified several seaweed proteins that may be involved in copper efflux, detoxification and ROS scavenging, such as ATPase, outward-rectifying potassium channel (KCO1), vanadium chloroperoxidase and a high affinity phosphate transporter. All transcripts were shown to be able to enhance the copper tolerance of E. coli up to 4 mM CuCl2. These transcripts may share similar functions in the copper homeostasis of both E. coli and G. changii. In addition, we discovered a few transcripts with uncharacterized function(s) in copper tolerance in both organisms

Culture of microalgae using interstitial water extracted from shrimp pond bottom sediments

Interstitial water, extracted from the bottom sediment of a shrimp culture pond, was rich in nutrients containing total phosphorus with concentration of 25.98 mg/l and total nitrogen of 65.45 mg/l. A diatom, Chaetoceros calcitrans, a green alga, Nannochloropsis oculata, and a cyanobacterium, Oscillatoria sp., were cultured in pure interstitial water (PIW), diluted interstitial water (DIW) and in Conway medium (CM). C. calcitrans showed a significantly higher (P 0.05) in the growth rate of Oscillatoria sp. cultured in interstitial water and that with added silica or a combination of nitrogen, phosphorus and silica. This study indicates that interstitial water extracted from aquaculture ponds, in sterilized diluted form, has the potential to be used as an effective medium for the culture of microalgae. © 2001 Elsevier Science B.V. All rights reserved

Enhancement of Power Output by using Alginate Immobilized Algae in Biophotovoltaic Devices.

We report for the first time a photosynthetically active algae immobilized in alginate gel within a fuel cell design for generation of bioelectricity. The algal-alginate biofilm was utilized within a biophotovoltaics (BPV) device developed for direct bioelectricity generation from photosynthesis. A peak power output of 0.289 mWm-2 with an increase of 18% in power output compared to conventional suspension culture BPV device was observed. The increase in maximum power density was correlated to the maximum relative electron transport rate (rETRm). The semi-dry type of photosynthetically active biofilm proposed in this work may offer significantly improved performances in terms of fuel cell design, bioelectricity generation, oxygen production and CO2 reduction

A simple and effective method for RNA isolation and cDNA library construction from the brown seaweed Sargassum polycystum (Fucales, Phaeophyceae)

The isolation of high-quality RNA from brown seaweeds has always been problematic due to a high content of polyphenolic compounds and polysaccharides in their tissues. This study presents a simple and effective method for isolating high-quality RNA from the brown seaweeds Sargassum (Sargassum polycystum, Sargassum siliquosum, Sargassum baccularia, and Sargassum binderi), Padina tetrastromatica, Turbinaria conoides, Dictyota sp., and Hormophysa cuneiformis using cetyltrimethylammonium bromide and selective lithium chloride precipitation. Approximately 25–43 μg g−1 fresh weight of total RNA was obtained from these brown algae. The A 260/A 280 absorbance ratio of these RNA samples are between 1.995 ± 0.027 and 2.122 ± 0.013, with distinct 28S and 18S ribosomal RNA bands visible on a formaldehyde agarose gel. The RNA obtained from S. polycystum was found to be suitable for many downstream applications such as reverse transcription polymerase chain reaction, cloning, synthesis of cDNA, and construction of cDNA library for the generation of expressed sequence tags

Molecular differentiation of two morphological variants of gracilaria salicornia

Xia in 1986 combined Gracilaria salicornia, G. canaliculata (G. crassa), G. cacalia and G. minor into one species: G. salicornia. Two morphological variants of G. salicornia were collected from different localities in Malaysia. Variant A collected from Morib, Selangor grew on the roots of Avicennia. The samples showed absence of main axis; segmented constrictions throughout; cylindrical or slightly compressed thalli. Variant B was collected from the mudflats of Tanjung Tuan, growing on rocks, coral or forming mats on the mud. Plants showed absence of main axis; segments were not constricted throughout the plant (if present only slightly articulated at the upper part), branching was dichotomous or irregular; cylindrical or slightly compressed thalli. The technique of Random Amplified Polymorphic DNA analysis (RAPD) was used to investigate molecular characteristics of the two variants. Out of sixty Operon primers that were screened, four primers, OPA 1, OPA 10, OPA 11 and OPK 7 were able to give polymorphism. The fingerprints generated were stable and reproducible on repeated analysis. The DNA fingerprints generated were visually analysed and clustering analysis was carried out using GelCompar 4.0. The matrix of similarities was based on the Dice coefficients (SD) and the cluster analysis was carried out using the unweighted pair group method using arithmetic averages (UPGMA). DNA analysis showed that two primers (OPA 01, CAGGCCCTTC and OPK 07, AGCGAGCAAG) were able to differentiate the two variants

Agar properties of Gracilaria species (Gracilariaceae, Rhodophyta) collected from different natural habitats in Malaysia

The yield and quality of agar from Gracilaria species collected from distinct natural habitats (mangrove swamp, rocky shore, sandy mudflat) along the west coast of Peninsular Malaysia were evaluated in this study. The agar content was found to be significantly higher in G. changii and G. edulis growing in the mangrove swamp, while the lowest agar content was recorded for G. changii and G. edulis collected from the sandy mudflat. Higher agar gel strength was obtained from the three Gracilaria species collected from the mangrove swamp compared to those that live in the sandy mudflat and rocky shore. The intraspecific variations found in gelling temperature were well correlated with the trend of changes in agar gel strength, except for G. changii collected from the sandy mudflat and rocky shore. The intraspecific and interspecific variations of agar melting temperature did not show a consistent trend for all Gracilaria species tested. The agars of Gracilaria spp. collected from the rocky shore showed a significantly higher gel syneresis while the lowest gel syneresis was recorded for the agars of samples collected from the mangrove swamp, except for the agars of G. salicornia from different habitats which showed no difference. In conclusion, the mangrove swamp is a natural habitat which produces Gracilaria with good agar properties, in terms of agar yield, gel strength and gel hysteresis, thus it can be considered as a potential site for seaweed farming and mariculture for the agar industry in Malaysia

Transcriptomic analysis of Gracilaria changii (Rhodophyta) in response to hyper- and hypo-osmotic stresses

Osmotic stress is one of the most significant natural abiotic stresses that occur in the intertidal zones. Seaweeds may physiologically acclimate to changing osmolarity by altering their transcriptome. Here, we investigated the transcriptomic changes of Gracilaria changii (B. M. Xia et I. A. Abbott) I. A. Abbott, J. Zhang et B. M. Xia in response to hyper- and hypoosmotic stresses using a cDNA microarray approach. Microarray analysis revealed that 199 and 200 genes from ∼3,300 genes examined were up- and down-regulated by >2-fold in seaweed samples treated at 50 parts per thousand (ppt) artificial seawater (ASW) compared with those at 30 ppt ASW, respectively. The number of genes that were up- and down-regulated by >2-fold in seaweed samples treated at 10 ppt ASW compared with those at 30 ppt ASW were 154 and 187, respectively. A majority of these genes were only differentially expressed under hyper- or hypoosmotic conditions, whereas 67 transcripts were affected by both stresses. The findings of this study have shed light on the expression profiles of many transcripts during the acclimation of G. changii to hyperosmotic and hypoosmotic conditions. This information may assist in the prioritization of genes to be examined in future studies

Nutritional values of chironomid larvae grown in palm oil mill effluent and algal culture

Chironomid larvae were grown in nine 70-1 tanks containing palm oil mill effluent (POME) and algol culture. The algol culture was obtained by inoculating 200 ml pure culture of Chlorella vulgaris Beijerinck initially in 20-1 tap water containing inorganic fertilizer N:P:K (1:0.2:0.2). Each treatment was done in triplicate. Dissolved oxygen, pH, total nitrogen, total ammonia nitrogen, ortho-phosphate, chemical oxygen demand (COD), total suspended solids and total dissolved solids of the media in each tank were analyzed. Protein, lipid ash, amino acids, fatty acids, total carotene and minerals were determined for POME, chironomid larvae, and algae. The culture was terminated after 25 days and chironomid production was determined. The production of chironomid larvae was significantly (P < 0.01) higher in POME tanks (580 g/20 1 POME) than in algal culture (35 g/20 1 algal culture). Raw palm oil mill effluents contained significantly higher (P < 0.05) arginine, methionine, isoleucine and phenylalanine than algae grown in fertilizer. The essential amino acids of chironomid larvae grown in POME such as histidine, arginine, methionine, isoleucine, phenylalanine and lysine were significantly (P < 0.05) higher than in chironomid larvae grown on algal culture. The polyunsaturated fatty acids (PUFA) with the exception of Υ-linolenic acid (18:3n - 6), were higher in chironomid larvae grown in POME than those grown on algal culture. Twenty seven minerals were detected by electron microscope but 23 minerals were analyzed and quantified in POME, algae, and chironomid larvae grown in POME and algol culture. The quantity of sulfur was significantly higher (P < 0.05) in POME than algae, which probably induced the synthesis of methionine, a S-containing essential amino acid in chironomid larvae cultured in POME. Experiments showed that POME did not only induce high production of chironomid larvae, but also produced high quality live food for the aquaculture industry