Indoor mass cultivation of marine diatoms for biodiesel production using induction plasma synthesized nanosilica

One-pot reaction for the preparation of diatom hemostatic particles with effective hemostasis and economic benefits

Effective hemostatic materials have been in demand for rapid pre-hospital hemostasis in emergency situations, which can significantly reduce accidental deaths. The development of emergency hemostatic materials with rapid hemostasis, biosafety, and economical preparation is a great challenge. In this study, Ca(OH)2-complexed diatom powder hemostatic particles (Ca(OH)2-Php) were prepared based on a one-pot reaction by directly mixing various raw materials and by rotary granulation. High-temperature calcination was able to carbonate and consume the organic matter in the hemostatic particles. The crosslinked hydrogen bonds in those particles were converted to silica-oxygen bonds, the particles became more stable, and the porous structure of diatom biosilica (DBs) was exposed. Ca(OH)2-Php has high porosity, can quickly adsorb the water in blood (water absorption: 75.85 ± 6.93%), and exhibits rapid hemostasis capacity (clotting time was shortened by 43% compared with that of the control group), good biocompatibility (hemolysis rate <7%, no cytotoxicity), and simplicity of handling (conveniently debride, no residues, no tissue inflammation). This study provides a new idea for the preparation of emergency hemostatic materials, and Ca(OH)2-Php prepared by one-pot reaction has various high-quality characteristics including rapid hemostasis, wide applicability, economical preparation, and potential for large-scale production.

Biomimetic Diatom Biosilica and Its Potential for Biomedical Applications and Prospects: A Review

Diatom biosilica is an important natural source of porous silica, with three-dimensional ordered and nanopatterned structures referred to as frustules. The unique features of diatom frustules, such as their high specific surface area, thermal stability, biocompatibility, and adaptable surface chemistry, render diatoms valuable materials for high value-added applications. These attributes make diatoms an exceptional cost-effective raw material for industrial use. The functionalization of diatom biosilica surface improves its biophysical properties and increases the potential applications. This review focuses on the potential uses of diatom biosilica including traditional approaches and recent progress in biomedical applications. Not only well-studied drug delivery systems but also promising uses on bone regeneration and wound healing are covered. Furthermore, considerable aspects and possible future directions for the use of diatom biosilica materials are proposed to develop biomedical applications and merit further exploration.

Marine diatom algae cultivation in simulated dairy wastewater and biomass valorization

Liquid byproducts and organic wastes generated from dairy processing units contribute as the largest source of industrial food wastewater. Though bacteria-mediated treatment strategies are largely implemented, a more effective and innovative management system is needed of the hour. Thus, the current study involves the cultivation of centric diatoms, Chaetoceros gracilis, and Thalassiosira weissflogii in simulated dairy wastewater (SDWW) formulated using varying amounts of milk powder with artificial seawater f/2 media (ASW). The results revealed that cell density and biomass productivity were highest in the 2.5% SDWW treatment cultures of both the strains, the maximum being in C. gracilis (7.5 × 106 cells mL - 1; 21.1 mg L-1 day-1). Conversely, the total carotenoid, chrysolaminarin, and phenol content were negatively impacted by SDWW. However, a considerable enhancement in the total lipid content was reported in the 2.5% SDWW culture of both species. Furthermore, the fatty acid profiling revealed that though the total polyunsaturated fatty acid (PUFA) content was highest in the control setups, the total mono polyunsaturated fatty acid (MUFA) content was higher in the 5% SDWW setups (30.66% in C. gracilis and 33.21% in T. weissflogii). In addition to it, in the cultures utilizing energy from external carbon sources provided by SDWW, the biodiesel produced was also enhanced owing to the heightened cetane number. Thus, the current study evidently highlights the organic carbon acquisition potential of marine diatoms with the scope of providing sustainable biorefinery.

Biomass valorization of agriculture wastewater grown freshwater diatom Nitzschia sp. for metabolites, antibacterial activity, and biofertilizer

The sustainable utilization of agricultural wastewater is a major global challenge. This study evaluated the impact of agricultural fertilizer on the biomass potential of Nitzschia sp. for metabolite production, antibacterial activity, and slow release biofertilizer. Cultivation of Nitzschia sp. in agriculture wastewater (0.5 mg ml^-1) exhibited maximum cell density (12×10⁵ cells ml^-1), protein content (10.0 mg g^-1), and lipid content (14.96%). Carbohydrate and phenol content increases in a dose-dependent manner with 8.27 mg g^-1 and 2.05 mg g^-1 at a concentration of 2 mg ml^-1 respectively. There was a 2.1-fold increment in chrysolaminarin content. Both gram-negative and gram-positive bacteria were susceptible to the antibacterial activity of the biomass. The effects of using diatom biomass as a biofertilizer were evaluated on the growth of periwinkle plants, which showed significant improvements in leaf development, branching at an early stage, flowering, and a marked increase in shoot length. Diatom biorefinery holds immense potential in addressing agriculture wastewater recycling and sustainable generation of high-value compounds.

Nutrient acclimation in benthic diatoms with adaptive laboratory evolution

The growth of marine diatom algaeChaetoceros gracilisandThalassiosira weissflogiiin agricultural fertilizers and additional carbon sources were evaluated. The main objective behind the study was to increase the growth and productivity of the diatom acclimatized under adaptive laboratory culture conditions. In optimized conditions,C.gracilisshowed the highest cell density in NPK (202.5 ± 2.6 × 10⁵ cells mL^-1), maximum carbohydrate (212.8 ± 4.0 mg g^-1) and protein (133.9 ± 1.5 mg g^-1) in urea. In contrast,T.weissflogiishowed the highest cell density in glycerol (148.2 ± 2.5x10⁵ cells mL^-1), maximum carbohydrate in glycerol (273.7 ± 3.3 mg g^-1), and protein in sucrose (126.2 ± 0.7 mg g^-1). Lipid content was maximum in glycerol (73.4 ± 0.6%) and glucose (39.7 ± 0.2%) in C. gracilisand T. weissflogii respectively. Increased pigment production and chrysolaminarin concentration were obtained in both marine species. The study highlights the importance of adaptive laboratory evolution as an promising tool in enhancing productivity in diatom algae.

Mass cultivation of marine diatoms using local salts and its impact on growth and productivity

Diatoms are of great interest for many biotechnological applications. The present study highlights the comparative analysis for mass cultivation under the effect of seawater made from table salt (TS), rock salt (RS), and synthetic seawater in the presence of normal silica and induction coupled plasma (ICP) nanosilica (Nano Si) for inducing diatom growth. Out of all the test formulations, RS-f/2 Nano Si showed the best results with maximum cell density (3.16x107±0.04 and 3.24x107±0.05 cells mL^-1), carbohydrate (403.0±3.4 and 398.0±8.1 mg g^-1), and chrysolaminarin yield (66.2±5.5 and 49.3±5.1 mg g^-1) in both Chaetoceros gracilis and Thalassiosira weissflogii respectively. The presence of a rich pigment profile and lipids further highlights the importance of TS and RS for cost-effective mass culturing. Results reveal that mass cultivation of marine diatoms with TS and RS in the presence of nanosilica not only reduces costs but also enhances metabolite production.

Diatoms as a biotechnological resource for the sustainable biofuel production: a state-of-the-art review

The greenhouse gas emission from fossil fuel and higher economic cost in its transportation are stimulating scientists to explore biomass energy production at the local level. In the present review, the authors have explored the prospects of commercial-scale biofuels production from the microalgal group, diatoms. Insights on suitability of mass cultivation systems for large-scale production of diatoms have been deliberated based on published literature. Diatoms can proliferate extracting nutrients from the wastewater and the same biomass can be harvested for biofuel production. Residues can be further utilized for the formation of other bioproducts and biofertilizers. The residual applications of diatoms from mass culture are estimated to compensate for the additional costs incurred in the removal of impurities. Well-planned research is required to optimize the commercial-scale production of biofuels from diatoms. The aim of this review is therefore, to demonstrate the economically feasible, hygienically safe cultivation of diatoms on nutrients from wastewater, limitations in using diatoms for biofuel production, and how these limitations can be shorted out for optimum utilization of diatom for biofuel production.

Growth of marine diatoms on aquaculture wastewater supplemented with nanosilica

The aquaculture industry is a significant producer of highly nutritious food for the increasing global population. However, the wastewater generated from aquaculture ponds is an emerging global issue. The present study demonstrates the culturing of marine diatoms (Chaetoceros gracilis and Thalassiosira weissflogii) in different proportions of aquaculture wastewater (AQW) coupled with inductively coupled plasma nanosilica (ICP-SiO₂) and further explores their biorefinery potential concomitant nutrient removal. Thalassiosira weissflogii showed maximum carbohydrate content (79.47 ± 0.21 mg g^-1) in 10% and protein content (27.09 ± 0.21 mg g^-1) in 30% AQW: ICP-SiO₂. Chaetoceros gracilis showed maximum carbohydrate content (91.64 ± 0.11 mg g^-1) in 50% and protein content (27.75 ± 0.05 mg g^-1) in 10% AQW: ICP-SiO₂ respectively. Additionally, Chaetoceros gracilis showed maximum nitrate uptake in 30%, phosphate in 50%, and ammonia in 50% AQW: ICP-SiO_2. While Thalassiosira weissflogii showed maximum nitrate, phosphate, and ammonia removal efficiency in 50%, 50%, and 10% AQW: ICP-SiO₂ respectively. The study draws attention towards the utilization of diatoms in AQW treatment, aquafeed potential thus imparting a global circular bioeconomy.

Key Targets for Improving Algal Biofuel Production

A number of technological challenges need to be overcome if algae are to be utilized for commercial fuel production. Current economic assessment is largely based on laboratory scale up or commercial systems geared to the production of high value products, since no industrial scale plant exits that are dedicated to algal biofuel. For macroalgae (‘seaweeds’), the most promising processes are anaerobic digestion for biomethane production and fermentation for bioethanol, the latter with levels exceeding those from sugar cane. Currently, both processes could be enhanced by increasing the rate of degradation of the complex polysaccharide cell walls to generate fermentable sugars using specifically tailored hydrolytic enzymes. For microalgal biofuel production, open raceway ponds are more cost-effective than photobioreactors, with CO2 and harvesting/dewatering costs estimated to be ~50% and up to 15% of total costs, respectively. These costs need to be reduced by an order of magnitude if algal biodiesel is to compete with petroleum. Improved economics could be achieved by using a low-cost water supply supplemented with high glucose and nutrients from food grade industrial wastewater and using more efficient flocculation methods and CO2 from power plants. Solar radiation of not <3000 h·yr−1 favours production sites 30° north or south of the equator and should use marginal land with flat topography near oceans. Possible geographical sites are discussed. In terms of biomass conversion, advances in wet technologies such as hydrothermal liquefaction, anaerobic digestion, and transesterification for algal biodiesel are presented and how these can be integrated into a biorefinery are discussed.