The production of fish feed additives for the aquaculture industry is a thriving sector in China. These natural substances are being used for several purposes including the enhancement of the immune systems of farmed fish, promoting growth, attaining the desired flesh and skin pigmentation, as well as improving the organolepctic properties of the farmed product. At the same time, the use of such additives has no negative impacts to the farming environment.
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The effects of plant growth regulators on callus induction rate and regeneration of K. alvarezii explants was evaluated.K. alvarezii calluses were induced in vitro with kinetin (K), 6benzylaminopurine (B), 1-naphtalene acetic acid (N) and spermine (S). After 30 days, K. alvarezii explants produced filamentous calluses and isolated crystalline filaments growing from the medullar region and from cortical cells at the cut edge. The plant growth regulators 1-naphtalene acetic acid (1 mg L−1) and 6-benzylaminopurine (1 mg L−1) and the 1-naphtalene acetic acid + kinetin + spermine (1, 1, 0.018 mg L−1 respectively) combination produced 85 to 129% more calluses, with significant differences versus the control (p < 0.05). Spermine at 0.018 mg L−1 produced calluses in the apical, intercalary and basal regions of explants. Spermine also reduced callus induction time to 7 days, which is faster than previously reported induction times with other plant growth regulators. An airlift bioreactor was designed and characterized to micropropagate K. alvarezii calluses. The bioreactor had mixing times ranging from 4.6–10.3 s at T90 and T95, which is shorter than those for the Fernbach (5.2–13.4 s) and balloon flasks (6.3–17.3 s). Mixing time standard deviations were smaller for the bioreactor (1.1–4.6) than for the Fernbach (9.3–13.6) and balloon flasks (5.5–15.8), suggesting an adequate flow regime within the bioreactor. The results are useful for improving callus induction in K. alvarezii and propagating microplantlets in an airlift bioreactor, and provide baseline data for macroalgal bioreactor culture
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We previously demonstrated the suitability of seaweed aquaculture as a nutrient management tool, using the warm temperate rhodophyte Gracilaria tikvahiae McLachlan. The present follow-up study revealed an even higher nutrient bioextraction capacity in the cold-water species Saccharina latissima at 3 sites—the mouth of the Bronx River Estuary (Bronx, NY; BRE), western Long Island Sound (Fairfield, CT; WLIS) and central Long Island Sound (Branford, CT; CLIS), during winter and spring of the 2012−2013 growing season. These sites differ in temperature (BRE > CLIS > WIS), salinity (BRE < WLIS = CLIS) and nutrients (BRE >> WLIS = CLIS). We estimated that S. latissima could remove up to 180, 67 and 38 kg N ha−1 at BRE, WLIS and CLIS respectively, in a hypothetical kelp farm system with 1.5 m spacing between longlines. In the same hypothetical kelp farm system, the estimated carbon sequestration values are 1350 (BRE), 1800 (WLIS) and 1200 (CLIS) kg C ha−1. The potential monetary values of N sequestration by the sugar kelp are up to $1600 (BRE), $760 (WLIS) and $430 (CLIS) ha−1, if incorporated in the State of Connecticut Nitrogen Credit Trading Program and a carbon-pricing scheme. The potential economic values of C sequestration are up to $30−300 (BRE), $40−400 WLIS), and $24−240 (CLIS) ha−1. These results suggest that seaweed aquaculture is a useful technique for nutrient bioextraction in urbanized coastal waters, such as LIS and BRE. Alternation of the warm- and cold-water species would maximize nutrient bioextraction and augment other ecosystem services, producing economic benefits for the region while helping to manage non-source eutrophication.
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Aquatic organisms, such as microalgae (Chlorella, Arthrospira (Spirulina), Tetrasselmis, Dunalliela etc.) and duckweed (Lemna spp., Wolffia spp. etc.) are a potential source for the production of protein-rich biomass and for numerous other high-value compounds (fatty acids, pigments, vitamins etc.). Their cultivation using agro-industrial wastes and wastewater (WaW) is of particular interest in the context of a circular economy, not only for recycling valuable nutrients but also for reducing the requirements for fresh water for the production of biomass. Recovery and recycling of nutrients is an unavoidable long-term approach for securing future food and feed production. Agro-industrial WaW are rich in nutrients and have been widely considered as a potential nutrient source for the cultivation of microalgae/duckweed. However, they commonly contain various hazardous contaminants, which could potentially taint the produced biomass, raising various concerns about the safety of their consumption. Herein, an overview of the most important contaminants, including heavy metals and metalloids, pathogens (bacteria, viruses, parasites etc.), and xenobiotics (hormones, antibiotics, parasiticides etc.) is given. It is concluded that pretreatment and processing of WaW is a requisite step for the removal of several contaminants. Among the various technologies, anaerobic digestion (AD) is widely used in practice and offers a technologically mature approach for WaW treatment. During AD, various organic and biological contaminants are significantly removed. Further removal of contaminants could be achieved by post-treatment and processing of digestates (solid/liquid separation, dilution etc.) to further decrease the concentration of contaminants. Moreover, during cultivation an additional removal may occur through various mechanisms, such as precipitation, degradation, and biotransformation. Since many jurisdictions regulate the presence of various contaminants in feed or food setting strict safety monitoring processes, it would be of particular interest to initiate a multi-disciplinary discussion whether agro-industrial WaW ought to be used to cultivate microalgae/duckweed for feed or food production and identify most feasible options for doing this safely. Based on the current body of knowledge it is estimated that AD and post-treatment of WaW can lower significantly the risks associated with heavy metals and pathogens, but it is yet unclear to what extent this is the case for certain persistent xenobiotics
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A major limiting factor in the development of algae as a feedstock for the bioenergy industry is the consistent production and supply of biomass. This study is the first to access the suitability of the freshwater macroalgal genus Oedogonium to supply biomass for bioenergy applications. Specifically, we quantified the effect of CO2 supplementation on the rate of biomass production, carbon capture, and feedstock quality of Oedogonium when cultured in large-scale outdoor tanks. Oedogonium cultures maintained at a pH of 7.5 through the addition of CO2 resulted in biomass productivities of 8.33 (0.51) g DW m2 day1 , which was 2.5 times higher than controls which had an average productivity of 3.37 (0.75) g DW m2 day1 . Under these productivities, Oedogonium had a carbon content of 41–45% and a higher heating value of 18.5 MJ kg1 , making it an ideal biomass energy feedstock. The rate of carbon fixation was 1380 g C m2 yr1 and 1073.1 g C m2 yr1 for cultures maintained at a pH of 7.5 and 8.5, and 481 g C m2 yr1 for cultures not supplemented with CO2. This study highlights the potential of integrating the large-scale culture of freshwater macroalgae with existing carbon waste streams, for example coal-fired power stations, both as a tool for carbon sequestration and as an enhanced and sustainable source of bioenergy.
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Microalgal biomass and its fine chemical production from microalgae have pioneered algal bioprocess technology with few limitations such as lab-to-industry. However, laboratory-scale transitions and industrial applications are hindered by a plethora of limitations comprising expensive in culturing methods. Therefore, to emphasize the profitable benefits, the algal culturing techniques appropriately employed for large-scale microalgal biomass yield necessitates intricate assessment to emphasize the profitable benefits. The present review holistically compiles the culturing strategies for improving microalgal biomass production based on appropriate factors like designing better bioreactor designs. On the other hand, synthetic biology approaches for abridging the effective industrial transition success explored recently. Prospects in synthetic biology for enhanced microalgal biomass production based on cultivation strategies and various mechanistic modes approach to enrich cost-effective and viable output are discussed. The State-of-the-art culturing techniques encompassing enhancement of photosynthetic activity, designing bioreactor design, and potential augmenting protocols for biomass yield employing indoor cultivation in both (Open and or/closed) methods are enumerated. Further, limitations hindering the microalgal bioproducts development are critically evaluated for improving culturing techniques for microalgal cell factories, subsequently escalating the cost-benefit ratio in bioproducts synthesis from microalgae. The comprehensive analysis could provide a rational and deeper detailed insight for microalgal entrepreneurs through alternative culturing technology viz., synthetic biology and genome engineering in an Industrial perspective arena.
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There has been a good deal of interest in the potential of marine vegetation as a sink for anthropogenic C emissions (“Blue Carbon”). Marine primary producers contribute at least 50% of the world’s carbon fixation and may account for as much as 71% of all carbon storage. In this paper, we analyse the current rate of harvesting of both commercially grown and wild-grown macroalgae, as well as their capacity for photosynthetically driven CO2 assimilation and growth. We suggest that CO2 acquisition by marine macroalgae can represent a considerable sink for anthropogenic CO2 emissions and that harvesting and appropriate use of macroalgal primary production could play a significant role in C sequestration and amelioration of greenhouse gas emissions.
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Managing organic waste streams is a major challenge for the agricultural industry. Anaerobic digestion (AD) of organicwastes is a preferred option in the waste management hierarchy, as this processcangenerate renewableenergy, reduce emissions from wastestorage, andproduce fertiliser material.However, Nitrate Vulnerable Zone legislation and seasonal restrictions can limit the use of digestate on agricultural land. In this paper we demonstrate the potential of cultivating microalgae on digestate as a feedstock, either directlyafter dilution, or indirectlyfromeffluent remaining after biofertiliser extraction. Resultant microalgal biomass can then be used to produce livestock feed, biofuel or for higher value bio-products. The approach could mitigate for possible regional excesses, and substitute conventional high-impactproducts with bio-resources, enhancing sustainability withinacircular economy. Recycling nutrients from digestate with algal technology is at an early stage. We present and discuss challenges and opportunities associated with developing this new technology.
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Asparagopsis taxiformis (Asparagopsis) inhibits the production of enteric methane in ruminants. A next critical step in the implementation of this technology is the delivery of a naturally-derived product that maximises the concentration and longer-term retention of bromoform. This study (1) quantified the effects of solvent (water or oil), initial processing (intact or homogenised), and temperature (4 or 25 °C) on the stabilisation of bromoform over time, and (2) assessed the effects of increasing the biomass loading (g biomass mL−1 solvent) of Asparagopsis on the concentration of bromoform in a formulation. The most effective method was to homogenise freshly-collected Asparagopsis in oil, which resulted in the highest concentration of bromoform (19.2 ± 2.1 mg g−1 dw algae) in the homogeneous product in the shortest time (one day). In addition, the final product had a shelf life of at least 12 weeks, even when stored at room temperature (25 °C). Notably, there was an increase in the concentration of bromoform per mL of oil between each increment of biomass loading tested, with the highest concentration of bromoform of 4.04 ± 0.51 mg mL−1 in the maximum ratio of biomass to oil of 120 g 100 mL−1. The method described here provides a viable processing alternative to freeze-drying, resulting in the stabilisation of the bromoform from Asparagopsis, which will be critical to the success of using Asparagopsis on a larger scale to mitigate the production of methane in ruminants.
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Nutrient-depleted cells of T. gracilis were grown in sea water containing different concentrations of nitrate and phosphate. Growth rate of cells was ftrst studied by determining the growth constant (k) and generation time (tg)
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