Surface Of Seaweed Research Articles

Investigation of the adsorption affinity of organic micropollutants on seaweed and its QSAR study

Seaweed, one of the most abundant biomaterials, can be used as a biosorbent to remove organic micropollutants. In order to effectively use seaweed to remove a variety of micropollutants, it is vital to rapidly estimate the adsorption affinity according to the types of micropollutants. Thus, the isothermal adsorption affinities of 31 organic micropollutants in neutral or ionic form on seaweed were measured, and a predictive model using quantitative structure-adsorption relationship (QSAR) modeling was developed. As a result, it was found that the types of micropollutants had a significant effect on the adsorption of seaweed, as expected, and QSAR modeling with a predictability (R2) of 0.854 and a standard error (SE) of 0.27 log units using a training set could be developed. The model's predictability was internally and externally validated using leave-one-out cross validation and a test set. Its predictability for the external validation set was R2 = 0.864, SE = 0.171 log units. Using the developed model, we identified the most important driving forces of the adsorption at the molecular level: Coulomb interaction of the anion, molecular volume, and H-bond acceptor and donor, which significantly affect the basic momentum of molecules on the surface of seaweed. Moreover, in silico calculated descriptors were applied to the prediction, and the results revealed reasonable predictability (R2 of 0.944 and SE of 0.17 log units). Our approach provides an understanding of the adsorption process of seaweed for organic micropollutants and an efficient prediction method to estimate the adsorption affinities of seaweed and micropollutants in neutral and ionic forms.

Hydrolyzing Laminaria japonica with a combination of microbial alginate lyase and cellulase

A novel seaweed-hydrolyzing strain designated as Pseudoalteromonas sp. Alg6B was isolated from the surface of brown seaweed (Laminaria japonica). The activity of crude alginate lyase produced by Alg6B was 54.5 U/ml and the main products of hydrolyzing alginate were disaccharide and tetrasaccharide. The hydrolysis rate of seaweed reached up to 97% after combining 3% (v/v) Alg6B and 0.2% (w/v) solid cellulase. In kelp hydrolysate, the contents of nutrients are much more than raw seaweed. Alg6B grows quickly and has the ability of producing alginate oligosaccharides with low molecular weight (MW) (≤2 kDa). Furthermore, this study demonstrates that a combination of microbial alginate lyase and cellulase could almost hydrolyze seaweed completely. This research indicated that Alg6B could provide a feasible pathway to produce alginate oligosaccharides (AOS), and the synergistic effect of alginate lyase and cellulase on seaweed bioconversion can potentially pave the way to the sustainable production of seaweed fertilizer.

Ethanol production from Gracilaria fisheri using three marine epiphytic yeast species

Biofuels, especially bioethanol, are renewable resources that can supplement fossil fuel use. Gracilaria fisheri is a major cultivated seaweed in Thailand and can be a potential source of bioethanol due to its high polysaccharide content. Marine yeasts collected from the surface of seaweed are poorly known, but could be a source of fermenting yeast when using seaweeds. We collected samples of G. fisheri cultivated in shrimp pond effluent from southern Thailand and isolated yeasts from their surface. Molecular methods (ITS2 sequence) were used to identify the species and ethanol production was measured using algal powder hydrolyzed with 1 M of H2SO4 as a substrate. These species (Candida parapsilosis, Candida glabrata, Kodamaea ohmeri) were identify and used in fermentation experiment. These three yeast species produced different amounts of ethanol (per gram sugars) with C. glabrata producing the highest amount (2.5 × 10−2 g ethanol g−1 sugars) and C. parapsilosis (1.70 × 10−2 g ethanol g−1 sugars) the lowest. This study revealed that epiphytic yeasts isolated from G. fisheri have potential for use in the production of ethanol.

Study on Pore Structure of Seaweed Particles After Combustion

In this work, the particles of two seaweeds, Enteromorpha clathrata (E. clathrata) (EN) and Sargassum natans (S. natans), were combusted in a fluidized bed. It was found that while combustion of EN particles was stable, there was a substantial slagging period during the combustion of S. natans particles. Seaweed and its bottom ash samples were collected, and their pore structures were determined with both mercury intrusion method and N2 adsorption–desorption method. The structural analysis revealed that the number of porosity, pore volume, and specific surface area was all increased and the internal pore in ash samples was expanded after combustion. Fractal analysis showed that while the surface of original seaweed was smooth, it became irregular and rough after combustion. This study has suggested that the ash of seaweeds with porous structure can be valuable for comprehensive utilization.

Complete genome sequence of Agarivorans gilvus WH0801T, an agarase-producing bacterium isolated from seaweed

Agarivorans gilvus WH0801T, an agarase-producing bacterium, was isolated from the surface of seaweed. Here, we present the complete genome sequence, which consists of one circular chromosome of 4,416,600bp with a GC content of 45.9%. This genetic information will provide insight into biotechnological applications of producing agar for food and industry.

Draft Genome Sequence of Marine Flavobacterium Jejuia pallidilutea Strain 11shimoA1 and Pigmentation Mutants.

Here, we present the draft genome sequence of a novel carotenoid 2′-isopentenylsaproxanthin producer, Jejuia pallidilutea strain 11shimoA1, isolated from the surface of seaweed in Japan, and the ethyl methanesulfonate-induced pigmentation mutants. This genomic information will help to not only elucidate the 2′-isopentenylsaproxanthin biosynthetic pathway but also understand the evolution of flavobacteria.

Isolation and antimicrobial activity of a lanosol derivative from Osmundaria serrata (Rhodophyta) and a visual exploration of its biofilm covering

Abstract A biologically active compound, lanosol ethyl ether (LEE), was isolated from Osmundaria serrata and its antimicrobial activity was determined against various terrestrial bacteria and fungi, and marine bacteria isolated from the surface of the seaweed. This is the first report of the presence of a lanosol derivative in O. serrata. The mean bacteriostatic and fungistatic activity of LEE was 0.27 ± 0.07 mg ml− 1 and the mean bactericidal and fungicidal activity was 0.69 ± 0.15 mg ml− 1. These values are comparable to the estimated concentration of LEE in the whole plant of 0.20 mg ml− 1. Extracts of O. serrata containing LEE also caused deformities in some bacteria that were tested. Biofilms cause the fouling of surfaces in the marine environment. The use of paints containing highly toxic metals to control their growth are ecologically harmful. Alternatives are required. The biofilm growing on the surface of this red seaweed was studied by light and scanning electron microscopy. A diverse biofilm was seen on O. serrata with bacteria even seen close to the meristematic tips of the plant. Further work is required to determine whether the concentration of the active compound in the tips is bactericidal.

Heterotrophic bacterial flora in aquaculture area around Xuejiadao

From Oct., 1999 to Oct., 2000, the heterotrophic bacterial flora in the aquaculture area around Xuejiadao was investigated. The result shows that the populations of the heterotrophic bacteria are heavier in summer and autumn than those in winter and spring. The average populations in seawater, sediment, the surface of seaweed and the surface of fish are 1.4×104cfu mL−1, 5.4×106cfu g−1, 1.5×106cfu g−1 and 1.8×103cfu cm−2, respectively. A total of 301 strains were isolated, among them 259 were Gram-negative. All the Gram-negative bacteria belong to 13 genera and some genera of Enterobacteriaceae. The communities of bacteria are slightly different among the samples. In the body surface of fish, Genus vibrio is dominant. In the remaining samples, dominant genus is Aeromonas.

Distribution of bacterial parasites and predators in the coastal sea area.

Distribution of bacterial parasites and predators, which are enumerated as the plaque-forming units (PEU) and MPN of bacterivorous protozoa respectively, was investigated in the coastal seawater, sediments, plankton, shellfish and on the surface of seaweed. Plaque-forming organisms including bdellovibrio, myxobacteria and amoebae were found in most of the sampleas and their density was affected by both the quality and quantity of bacterial inhabitants. The number of bacterivorous protozoa, flagellates and ciliates, was enumerated by the cultural MPN method established by the authors. Flagellates occurred in most of the samples, but ciliates were observed only in a part of the surface seawater and seaweed. Their distribution was affected by the quantity of prey bacteria. According to statistical analysis, thresholds for growth response or continuance of parasites and predators were found at 102-103 per ml as total viable bacteria.