Macroalgal Biomass Research Articles

Effect of lead ions on biochemical behavior of Cladophora glomerata in sterilized and non-sterilized media.

Freshwater ecosystems are under peril globally due to anthropogenic influences, most notably metals. The present study aimed to evaluate the morphological and biochemical responses of Cladophora glomerata obtained from a freshwater stream to various lead concentrations (0.0, 7.5, 15, 30, and 60 mg/L Pb2+) in sterilized and non-sterilized media. Pigments, proline, malondialdehyde (MDA), total phenolic compounds (TPC), hydrogen peroxide, and protein content of the green alga were determined in response to various growing conditions. Pb2+ stress had a detrimental effect not only on biochemical components of C. glomerata but also on the algal cell's shape and surface structure. High Pb2+ concentrations significantly decreased chlorophyll-a (from 1350 μg/g in non-sterilized and 1340 μg/g in sterilized media for the control group to 1067 μg/g in non-sterilized and 1049 μg/g in sterile media at 60 mg/L Pb2+) and protein contents (from 34.47 mg/g for the sterilized and 35.89 mg/g for non-sterilized of the control to 24.82 mg/g for the sterilized and 26.18 mg/g for the non-sterilized at 60 mg/L Pb2+) of algal biomass but increased the concentrations of stress compounds (e.g., MDA, proline, and TPC). Variation in the macroalgal biomass composition was also indicated by FTIR analysis based on interactions between amino, amide, and anionic surface groups on the algal biomass and Pb2+ ions. Morphological and biochemical responses of C. glomerata reveal that non-sterile conditions encouraged the proliferation of this macroalga under Pb2+ exposure.

Biohydrogen production through energy efficient surfactant induced microwave pretreatment of macroalgae Ulva reticulata

Macroalgal biomass being rich in carbohydrates, proteins and lipids in their cell wall has been considered as the most efficient organic rich sources for biofuel (biohydrogen) production. In this study, Pluronic P-123-induced microwave pretreatment was applied to disintegrate the marine macroalgae biomass, Ulva reticulata. Microwave disintegration was done by varying the treatment time and microwave power from 0 to 40 min and 0.09 KW to 0.63 KW. A maximum chemical oxygen demand (COD) solubilization of 22.33% was achieved at a microwave power and time duration of 0.36 kW and 15 min. Chemical (Pluronic P-123, a mild surfactant) was combined with optimum microwave disintegration conditions to increase the solubilization efficiency and this combined pretreatment achieved a maximum COD solubilization of 31.02% at 10 min pretreatment time and 0.06 g per g TS of Pluronic P-123 dosage. The present study indicated that combination of surfactant with microwave pretreatment substantially improves the COD solubilization with reduced pretreatment -time than mono microwave pretreatment. An optimal hydrogen yield of 98.37 mL was achieved through this combined pretreatment. The biohydrogen data was modelled with Gompertz model and the kinetic parameters derived through this model implies that the calculated adjusted R squared values for all the samples lies between 0.95 and 0.99. This shows that the model fitted biohydrogen experimental values accurately. In addition, Pluronic P-123-induced microwave pretreatment was regarded as energy efficient and cost effective than microwave pretreatment alone with net energy production and a greater energy ratio of 504.38 kWh/Ton macroalgae and 1.2 when compared to microwave pretreatment alone (−2975.6 kWh/Ton macroalgae and 0.5).

The Detection of Green Tide Biomass by Remote Sensing Images and In Situ Measurement in the Yellow Sea of China

The world’s largest macroalgae bloom (also known as green tide) has been reported since the 29th Olympic Games in 2008, which is verified as the fast reproduction of floating green macroalgae (Ulva prolifera). It is helpful to assess the biomass of macroalgae for the government of marine environment protection. In this study, the synchronization cruise experiment was firstly introduced, which aimed to investigate the biomass evaluation of Ulva prolifera in the Yellow Sea of China. The Floating Algae Index by Polarimetric SAR image (FAIPS) was then proposed. Finally, the floating algae biomass evaluation model was demonstrated and verified, which showed an exponential relationship between FAIPS and wet biomass per area (kg/m2) of macroalgae. The model proposed in this paper can be used in the biomass assessment of floating algae in the presence of polarimetric SAR images, regardless of daylight and cloud coverage over the sea surface.

Sensory Evaluation of Rabbit Meat from Individuals Fed Functional and More Sustainable Diets Enriched with Freshwater Cladophora glomerata Macroalgal Biomass.

Maintaining meat quality is essential to sustainable livestock management. Therefore, identifying alternative feed materials while considering consumer acceptance is crucial. So, the aim of this study was to evaluate the effect of C. glomerata-biomass-supplemented feeds on rabbit muscles' physical properties, sensory profiles, and evaluators' emotional responses to them. A total of thirty 52-day-old weaned Californian breed rabbits were randomly allocated to one of three dietary treatments: standard compound diet (SCD), SCD supplemented with 4% C. glomerata (CG4), or SCD supplemented with 8% C. glomerata (CG8). After the 122-day-old rabbits were slaughtered, post-mortem dissection of the rabbit Longissimus dorsi (LD) and hind leg (HL) muscles was conducted. The physical and histomorphometric features, sensory analyses, and emotional responses to the rabbit's muscles were determined. Study results revealed CG4 and CG8 treatments significantly increased rabbit muscle moisture, while CG8 increased cooking losses in HL muscles (p < 0.05). Moreover, both CG treatments reduced the darkness and redness of fresh and cooked rabbit muscles compared to SCD (p < 0.05). CG8 treatment compared to SCD resulted in longer LD muscle fibers (p < 0.05). Evaluators discovered that the average scores for each sensory description of rabbit meat are acceptable and that consuming CG8-HL muscles can increase happiness based on emotional responses. Consequently, replacing traditional feed materials in rabbit feed with C. glomerata can lead to not only more sustainable production but also more consumer-acceptable rabbit meat.

Simplified and cost-effective modulatory photobioreactor setup for upscaling microalgal culture for research and semi-industrial purposes

Algal biomass and algal substances attract much interest from researchers, entrepreneurs, and farmers. Macroalgal biomass can be collected from the wild or cultivated in open tanks with a relatively low risk of contamination; however, achieving a sufficient amount of microalgal biomass is much more challenging, as the study of algal substances requires rather large amounts of biomass for extraction procedures and analyses. Due to budgetary constraints, most research institutes cannot afford to purchase large-scale ready-for-use photobioreactors, and knowledge regarding the self-construction and operation of such systems is not commonly shared. For this purpose, we present a straightforward, cost-effective methodology for modulatory mid-scale microalgal cultivation, using low-cost materials and instruments existing in most laboratories. We purchased a long polyethylene sleeve roll to assemble the photobioreactors and trimmed it to individual sleeves containing up to 20 L of culture medium each. A large medium volume was sterilized using commercial bleach (sodium hypochlorite), followed by dechlorination with thiosulfate. After a cultivation period of 7–14 days, flocculation induction was achieved by adding calcium hydroxide to facilitate an efficient harvest process. Cultures were enriched with CO2 in response to increasing pH throughout the cultivation process using a simple controller. Using an isolate of one of our species of interest, Mucidosphaerium pulchellum, we demonstrated how using one pH regulatory system can regulate a set of cultures (each in a different sleeve) to remain in the pH range 7.4–8.1 while saving CO2. This economical CO2-enrichment method increased algal growth rates by 23 %, reaching ca. 20 % higher total suspended solids compared to air-supplemented cultures. Such a cultivation system can be implemented with a surprisingly low budget of only USD800, efficiently producing hundreds of grams of biomass per cultivation period to support research on highly nutritious substances production and bioactive compounds discovery.

A proof of concept for inland production of the “sea-vegetable” Ulva compressa in Brandenburg (Central Europe) using regional saline groundwater

Global food security is a major challenge of this century as pointed out in the UN sustainable development goal (SDG) 2 for creating a world without hunger and malnutrition by promoting among others sustainable consumption and production pattern (SDG 12). With shrinking environmental resources there is a pressing need for alternative food sources such as edible macroalgae (“sea vegetables”). In recent years different research initiatives attempt to develop cultivation providing available freshly harvested macroalgal biomass in inland areas. In this context natural saline groundwater (brine) provides a promising solution for the cultivation of marine organisms. Here we tested firstly the suitability of regional brine from the area Brandenburg (Central Europe) for the indoor cultivation of two edible macroalgae (“sea vegetables”) the chlorophyte Ulva compressa (flat gut weed, also formerly known as Enteromorpha sp.) and the rhodophyte Ceramium virgatum (formerly known as C. rubrum). For the evaluation of brine-based media, we considered different life stages of the macroalgae (e.g., spores, germlings and reproductive thalli) determining differences in their growth rates and nutritional composition (e.g., carotenoid, chlorophyll, and fatty acid concentrations). Brine based media supported macroalgae growth and development, with differences in growth and nutritional composition depending on macroalgal species and life stage. U. compressa cultivated with brine showed a thallus development and nutritional composition comparable to that of specimen cultivated in commercial media. In contrast, results for C. virgatum were less conclusive, due to an overall low germination rate ≤ 13 % under experimental conditions. Given the high demand for fresh macroalgal biomass and limited access to costly cultivation media, we suggest that use of natural brine provides a promising approach to foster the cultivation of selected “sea-vegetables” in inland areas including urban places.

Strong correlations of sea ice cover with macroalgal cover along the Antarctic Peninsula: Ramifications for present and future benthic communities

Macroalgal forests dominate shallow hard bottom areas along the northern portion of the Western Antarctic Peninsula (WAP). Macroalgal biomass and diversity are known to be dramatically lower in the southern WAP and at similar latitudes around Antarctica, but few reports detail the distributions of macroalgae or associated macroinvertebrates in the central WAP. We used satellite imagery to identify 14 sites differing in sea ice coverage but similar in terms of turbidity along the central WAP. Fleshy macroalgal cover was strongly, negatively correlated with ice concentration, but there was no significant correlation between macroinvertebrate cover and sea ice. Overall community (all organisms) diversity correlated negatively with sea ice concentration and positively with fleshy macroalgal cover, which ranged from around zero at high ice sites to 80% at the lowest ice sites. Nonparametric, multivariate analyses resulted in clustering of macroalgal assemblages across most of the northern sites of the study area, although they differed greatly with respect to macroalgal percent cover and diversity. Analyses of the overall communities resulted in three site clusters corresponding to high, medium, and low fleshy macroalgal cover. At most northern sites, macroalgal cover was similar across depths, but macroalgal and macroinvertebrate distributions suggested increasing effects of ice scour in shallower depths towards the south. Hindcast projections based on correlations of ice and macroalgal cover data suggest that macroalgal cover at many sites could have been varying substantially over the past 40 years. Similarly, based on predicted likely sea ice decreases by 2100, projected increases in macroalgal cover at sites that currently have high ice cover and low macroalgal cover are substantial, often with only a future 15% decrease in sea ice. Such changes would have important ramifications to future benthic communities and to understanding how Antarctic macroalgae may contribute to future blue carbon sequestration.

Biosynthesis of cellulose from Ulva lactuca, manufacture of nanocellulose and its application as antimicrobial polymer

Green nanotechnology has recently been recognized as a more proper and safer tool for medical applications thanks to its natural reductions with low toxicity and avoidance of injurious chemicals. The macroalgal biomass was used for nanocellulose biosynthesis. Algae are abundant in the environment and have a high content of cellulose. In our study, we extracted parent cellulose from Ulva lactuca where consecutive treatments extracted cellulose to obtain an insoluble fraction rich in cellulose. The extracted cellulose has the same results obtained by matching it with reference cellulose, especially the same Fourier transform infrared (FTIR) and X-Ray diffraction (XRD) analysis peaks. Nanocellulose was synthesized from extracted cellulose with hydrolysis by sulfuric acid. Nanocellulose was examined by Scanning electron microscope (SEM) shown by a slab-like region as Fig. 4a and Energy dispersive X-ray (EDX) to examine the chemical composition. The size of nanocellulose in the range of 50 nm is calculated by XRD analysis. Antibacterial examination of nanocellulose was tested against Gram+ bacteria like Staphylococcus aureus (ATCC6538), Klebsiella pneumonia (ST627), and Gram-negative bacteria such as Escherichia coli (ATCC25922), and coagulase-negative Staphylococci (CoNS) to give 4.06, 4.66, 4.93 and 4.43 cm as respectively. Comparing the antibacterial effect of nanocellulose with some antibiotics and estimating minimal Inhibitory Concentration (MIC) of nanocellulose. We tested the influence of cellulose and nanocellulose on some fungi such as Aspergillus flavus, Candida albicans, and Candida tropicalis. These results demonstrate that nanocellulose could be developed as an excellent solution to these challenges, making nanocellulose extracted from natural algae a very important medical material that is compatible with sustainable development.

Concise review on seaweed photosynthesis: From physiological bases to biotechnological applications

Seaweeds play an important role for the environment, since they are photosynthetic organisms, contributing to the cycling of nutrients and to the protection and feeding of several animals. The potential for biotechnological applications of marine macroalgae biomass is enormous, and to attend the demand of the current market, the knowledge of the physiological characteristics of these organisms is essential to ensure a high productivity in cultivation systems. In this review, we contribute to the knowledge about the photosynthetic characteristics of seaweeds, describing relevant aspects of marine macroalgae and photosynthesis, and the biotechnological use of these organisms.

Macroalgae as a source of sugar and detoxifier biochar for polyhydroxyalkanoates production by Halomonas sp. YLGW01 under the unsterile condition

Macroalgae (seaweed) is considered a favorable feedstock for polyhydroxyalkanoates (PHAs) production owing to its high productivity, low land and freshwater requirement, and renewable nature. Among different microbes Halomonas sp. YLGW01 can utilize algal biomass-derived sugars (galactose and glucose) for growth and PHAs production. Biomass-derived byproducts furfural, hydroxymethylfurfural (HMF), and acetate affects Halomonas sp. YLGW01 growth and poly(3-hydroxybutyrate) (PHB) production i.e., furfural > HMF > acetate. Eucheuma spinosum biomass-derived biochar was able to remove 87.9 % of phenolic compounds from its hydrolysate without affecting sugar concentration. Halomonas sp. YLGW01 grows and accumulates a high amount of PHB at 4 % NaCl. The use of detoxified unsterilized media resulted in high biomass (6.32 ± 0.16 g cdm/L) and PHB production (3.88 ± 0.04 g/L) compared to undetoxified media (3.97 ± 0.24 g cdm/L, 2.58 ± 0.1 g/L). The finding suggests that Halomonas sp. YLGW01 has the potential to valorize macroalgal biomass into PHAs and open a new avenue for renewable bioplastic production.

Patterns and drivers of macroalgal ‘blue carbon’ transport and deposition in near-shore coastal environments

The role of macroalgae (seaweed) as a global contributor to carbon drawdown within marine sediments – termed ‘blue carbon’ – remains uncertain and controversial. While studies are needed to validate the potential for macroalgal‑carbon sequestration in marine and coastal sediments, fundamental questions regarding the fate of dislodged macroalgal biomass need to be addressed. Evidence suggests macroalgal biomass may be advected and deposited within other vegetated coastal ecosystems and down to the deep ocean; however, contributions to near-shore sediments within coastal waters remain uncertain. In this study a combination of eDNA metabarcoding and surficial sediment sampling informed by seabed mapping from different physical environments was used to test for the presence of macroalgal carbon in near-shore coastal sediments in south-eastern Australia, and the physical factors influencing patterns of macroalgal transport and deposition. DNA products for a total of 68 macroalgal taxa, representing all major macroalgal groups (Phaeophyceae, Rhodophyta, and Chlorophyta) were successfully detected at 112 near-shore locations. These findings confirm the potential for macroalgal biomass to be exported into near-shore sediments and suggest macroalgal carbon donors could be both speciose and diverse. Modelling suggested that macroalgal transport and deposition, and total organic carbon (TOC), are influenced by complex interactions between several physical environmental factors including water depth, sediment grain size, wave orbital velocity, current speed, current direction, and the extent of the infralittoral zone around depositional areas. Extrapolation of the optimised model was used to predict spatial patterns of macroalgal deposition and TOC across the coastline and to identify potentially important carbon sinks. This study builds on recent studies providing empirical evidence for macroalgal biomass deposits in near-shore sediments, and a framework for predicting the spatial distribution of potential carbon sinks and informing future surveys aimed at determining the potential for long-term macroalgal carbon sequestration in marine sediments.

Herbivorous Fish Microbiome Adaptations to Sulfated Dietary Polysaccharides.

Marine herbivorous fish that feed primarily on macroalgae, such as those from the genus Kyphosus, are essential for maintaining coral health and abundance on tropical reefs. Here, deep metagenomic sequencing and assembly of gut compartment-specific samples from three sympatric, macroalgivorous Hawaiian kyphosid species have been used to connect host gut microbial taxa with predicted protein functional capacities likely to contribute to efficient macroalgal digestion. Bacterial community compositions, algal dietary sources, and predicted enzyme functionalities were analyzed in parallel for 16 metagenomes spanning the mid- and hindgut digestive regions of wild-caught fishes. Gene colocalization patterns of expanded carbohydrate (CAZy) and sulfatase (SulfAtlas) digestive enzyme families on assembled contigs were used to identify likely polysaccharide utilization locus associations and to visualize potential cooperative networks of extracellularly exported proteins targeting complex sulfated polysaccharides. These insights into the gut microbiota of herbivorous marine fish and their functional capabilities improve our understanding of the enzymes and microorganisms involved in digesting complex macroalgal sulfated polysaccharides. IMPORTANCE This work connects specific uncultured bacterial taxa with distinct polysaccharide digestion capabilities lacking in their marine vertebrate hosts, providing fresh insights into poorly understood processes for deconstructing complex sulfated polysaccharides and potential evolutionary mechanisms for microbial acquisition of expanded macroalgal utilization gene functions. Several thousand new marine-specific candidate enzyme sequences for polysaccharide utilization have been identified. These data provide foundational resources for future investigations into suppression of coral reef macroalgal overgrowth, fish host physiology, the use of macroalgal feedstocks in terrestrial and aquaculture animal feeds, and the bioconversion of macroalgae biomass into value-added commercial fuel and chemical products.

An antibacterial and bioactive sponge incorporating Codium sp.-mediated biosynthesized silver nanoparticles for the management of high exudate wounds

The antibacterial sponges with interconnected porous structure, high biocompatibility and antibacterial activity are important for wound healing applications. In this work, Codium sp. — polysaccharide based sponges incorporating silver nanoparticles biosynthesized by macroalgal biomass were produced. The biosynthesized silver nanoparticles were successfully produced through chemical reduction mediated by residual macroalgal biomass. As the main findings, the nanoparticles presented a hydrodynamic diameter of 46.10 ± 0.22 nm and a zeta potential value of −18.20 ± 1.02 mV, which remained stable for 14 days. In turn, the porous sponges based on Codium sp. polysaccharide incorporating the silver nanoparticles were obtained by freeze-drying. The produced sponges presented a controlled swelling (≈2000 % stable during at least 35 h of incubation) and biodegradation profile (sponges lost about 80 % of its weight after 5 days). Further, the sponges demonstrated to be biocompatible in contact with fibroblast cells and able to avoid microorganism growth. Overall, the results suggested the promising properties of the sponges incorporating biosynthesized silver nanoparticles to act as antibacterial and bioactive wound dressing able to absorb the excess of wound exudate, promoting cell proliferation and impairing the occurrence of a skin infection. Such evidence reinforces the properties of macroalgal-derived products to be applied in the biomedical field and the use of macroalgal biomass for the biosynthesis of metallic nanoparticles.

Bioconversion of Sargassum wightii to ethanol via consolidated bioprocessing using Lachnoclostridium phytofermentans KSM 1203

Contemporary studies suggest that macroalgal biomass is an attractive and alternate source for ethanol production to replace fossil fuel. Sargassum wightii, a brown macroalgae, rich in cellulose is suitable for bioethanol production. This investigation focused on the pretreatment, enzyme saccharification and fermentation for bioethanol production through consolidated bioprocessing (CBP) using Lachnoclostridium phytofermentans KSM 1203 isolate. The cellulose extraction from S. wightii biomass and essential medium components for L. phytofermentans KSM 1203 were optimized using Response Surface Methodology. The alkali pretreatment on S. wightii biomass removed lignin and hemicelluloses with the cellulose recovery of 82.35%. The sodium hyphochlorite treatment removes other contaminants, results the semi crystalline to amorphous cellulose structure. The optimized medium components for L. phytofermentans KSM 1203 was found to be pre-treated biomass 3.92 g/L, peptone 2.21 g/L, dipotassium hydrogen phosphate 1.84 g/L and sodium chloride 2.03 g/L and for the growth and co-production of cellulase activity and ethanol productivity. The maximum bioethanol yield was obtained under the optimal conditions to be 13.75 ± 0.687 g/L for L. phytofermentans KSM 1203 from pre-treated S. wightii biomass. Hence, this investigation suggests that wild type L. phytofermentans KSM 1203 strain could be exploited for the utilization of cellulose for production ethanol in a single-step CBP procedure.

A circular bioprocess application of algal-based substrate for Bacillus subtilis natto production of γ-PGA.

Poly-γ-glutamic acid (γ-PGA) is a bio-derived water-soluble, edible, hydrating, non-immunogenic polymer. Bacillus subtilis natto is a wild-type γ-PGA producer originally isolated from Japanese fermented natto beans whose activity has been shown to be enhanced through ion-specific activation of Extrachromosomal DNA maintenance mechanisms. Being a GRAS γ-PGA producer, this microorganism has attracted great interest in its use within an industrial context. Here we successfully synthesised amorphous, crystalline and semi-crystalline γ-PGA between 11-27g/L. In line with circular economy principles, scalable macroalgal biomass has been evaluated as substrate for γ-PGA, displaying great potential in both yields and material composition. In this study whole cell, freeze dried seaweed -namely Laminaria digitata, Saccharina latissima and Alaria esculenta-were pre-treated by means of mechanical methods, sterilised and subsequently inoculated with B. subtilis natto. High shear mixing was found to be the most suitable pre-treatment technique. Supplemented L. digitata (9.1g/L), S. latissima (10.2g/L), A. esculenta (13g/L) displayed γ-PGA yields comparable to those of standard GS media (14.4g/L). Greatest yields of pure γ-PGA were obtained during the month of June for L. digitata (Avg. 4.76g/L) comparable to those obtained with GS media (7.0g/L). Further, pre-treated S. latissima and L. digitata complex media enabled for high molar mass (4,500kDa) γ-PGA biosynthesis at 8.6 and 8.7g/L respectively. Compared to standard GS media, algal derived γ-PGA displayed significantly higher molar masses. Further studies will be necessary to further evaluate the impact of varying ash contents upon the stereochemical properties and modify the properties of algal media based γ-PGA with the aid of key nutrients; however, the material synthesised to date can directly displace a number of fossil fuel derived chemicals in drug delivery applications, cosmetics, bioremediation, wastewater treatment, flocculation and as cryoprotectants.

Littoral enchytraeids and Eisenia fetida earthworms facilitate utilization of marine macroalgae as biofertilizers

Marine macroalgae are often used as biofertilizers in the coastal regions across the world. However, the effects of soil fauna in macroalgae decomposition are not fully understood. We conducted a microcosm experiment to assess the possibility of using a mixture of native Enchytraeidae and the model earthworm species Eisenia fetida to accelerate decomposition of dominant algae taxa from White Sea (Fucus spp.) and Black Sea (Cystoseira spp.) after their amendment to soil with simultaneous mitigation of the associated carbon dioxide (CO2) emissions. During 45 days of the microcosm experiment, we measured CO2 emission from the soil and evaluated changes in macroalgal biomass, δ13C and δ15N isotopic signatures of soil, macroalgae, earthworm faeces and enchytraeid tissues as well as bulk carbon and nitrogen content in soil. The mass of Cystoseira spp. residues, unlike that of Fucus spp., significantly decreased during the experiment (by approximately 73 % of the initial level). This effect was amplified by the co-action of E. fetida and Enchytraeidae (by 65 % of the initial). The addition of Enchytraeidae into microcosms led to the more than two-fold reduction of CO2 emission in all treatments. Differential enrichment of soil and earthworm casts with macroalgae-derived carbon and nitrogen, as suggested by stable isotope analysis, indicated that macroalgae-originating carbon pathway is rather driven by a synergistic activity of enchytraeids and earthworms (δ13C enrichment up to 4.8 ‰). Nitrogen transfer was dependent on the microbial activity and could be modulated and channelized by enchytraeids, whose δ15N values strictly corresponded to algal taxa. This highlights the importance of annelids in increasing the value of macroalgae as biofertilizers.

A First Marine Vibrio Biocatalyst to Produce Ethanol from Alginate, which is a Rich Polysaccharide in Brown Macroalgal Biomass.

The use of un-utilized feedstock and seawater for material and/or energy production using marine microbial catalysts is one potential option toward contributing to the development of a more sustainable society. Ethanol production from alginate, which is an oxidized polysaccharide present in brown seaweed, is extremely difficult due to the imbalance of reducing power in the microbial cells. Production of ethanol by such means has so far been unsuccessful using marine microbial biocatalysts. To produce ethanol from alginate, an alternative pathway consisting of a pyruvate decarboxylase gene (pdc) and an alcohol dehydrogenase II gene (adhII) derived from Zymomonas mobilis strain ZM4 was implemented into a metabolically engineered bacterium, Vibrio halioticoli, which is a representative marine alginate decomposer. No ethanol from alginate was produced in the wild-type V. halioticoli; however, the engineered V. halioticoli harboring the pdc and adhII operon (Pet operon), designated to the V. halioticoli (Pet), was able to produce 880mg/L ethanol in maximum from 1.5% alginate for 72h. The Pet operon also worked on the other marine alginolytic vibrios for ethanol production from alginate. This is the first case of ethanol production from alginate using marine bacterial biocatalysts under seawater-based media.

Biohydrogen production from macroalgae via sonic biosurfactant disintegration: An energy efficient approach

An energy-efficient disintegration approach used to produce biohydrogen from marine macroalgae biomass ( Chaetomorpha antennina ) was demonstrated in this study. The suggested research aimed to explain the function of macroalgae disintegration by sonication (DS) and disintegration by a sonic surfactant (DSS) in biohydrogen production. Biosurfactant dosage (3 μ L/g TS), sonic intensity (50%) and disintegration duration (30 min) were found to be an optimum conditions for DSS with respect to dissoluted organics release (DOR). Volatile fatty acids (VFA) generation was higher in DSS (1845 mg/L) than DS (864 mg/L) When DS and DSS were compared, DSS had a substantially higher disintegration efficiency (DE) and biohydrogen yield (26%, 147 mL H 2 /gCOD) than DS (21.5%, 121 mL H 2 /gCOD). Net energy (NE) obtained in DSS (0.044 kWh/kg of biomass) was more than the DS (−0.02 kWh/kg of biomass). DSS had a higher energy ratio of 1.8, while DS had a lower energy ratio of 0,7. Overall, DSS was found to be an energetic way to produce biohydrogen. • Sonication and biosurfactant accelerate the disintegration of macroalgae together. • This innovative technique results in the disintegration at an SSE of 9000 kJ/kg TS. • Kinetic analysis depicts that DSS had quick disintegration rate. • The combinative disintegration achieved a maximum biohydrogen production of (147 mL H 2 /g COD).

An effective biological treatment method for marine aquaculture wastewater: Combined treatment of immobilized degradation bacteria modified by chitosan-based aerogel and macroalgae (Caulerpa lentillifera)

Aquaculture has expanded significantly in recent years, and the effluent it produces has had a significant negative impact on the environment. The survival and growth rates of aquaculture products may impact by the eutrophication of the water body if the effluent from aquaculture is not handled. In this study, chitosan-based aerogel was used as a carrier to immobilize the degrading bacteria, and the adsorption capacity of the carrier material for methyl blue was 1.30 mg·g−1. The Caulerpa lentillifera was added to the shrimp tank at the same time as a biofilter, and a composite in-situ treatment system using microbes and macroalgae was built to handle the effluent from the mariculture industry to test the reduction rates of the nutrients from the wastewater. The outcomes demonstrated that the immobilized bacteria used had reduction rates of COD, NH4+ and NO2− in wastewater that were 48.82%, 9.14% and 40.74% greater than those of the free bacteria, respectively. The reduction effect of macroalgae for nutrients in wastewater is also very ideal, in which the reduction rates of TP and TN reach 32.43% and 74.94% respectively. When the immobilized degrading bacteria and macroalgae are combined, the reduction rates of COD, TN and TP in water reach 68.61%, 59.03% and 34.25%. At the same time, the survival rate of shrimp and the biomass of macroalgae have increased to a positive extent, with increases of 12.5% and 140%, respectively. These results demonstrate that the introduction of immobilized degrading bacteria and macroalgae into the shrimp culture system can effectively reduce the accumulation of nutrients in the shrimp culture system and have a positive impact in a variety of ways.

Carbon dioxide removal via macroalgae open-ocean mariculture and sinking: an Earth system modeling study

Abstract. In this study, we investigate the maximum physical and biogeochemical potential of macroalgae open-ocean mariculture and sinking (MOS) as an ocean-based carbon dioxide removal (CDR) method. Embedding a macroalgae model into an Earth system model, we simulate macroalgae mariculture in the open-ocean surface layer followed by fast sinking of the carbon-rich macroalgal biomass to the deep seafloor (depth&gt;3000 m), which assumes no remineralization of the harvested biomass during the quick sinking. We also test the combination of MOS with artificial upwelling (AU), which fertilizes the macroalgae by pumping nutrient-rich deeper water to the surface. The simulations are done under RCP 4.5, a moderate-emissions pathway. When deployed globally between years 2020 and 2100, the carbon captured and exported by MOS is 270 PgC, which is further boosted by AU of 447 PgC. Because of feedbacks in the Earth system, the oceanic carbon inventory only increases by 171.8 PgC (283.9 PgC with AU) in the idealized simulations. More than half of this carbon remains in the ocean after cessation at year 2100 until year 3000. The major side effect of MOS on pelagic ecosystems is the reduction of phytoplankton net primary production (PNPP) due to the competition for nutrients with macroalgae and due to canopy shading. MOS shrinks the mid-layer oxygen-minimum zones (OMZs) by reducing the organic matter export to, and remineralization in, subsurface and intermediate waters, while it creates new OMZs on the seafloor by oxygen consumption from remineralization of sunken biomass. MOS also impacts the global carbon cycle by reducing the atmospheric and terrestrial carbon reservoirs when enhancing the ocean carbon reservoir. MOS also enriches dissolved inorganic carbon in the deep ocean. Effects are mostly reversible after cessation of MOS, though recovery is not complete by year 3000. In a sensitivity experiment without remineralization of sunken MOS biomass, the whole of the MOS-captured carbon is permanently stored in the ocean, but the lack of remineralized nutrients causes a long-term nutrient decline in the surface layers and thus reduces PNPP. Our results suggest that MOS has, theoretically, considerable CDR potential as an ocean-based CDR method. However, our simulations also suggest that such large-scale deployment of MOS would have substantial side effects on marine ecosystems and biogeochemistry, up to a reorganization of food webs over large parts of the ocean.