Culture of agar yielding red alga Gracilaria edulis was carried out in fibreglass tanks by providing running seawater and aeration under a shed with transparent roof. The seed material was pretreated for 12 hours at different concentrations of growth promoters IAA, IBA, GA, Ascorbic acid, EDTA and Inositol. In general, more increase in growth and biomass was obtained in the plants pretreated with lower concentrations of these growth promoters.
Digital library
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The effect of repeated harvesting on the growth of Gelidiella acerosa was studied for one year from August '87 to July '88 and Gracilaria corticata var. corticata for two years from July '87 to May '89. The growth of these agar yielding seaweeds depended on the harvesting season and the interval between successive harvests. The regrowth of these red algae continues as long as the basal rhizomatous portion is intact with the substratum. Hence harvest should be done by pruning the plants leaving the basal portions instead of plucking the whole plants. The commercial exploitation of G. acerosa should be made only during April to July and G. corticata var. corticata during April to June and September to November giving ample interval for their regrowth to harvestable size.
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The study was carried out in a private nursery in Al-Qasim district located in Babil governorate in the period from 1/9/2018 to 1/9/2019 to study the effect of spraying with marine algae extract (Agazone) and cytokinin spray (CPPU) on the growth of local sour lemon grafted on the origin of Citrus aurantium. The experiment was carried out according to the design of the complete random sectors and three replicates, where the experiment included spraying four concentrations of seaweed extract (Agazone) 0, 3, 6, 9ml /L-1 and four levels of spray regulator growth (CPPU) 0,2,4,8 mg/L-1. The results showed a significant effect in all the studied traits, especially the treatment of spraying with Agazone algae extract at the concentration of 9 mL/-1 and spraying with growth regulator CPPU at the concentration of 8 mg/ L-1 as it achieved a significant increase in seedling height, number of leaves, area of leaves, increase plant stem diameter rate. The stem was 78.75 cm, 83.42 cm, 63.83 leaves. Seedlings-1, 65.33 leaves. Seedlings-1, 1401.25 creamy 2. Seedlings-1, 1633.56 creamy 2. Seedlings-1, 1.65 mm, 1.44 mm as well as leaf content of chlorophyll and nitrogen were 47.89 SPAD, 47.98 SPAD, 2.47%, 2.44% respectively for both study factors.
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Background: Recent studies using batch-fermentation suggest that the red macroalgae Asparagopsis taxiformis has the potential to reduce methane (CH4) production from beef cattle by up to ~ 99% when added to Rhodes grass hay; a common feed in the Australian beef industry. These experiments have shown significant reductions in CH4 without compromising other fermentation parameters (i.e. volatile fatty acid production) with A. taxiformis organic matter (OM) inclusion rates of up to 5%. In the study presented here, A. taxiformis was evaluated for its ability to reduce methane production from dairy cattle fed a mixed ration widely utilized in California, the largest milk producing state in the US.
Results: Fermentation in a semi-continuous in-vitro rumen system suggests that A. taxiformis can reduce methane production from enteric fermentation in dairy cattle by 95% when added at a 5% OM inclusion rate without any obvious negative impacts on volatile fatty acid production. High-throughput 16S ribosomal RNA (rRNA) gene amplicon sequencing showed that seaweed amendment effects rumen microbiome consistent with the Anna Karenina hypothesis, with increased β-diversity, over time scales of approximately 3 days. The relative abundance of methanogens in the fermentation vessels amended with A. taxiformis decreased significantly compared to control vessels, but this reduction in methanogen abundance was only significant when averaged over the course of the experiment. Alternatively, significant reductions of CH4 in the A. taxiformis amended vessels was measured in the early stages of the experiment. This suggests that A. taxiformis has an immediate effect on the metabolic functionality of rumen methanogens whereas its impact on microbiome assemblage, specifically methanogen abundance, is delayed.
Conclusions: The methane reducing effect of A. taxiformis during rumen fermentation makes this macroalgae a promising candidate as a biotic methane mitigation strategy for dairy cattle. But its effect in-vivo (i.e. in dairy cattle) remains to be investigated in animal trials. Furthermore, to obtain a holistic understanding of the biochemistry responsible for the significant reduction of methane, gene expression profiles of the rumen microbiome and the host animal are warranted.
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Experiments were conducted in Mayagüez, Puerto Rico, to assess the effects of a commercially available extract of the brown alga Ascophyllum nodosum on ‘Palmer’ and ‘Parvin’ mangos grown for transplants. The extract was soil-applied biweekly at 0 to 5 ml/L, using 150 ml of aqueous solution per plant per application. Both varieties responded similarly to the alga extract. Increasing the extract rate resulted in increased leaf chlorophyll content (up to 25% higher) and accelerated scion shoot height gain (up to 22%). These results indicate that Ascophyllum alga extracts can be used to reduce the time necessary to grow mango transplants.
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Experiments were conducted with tetrasporophytes of Gelidium pusillum (Stackhouse) Le Jolis, Pterocladia heteroplmos (Boergesen) Umamaheswara Rao & Kaliaperumal, and Gelidiopsis variabilis (Greville) Schmitz, to determine the effects of various environmental factors on the liberation of spores. The ability to liberate spores and the quantity of spores shed by these three red algae varied with the different environmental conditions tested. Submerged condition of the plants, long day condition at low illuminance, sea water of 30 to 40/00 salinity and 25 to 30°C temperature were found to be favourable for maximum sheddingofsporcs at Visakhapatnam. The variability observed in spore-shedding under short- and long-day conditions was considered to be due to the photosynthetic effect also noticed in the growth of certain red algae.
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With the exhaustion of fossil-based fuels, microalgae have attracted great interest as a renewable energy feedstock. Microalgae are photosynthetic microorganisms with rapid growth and the potential for production of lipids, proteins, and carbohydrates. However, the capital costs of algae production have been prohibitive for commercial biofuel production. Efforts to further increase algal growth rates and lipid content have attracted significant attention over the past decades to improve biofuel cost-effectiveness. Nevertheless, a fledgling algal industry has emerged in the past decades, but it has primarily focused on protein, nutraceutical, and other high value products from algae. Efforts to improve algal growth rates, however, will benefit nearly all applications of algae. One promising approach is coculturing algae with bacteria to increase algae growth rates and production of biofuel precursors, achieving a win-win outcome. In the research described in this dissertation, efforts were made to improve our understanding of how bacteria alter growth and composition of suspended algae cultures, with a particular focus on plant-growth promoting bacteria (PGPB).
PGPB, such as Azospirillum brasilense, have the potential to significantly increase algal growth rates through a variety of mechanisms including the production auxin hormones such as indoel-3-acetic acid (IAA). In Chapter 3, a set of lab-scale photobioreactor experiments are described in which the effect of live A. brasilense, exogenous IAA, and spent medium from A. brasilense are studied on two green algae. A. brasilense and IAA were found to promote growth (11-90%) at the expense of energy storage product accumulation in suspended cultures of Chlorella sorokiniana and Auxenochlorella protothecoides. Co-cultures and exogenous IAA stimulated growth in both algae types, but the effect was stronger in C. sorokiniana. These same treatments also suppressed neutral lipids (particularly triacylglycerol) and starch during exponential growth of C. sorokiniana. IAA and co-cultures suppressed starch in A. protothecoides. Spent medium from A. brasilense was also tested and found to promote growth slightly in C. sorokiniana but significant suppress growth in A. protothecoides. It also led to significantly different compositional changes compared to using live A. brasilense, indicating that bioactive constituents in A. brasilense secretions are transient or that physical cell attachment is important for ensuring adequate mass transfer of these constituents.
The finding that A. brasilense suppressed starch and neutral lipid content of algae raised questions about how A. brasilense mediates oxidative stress in algae. Many algae, including those in this study, are known to accumulate neutral lipid and starch under conditions that induce oxidative stress. Consequently, it was hypothesized that A. brasilense alleviates oxidative stress in algae, thereby promoting growth and suppressing energy storage products. Moreover, PGPB bacteria are known to alleviate the effects of stress conditions in several plants, but the stress- alleviating effects on the algae are not well understood. To evaluate the impacts of A. brasilense on oxidative stress in C. sorokiniana and the consequent changes in biomass composition, algae were co-cultured with A. brasilense under Cu and nitrogen stressors as described in Chapter 4. The results showed that both stressors induced oxidative stress and reduced chlorophyll content. Adding A. brasilense, and to a lesser extent, exogenous IAA, could partially rescue C. sorokiniana from the effects of oxidative stress. In fact, there was no significant difference in ROS levels between nitrogen-limited co-cultures and nitrogen-replete monocultures of C. sorokiniana. This indicates that A. brasilense could rescue the algae from the nitrogen limitation stress, which in turn explained why the presence of A. brasilense led to faster growth, higher chlorophyll content, and lower starch content, as we observed in this study.
The finding that the PGPB, A. brasilense, could promote green algae growth by 11-90%, depending on the algae strain, raised questions about how much more effective PGPB are compared to non-PGPB bacteria. Past research has shown that the non-PGPB, E. coli, can increase algal growth by similar margins. In Chapter 5, a side-by-side comparative study between a PGPB and non-PGPB organism is described. Efforts were made to understand the benefit of “universal” symbiosis mechanisms between algae and bacteria (e.g. cofactor exchange, dissolved O2-CO2 exchange) versus the benefits of PGPB-specific mechanisms (e.g. hormone exchange). The effect of the PGPB, Azospirillum brasilense, the non-PGPB, Escherichia coli, and a recently-isolated strain, Bacillus megaterium, were tested on three green algae: C. sorokiniana UTEX 2714, A. protothecoides UTEX 2341 and C. sorokiniana UTEX 2805. Results showed that, all three bacteria stimulated growth in C. sorokiniana UTEX 2714 and A. protothecoides UTEX 2341, but the effect was stronger in C. sorokiniana. They all led to significantly different compositional changes. Interestingly, the PGPB, A. brasilense slightly suppressed growth in C. sorokiniana UTEX 2805, although the effect was not statistically significant, whereas the other two bacteria significantly increased growth in this strain. This was surprising given that A. brasilense strongly promoted growth in C. sorokiniana UTEX 2714. Additionally, the algae biomass composition, nutrient uptake as well as algal photosynthate changes were measured. The latter indicated significant consumption and cycling of photosynthate, likely generating CO2 for algae. Moreover, the riboflavin metabolite, lumichrome was also detected in co-cultures containing A. brasilense (0.4-0.6 ng/ml) and E. coli (5.5-13 ng/ml). A dose response study showed that lumichrome at 1 to 10 ng/ml led to small but statistically significant increases in growth of C. sorokiniana UTEX 2805 and A. protothecoides.
Riboflavin metabolites and other vitamin cofactors from a wide range of bacteria likely confer growth benefits to algae. Such mechanisms are present in interactions between algae and both PGPB and non-PGPB. In sum, understanding such coculture relationship details may provide guidance for the cost-effective algae bioenergy and bioproduct development.
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Isocaloric (3.05 kcal gG ) ingredient blends were factorially formulated using three levels each of 1 DDGS (20, 25 and 30% db), protein (30, 32.5 and 35% db) and feed moisture content (25, 35 and 45% db), along with appropriate quantities of tapioca starch, soybean meal, fish meal, whey, vitamin and mineral mix to produce a balanced diet for tilapia feed. The ingredient blends were extruded using a laboratory-scale single screw extruder with varying screw speeds (100, 150 and 200 rpm) and extruder barrel temperatures (100, 125 and 150°C). The resulting extrudates were subjected to extensive analyses of physical properties, which included moisture content, unit density, bulk density, expansion ratio, sinking velocity, water absorption, water solubility, color (L*, a* and b*) and pellet durability indices. Several extruder parameters, including moisture content at the die, apparent viscosity, specific mechanical energy, mass flow rate, net torque and die pressure were measured to quantify the extruder behavior during processing. All process settings used produced viable extrudates, but some were of better quality than others. For example, increasing the DDGS levels from 20-30% db, protein content from 30-35% db, feed moisture content from 25-45% db and processing temperature from 100-150°C significantly decreased the PDI values by 7.50, 16.2, 17.2 and 16.6%, respectively. Increasing the feed moisture content from 25-45% db resulted in a substantial increase in SME values by 256.2%. On the other hand, increasing the screw speed from 100-200 rpm significantly decreased the SME values by 33.7%. This study highlights the importance of experimentally determining the effects of feed ingredients and process variables when developing aquafeeds from novel materials.
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Methane (CH4) emission from livestock contributes immensely to climate change accounting roughly 28% of global anthropogenic CH4 emission (Beauchemin et al. 2008). CH4 is one of the potent greenhouse gases (GHG) with 25 times more global warming potential than carbon dioxide (CO2) (Eckard et al. 2010; Jeyanathan et al., 2014; Bai et al., 2016). Enteric CH4 production also results in significant energy loss to the animals which amounts to 2 to 12% of the gross energy intake (Martin et al. 2010; Benchaar and Greathead, 2011; Patra, 2012). Therefore, safe and effective enteric methane mitigation strategies has positive contribution to both the environment and animal productivity.
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This study aimed to evaluate the effects of twenty species of tropical macroalgae on in vitro fermentation parameters, total gas production (TGP) and methane (CH4) production when incubated in rumen fluid from cattle fed a low quality roughage diet. Primary biochemical parameters of macroalgae were characterized and included proximate, elemental, and fatty acid (FAME) analysis. Macroalgae and the control, decorticated cottonseed meal (DCS), were incubated in vitro for 72 h, where gas production was continuously monitored. Post-fermentation parameters, including CH4 production, pH, ammonia, apparent organic matter degradability (OMd), and volatile fatty acid (VFA) concentrations were measured. All species of macroalgae had lower TGP and CH4 production than DCS. Dictyota and Asparagopsis had the strongest effects, inhibiting TGP by 53.2% and 61.8%, and CH4 production by 92.2% and 98.9% after 72 h, respectively. Both species also resulted in the lowest total VFA concentration, and the highest molar concentration of propionate among all species analysed, indicating that anaerobic fermentation was affected. Overall, there were no strong relationships between TGP or CH4 production and the .70 biochemical parameters analysed. However, zinc concentrations .0.10 g.kg21 may potentially interact with other biochemical components to influence TGP and CH4 production. The lack of relationship between the primary biochemistry of species and gas parameters suggests that significant decreases in TGP and CH4 production are associated with secondary metabolites produced by effective macroalgae. The most effective species, Asparagopsis, offers the most promising alternative for mitigation of enteric CH4 emissions.
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Marine Agronomy Group, CAFNRM, UH-Hilo
200 W. Kawili st., HI 96720, USA
Contact: Marine.Agronomy.Group@gmail.com
Funding for this web portal is provided by the World Wildlife Fund and the University of Hawaii-Hilo.