Minimum Nutrient Requirements Research Articles

PSI-6 Growth performance of weaned pigs fed an activated zinc oxide to replace pharmacological content of dietary zinc oxide

Abstract The objective of this study was to determine the effect of replacing feed-grade zinc oxide (ZnO) with decreased contents of an activated zinc oxide (aZnO) on growth performance of weaned pigs. A total of 720 pigs (Landrace × Yorkshire × Duroc; TOPICS, Richfield, MN) with an initial body weight (BW) of 5.88 ± 0.97 kg were distributed into 60 pens with 12 pigs per pen following a randomized complete block design. After weaning at 18 d of age, pigs were fed one of five diets differing in ZnO source and Zn content during a 3-phase feeding program for 42 d (Table 1). Experimental diets were formulated to meet minimum nutrient requirements. Mortality was monitored daily and analyzed using survival analysis. Performance data were analyzed by multiple linear regression, with BW gain as dependent variable and Zn source (ZnO, aZnO) and Zn content as the independent variables for each phase. Linear regression analysis used diet A as baseline (150 ppm ZnO). In addition, groups receiving diet E and B, both supplemented with the same ZnO level during phase-1, were compared using a t-test. A linear relationship was observed between BW gain and dietary Zn content (P < 0.001) and Zn source (P = 0.026). A slope ratio between the two Zn sources indicated that pigs provided with aZnO had a 72% greater growth rate compared with ZnO. In addition, during Phase 1, when both diets B and E offered similar Zn concentrations (1,200 ppm) as ZnO and aZnO, pigs fed aZnO outperformed ZnO-fed pigs by 490 g (P < 0.001). The mortality was 7.6% less (P = 0.009) for diet C than diet A. No differences were detected among pigs fed the test diets in Phases 1, 2 and 3 for other variables. In conclusion, results show the potential of aZnO as a suitable replacement for ZnO, but also underscore the effect of dietary Zn content on pig performance and mortality. The aZnO source is a suitable replacement for ZnO, enhancing growth performance in weaned pigs and demonstrating potential for reducing overall Zn usage, thereby mitigating the environmental impact of swine production.

Phenotypic and genomic characterization of Methanothermobacter wolfeii strain BSEL, a CO2-capturing archaeon with minimal nutrient requirements.

A new variant of Methanothermobacter wolfeii was isolated from an anaerobic digester using enrichment cultivation in anaerobic conditions. The new isolate was taxonomically identified via 16S rRNA gene sequencing and tagged as M. wolfeii BSEL. The whole genome of the new variant was sequenced and de novo assembled. Genomic variations between the BSEL strain and the type strain were discovered, suggesting evolutionary adaptations of the BSEL strain that conferred advantages while growing under a low concentration of nutrients. M. wolfeii BSEL displayed the highest specific growth rate ever reported for the wolfeii species (0.27 ± 0.03 h-1) using carbon dioxide (CO2) as unique carbon source and hydrogen (H2) as electron donor. M. wolfeii BSEL grew at this rate in an environment with ammonium (NH4+) as sole nitrogen source. The minerals content required to cultivate the BSEL strain was relatively low and resembled the ionic background of tap water without mineral supplements. Optimum growth rate for the new isolate was observed at 64°C and pH 8.3. In this work, it was shown that wastewater from a wastewater treatment facility can be used as a low-cost alternative medium to cultivate M. wolfeii BSEL. Continuous gas fermentation fed with a synthetic biogas mimic along with H2 in a bubble column bioreactor using M. wolfeii BSEL as biocatalyst resulted in a CO2 conversion efficiency of 97% and a final methane (CH4) titer of 98.5%v, demonstrating the ability of the new strain for upgrading biogas to renewable natural gas.IMPORTANCEAs a methanogenic archaeon, Methanothermobacter wolfeii uses CO2 as electron acceptor, producing CH4 as final product. The metabolism of M. wolfeii can be harnessed to capture CO2 from industrial emissions, besides producing a drop-in renewable biofuel to substitute fossil natural gas. If used as biocatalyst in new-generation CO2 sequestration processes, M. wolfeii has the potential to accelerate the decarbonization of the energy generation sector, which is the biggest contributor of CO2 emissions worldwide. Nonetheless, the development of CO2 sequestration archaeal-based biotechnology is still limited by an uncertainty in the requirements to cultivate methanogenic archaea and the unknown longevity of archaeal cultures. In this study, we report the adaptation, isolation, and phenotypic characterization of a novel variant of M. wolfeii, which is capable of maximum growth with minimal nutrients input. Our findings demonstrate the potential of this variant for the production of renewable natural gas, paving the way for the development of more efficient and sustainable CO2 sequestration processes.

Determination of minimal nutrient requirements for Tenebrio molitor growth and body composition

Determination of minimal nutrient requirements for Tenebrio molitor growth and body composition

Clostridioides difficile minimal nutrient requirements for flagellar motility.

As many gastro-intestinal pathogens, the majority of Clostridioides difficile strains express flagella together with a complete chemotaxis system. The resulting swimming motility is likely contributing to the colonization success of this important pathogen. In contrast to the well investigated general energy metabolism of C. difficile, little is known about the metabolic requirements for maintaining the ion motive force across the membrane, which in turn powers the flagellar motor. We studied here systematically the effect of various amino acids and carbohydrates on the swimming velocity of C. difficile using video microscopy in conjunction with a software based quantification of the swimming speed. Removal of individual amino acids from the medium identified proline and cysteine as the most important amino acids that power swimming motility. Glycine, which is as proline one of the few amino acids that are reduced in Stickland reactions, was not critical for swimming motility. This suggests that the ion motive force that powers the flagellar motor, is critically depending on proline reduction. A maximal and stable swimming motility was achieved with only four compounds, including the amino acids proline, cysteine and isoleucine together with a single, but interchangeable carbohydrate source such as glucose, succinate, mannose, ribose, pyruvate, trehalose, or ethanolamine. We expect that the identified "minimal motility medium" will be useful in future investigations on the flagellar motility and chemotactic behavior in C. difficile, particularly for the unambiguous identification of chemoattractants.

Perceived Effects of COVID-19 Pandemic on Food Security in Southeast Nigeria

The present study evaluated the perceived effects of the COVID-19 Pandemic on food security in Southeast Nigeria. A multi-stage random technique was used to select 209 households. Data for the study were collected with the aid of a structured questionnaire and were analyzed using descriptive statistics, z-test, food security model, and Tobit regression model. Results showed that the mean household size was 9.6 persons, which indicates a large household size. The percentage rate of food consumption of the households before the Pandemic was higher relative to the COVID-19 event. Again, exorbitant prices of food materials were noticed during the COVID-19 as compared to the period before the Pandemic. About 10.5% of the households met the minimum food requirements as proposed by World Health Organization (WHO), and Food and Agriculture Organization (FAO) as against the majority of 76.1%. The three dimensions of food security which include availability, accessibility, and utilization were interposed by a number of factors, such as artificial scarcity, and an increase in food prices. Furthermore, social distancing and lockdown imposition were COVID-19 determinants of the food security status of households in the Southeast Nigeria. About 24% of the households were food-secured compared to 76% that were insecured during the Pandemic. Robust and effective food and agricultural policy formulations and implementations were recommended in Southeast Nigeria.

Algal bioplastics: current market trends and technical aspects

Plastics are undebatably a hot topic of discussion across international forums due to their huge ecological footprint. The onset of COVID-19 pandemic has exacerbated the issue in an irreversible manner. Bioplastics produced from renewable sources are a result of lookout for sustainable alternatives. Replacing a ton of synthetic plastics with biobased ones reduces 1.8 tons CO2 emissions. Here, we begin with highlighting the problem statement—Plastic accumulation and its associated negative impacts. Microalgae outperforms plants and microbes, when used to produce bioplastic due to superior growth rate, non-competitive nature to food, and simultaneous wastewater remediation. They have minimal nutrient requirements and less dependency on climatic conditions for cultivation. These are the reasons for current boom in the algal bioplastic market. However, it is still not at par in price with the petroleum-based plastics. A brief market research has been done to better evaluate the current global status and future scope of algal bioplastics. The objective of this review is to propose possible solutions to resolve the challenges in scale up of bioplastic industry. Various bioplastic production technologies have been comprehensively discussed along with their optimization strategies. Overall studies discussed show that in order to make it cost competitive adopting a multi-dimensional approach like algal biorefinery is the best way out. A holistic comparison of any bio-based alternative with its conventional counterpart is imperative to assess its impact upon commercialization. Therefore, the review concludes with the life cycle assessment of bioplastics and measures to improve their inclusivity in a circular economy.Graphical

Phycocyanin Extraction and Production of Crude Bio-Oil from Residual Biomass

Large-scale cultivation of algae is getting increasingly popular to produce environmentally sustainable crude bio-oil and other products. These phototrophs can be cultivated on non-agriculture lands with minimal nutrient requirements. If one gets multiple products from single production unit (biorefinery approach), the overall value increases leading to techno-economically favorable production. Hydrothermal Liquefaction (HTL) converts biomass into biofuels without drying the feedstock, uses water as the reaction medium at high temperature and high pressure. Nitrogen is one of the major rate-limiting factors in hydrothermal liquefaction (HTL) process. Crude bio-oil (CBO) from HTL is not suited for direct fuel applications due to undesired hetero-atoms like nitrogen and oxygen. It needs to be upgraded further, which adds on to the cost of overall processing of biofuel. Here we demonstrated that the reduction of nitrogen by removing pigment protein (phycocyanin) could significantly increase overall HTL efficiency. The CBO and extracted phycocyanin have been fully characterized and reported here.

Minimal nutrient requirements for induction of germination of Aspergillus niger conidia

Aspergillus niger reproduces asexually by forming conidia. Here, the minimal nutrient requirements were studied that activate germination of A. niger conidia. To this end, germination was monitored in time using an oCelloScope imager. Data was used as input in an asymmetric model to describe the process of swelling and germ tube formation. The maximum number of spores (Pmax) that were activated to swell and to form germ tubes was 32.54% and 20.51%, respectively, in minimal medium with 50 mM glucose. In contrast, Pmax of swelling and germ tube formation was <1% in water or 50 mM glucose. Combining 50 mM glucose with either NaNO3, KH2PO4, or MgSO4 increased Pmax of swelling and germination up to 15.25% and 5.4%, respectively, while combining glucose with two of these inorganic components further increased these Pmax values up to 25.85% and 10.99%. Next, 10 mM amino acid was combined with a phosphate buffer and MgSO4. High (e.g. proline), intermediate and low (e.g. cysteine) inducing amino acids were distinguished. Together, a combination of an inducing carbon source with either inorganic phosphate, inorganic nitrogen or magnesium sulphate is the minimum requirement for A. niger conidia to germinate.

Determinants of Small-Scale Irrigation Use and Its Effect on Household Food Security in Debay Tilatgin Woreda, East Gojjam zone, Ethiopia

In Ethiopia, agriculture is the primary determinant of economic growth and reducing level of food insecurity. But in the country in general and study area in particular, agriculture is dominated by small-scale rain-fed production. As a result, the current yield level by rural smallholder farmers in the study area has not been able to fulfill the minimum food requirements. To this end, this research aims to identify determinants of SSI use and its effect on household food security status in Dibay Tilatgin, Amhara regional state, Ethiopia. Multistage sampling technique and Kothari formula was employed to identify the final sample respondents; accordingly the final sample size was 168 (38.7% irrigation users and 61.3% non-users). Both quantitative and qualitative data from primary and secondary sources were collected through interview schedule. Descriptive, inferential statistics and binary logistic model were used to analyze the collected data. The finding of the study revealed that sex, education, household labor size, cultivable land size, frequency of extension contact, training and credit use had significant positive influence whereas farm distance from water source  had significant negative influence on SSI use. Out of the total sample households, 72 (42.9%) were food secure and 96 (57.1%) were food insecure. The study result also reported, SSI had significant and positive influence on HFSS at 1% level. Therefore, it is important to address factors affecting SSI use includes sex, education level, household labor size, cultivable land size, farm distance from water sources, training and also priority should be given to SSI development in planning and executing of policies and programs by all stakeholders. Keywords : household, food security, binary, logit DOI: 10.7176/ISDE/11-5-01 Publication date: September 30 th 2020

Nutritional Requirements for Sustaining Health and Performance During Exposure to Extreme Environments.

Dietary guidelines are formulated to meet minimum nutrient requirements, which prevent deficiencies and maintain health, growth, development, and function. These guidelines can be inadequate and contribute to disrupted homeostasis, lean body mass loss, and deteriorated performance in individuals who are working long, arduous hours with limited access to food in environmentally challenging locations. Environmental extremes can elicit physiological adjustments that alone alter nutrition requirements by upregulating energy expenditure, altering substrate metabolism, and accelerating body water and muscle protein loss. The mechanisms by which the environment, including high-altitude, heat, and cold exposure, alters nutrition requirements have been studied extensively. This contemporary review discusses physiological adjustments to environmental extremes, particularly when those adjustments alter dietary requirements.

Impact of Cultivation Condition and Media Content onChlorella vulgaris Composition.

Microalgae are a source material in food, pharmacy, and cosmetics industries for producing various products including high-protein nutritional supplements, synthetic pharmaceuticals, and natural colors. A promising algal source for such productions is Chlorella vulgaris which contains a considerable protein content. Similar to other microalgae, its desirability is minimal nutrient requirements since they are unicellular, photosynthetic, and fast-growing microorganisms. Another propitious option to be produced by C. vulgaris is biodiesel, since it is rich in oil too. Besides, algal well thriving in presence of increased amount of carbon dioxide makes them a practicable alternative biofuel resource without some problems of the traditional ones. At the same time, C. vulgaris is also a promising source for nutraceuticals such as amino acids, vitamins, and antioxidants. This review aims to discuss the conditions need to be observed for achieving a favorable growth efficiency of the C. vulgaris, as well as targeted productions such as biomass, antioxidant, and biofuel. Additionally, different approaches to induce any specific production are also considered comprehensively.

Kinetics of Nutrient Removal in an Integrated Suspended Growth Reactor

Wastewater effluent discharge in a large amount of ammonia, nitrate and phosphorus lead to eutrophication the river. Eutrophication is a serious environmental issue that threaten the fishes and aquatic plants. To prevent this from happening, ammonia produced in STP and raw wastewater removal is achieved during nitrification by having an extended aeration while nitrate removal is achieved during denitrification in anoxic tank. In this research study, a pilot plant of integrated suspended growth system (i-SGS) reactor was used to achieve simultaneous removal of ammonia and nitrate. The reactor has three main compartments which are anoxic chamber, aeration camber, and clarifier and operated at a constant flow rate of 720 L/d and fixed SRT of 40 days. The RAS time was set to once every 10 minutes for 5 minutes while the IR time is once every 16 minutes for 5 minutes. The wastewater quality parameters, namely chemical oxygen demand (COD), ammonia, and nitrate were measured to determine and evaluate the removal efficiency of them in i-SGS whereas phosphorus was measured to ensure the effluent standard meet the C:N:P ratio requirement. Samples from four sampling points were taken to conduct the laboratory experiment and three replication of the results for each parameter were measured. It was determined that i-SGS was able to eliminate average 72% of COD at 46 mg/L of clarifier effluent, and achieved 95% of ammonia removal at average 1.22 mg/L of the clarifier effluent concentration while obtained 43% of nitrate removal in the anoxic tank. Last but not least, the C:N:P ratio obtained was 100:14:8, denoted that i-SGS has ample of nutrients loading provided because it is more than the minimum nutrient requirements, 100:5:1. The removal was possible through the nitrification-denitrification process in the i-SGS pilot plant bioreactor. The operational SRT of 40 days have shown to be effective and stable for the COD but not for nitrifiers. The effluent discharge of COD, ammonia and nitrate in the pilot plant i-SGS has meet the standard requirement of DOE Malaysia, standard A and B respectively.

Microalgae as source of polyhydroxyalkanoates (PHAs) - A review.

Polyhydroxyalkanoates (PHA) are biopolymers synthesized by different microorganisms and considered substitute powers for petroleum-based plastics because they have similar mechanical properties as synthetic polymers, can be processed in a similar way and are fully biodegradable. Currently commercial PHAs are produced in fermenters using bacteria and large amounts of organic carbon sources and salts in the culture media, accounting for approximately 50% of the total production costs. A greater commercial application of the PHA is limited to a decrease in the cost of production. Several studies suggest that microalgae are a type of microorganisms that can be used to obtain PHAs at a lower cost because they have minimum nutrient requirements for growth and are photoautotrophic in nature, i.e. they use light and CO2 as their main sources of energy. Thus, this work aims to provide a review on the production of PHAs of different microalgae, focusing on the properties and composition of biopolymers, verifying the potential of using these bioplastics instead of petroleum based plastics. Studies of stimulation PHA synthesis by microalgae are still considered incipient. Still, it is clear that microalgae have the potential to produce biopolymers with lower cost and can play a vital role in the environment.

USING DRIED LEFTOVER FOODS AS UNTRADITIONAL FEED IN MUSCOVY DUCK DIETS

The current work was conducted to investigate the effect of dietary leftover food inclusion on growth performance, carcass traits and some blood biochemical parameters of Muscovy ducks. Thirty six (36) two-week old ducks (average weight 393.2 g) were obtained from local commercial source and randomly distributed into 4 groups (9ducks/each). In the first group, ducklings were fed ad-libitum on grower-finisher control diet (diet 1), while birds in the second, third and fourth groups fed on diets containing 10%, 20% and 30% leftover food, respectively (diets 2, 3, 4). The experimental diets were formulated in a mash form (yellow corn, soybean meal, wheat bran and sunflower oil) to meet the minimum nutrient requirements cited by NRC (1994) for ducks. Ducklings were fed according to one phase feeding program (grower- finisher, 14- 70 days). Growth performance, carcass traits and some blood biochemical parameters were assessed. The results showed that, ducks fed on diets containing 10, 20, 30% leftover food achieved significantly (p < 0.05) higher body weight gain (3084.2±30.3, 3141.5±30.8, 3169.0±29.1 g), respectively compared with the control (2945.2±22.3g) with lower feed intake. Highest weight gain averages with best feed conversion (3.22, 3.14, and 3.11) respectively compared with the control. The highest dressing percentage was recorded in ducks fed on diet containing 30% leftover food (79.3%), while the lowest was observed in control group (75.6%). Addition of leftover food to duck diets had no significant effect (p < 0.05) on the weights of internal organ. Total serum protein, albumin and globulin values were decreased significantly (p < 0.05) by increasing the level of dietary leftover food. Inclusion of leftover food to duck diets increase significantly (p < 0.05) triglycerides and had no significant effect on serum cholesterol. Results of the current study concluded that, the best growth performance and economical feed efficiency was observed in ducks fed on diet containing 30% leftover food which surpassing all treated groups and achieved the best body weight gain.

Methods for enhancing cyanobacterial stress tolerance to enable improved production of biofuels and industrially relevant chemicals.

Cyanobacteria are photosynthetic prokaryotes that can fix atmospheric CO2 and can be engineered to produce industrially important compounds such as alcohols, free fatty acids, alkanes used in next-generation biofuels, and commodity chemicals such as ethylene or farnesene. They can be easily genetically manipulated, have minimal nutrient requirements, and are quite tolerant to abiotic stress making them an appealing alternative to other biofuel-producing microbes which require additional carbon sources and plants which compete with food crops for arable land. Many of the compounds produced in cyanobacteria are toxic as titers increase which can slow growth, reduce production, and decrease overall biomass. Additionally, many factors associated with outdoor culturing of cyanobacteria such as UV exposure and fluctuations in temperature can also limit the production potential of cyanobacteria. For cyanobacteria to be utilized successfully as biofactories, tolerance to these stressors must be increased and ameliorating stress responses must be enhanced. Genetic manipulation, directed evolution, and supplementation of culture media with antioxidants are all viable strategies for designing more robust cyanobacterial strains that have the potential to meet industrial production goals.

Agro climatic conditions, cropping pattern and its profitability in South Andaman District of Bay Islands

South Andaman district is a group of 10 inhabited islands spread over an area of 310.6 thousand ha as a part of Andaman and Nicobar group of islands in Bay of Bengal. Shifting cultivation on slopes, land degradation, high intensity rainfall, poor crop harvest, low cropping intensity, non availability of labour, high price of agricultural produce imported from mainland and limited employment opportunities resulted into acute poverty in this region. The study revealed that major cultivated crops(vegetable: 1317 ha, paddy: 216.1 ha, maize: 55 ha, ginger: 51.5 ha, sweet potato: 46 ha, tapioca: 26.5 ha, turmeric: 19.5 ha, green gram: 7.2 ha, black gram: 6.5 ha)were not at all economic due to lower net returns and lower benefit-cost ratios (BCR). It was found that the higher net returns were obtained from ginger cultivation (Rs 4, 23, 900) followed by tapioca (Rs 3, 68, 160), sweet potato (Rs 2, 42, 760), vegetables (Rs 2, 07, 760), turmeric (Rs 1, 15, 450), mustard (Rs 19, 125), maize (Rs 11, 430) and arhar (Rs 10, 375). Benefit cost ratio (BCR) was found to be highest in case of tapioca (3.06) followed by sweet potato (2.68), vegetables (2.17), ginger (2.00), arhar (1.53), mustard (1.46), green gram (1.38), turmeric (1.30) and black gram (1.23). In order to avail maximum returns, crops having higher net returns and BCRs need to be allocated more area. Therefore, limited area should be put under paddy, maize, green gram and black gram to meet the minimum food requirement of the district and surplus area to be used for growing crops like ginger, tapioca, sweet potato, vegetable having higher BCRs and net returns to make the agriculture profitable and sustainable.

Probing the Genome-Scale Metabolic Landscape of Bordetella pertussis, the Causative Agent of Whooping Cough.

ABSTRACTWhooping cough is a highly contagious respiratory disease caused by Bordetella pertussis. Despite widespread vaccination, its incidence has been rising alarmingly, and yet, the physiology of B. pertussis remains poorly understood. We combined genome-scale metabolic reconstruction, a novel optimization algorithm, and experimental data to probe the full metabolic potential of this pathogen, using B. pertussis strain Tohama I as a reference. Experimental validation showed that B. pertussis secretes a significant proportion of nitrogen as arginine and purine nucleosides, which may contribute to modulation of the host response. We also found that B. pertussis can be unexpectedly versatile, being able to metabolize many compounds while displaying minimal nutrient requirements. It can grow without cysteine, using inorganic sulfur sources, such as thiosulfate, and it can grow on organic acids, such as citrate or lactate, as sole carbon sources, providing in vivo demonstration that its tricarboxylic acid (TCA) cycle is functional. Although the metabolic reconstruction of eight additional strains indicates that the structural genes underlying this metabolic flexibility are widespread, experimental validation suggests a role of strain-specific regulatory mechanisms in shaping metabolic capabilities. Among five alternative strains tested, three strains were shown to grow on substrate combinations requiring a functional TCA cycle, but only one strain could use thiosulfate. Finally, the metabolic model was used to rationally design growth media with >2-fold improvements in pertussis toxin production. This study thus provides novel insights into B. pertussis physiology and highlights the potential, but also the limitations, of models based solely on metabolic gene content.IMPORTANCE The metabolic capabilities of Bordetella pertussis, the causative agent of whooping cough, were investigated from a systems-level perspective. We constructed a comprehensive genome-scale metabolic model for B. pertussis and challenged its predictions experimentally. This systems approach shed light on new potential host-microbe interactions and allowed us to rationally design novel growth media with >2-fold improvements in pertussis toxin production. Most importantly, we also uncovered the potential for metabolic flexibility of B. pertussis (significantly larger range of substrates than previously alleged; novel active pathways allowing growth in minimal, nearly mineral nutrient combinations where only the carbon source must be organic), although our results also highlight the importance of strain-specific regulatory determinants in shaping metabolic capabilities. Deciphering the underlying regulatory mechanisms appears to be crucial for a comprehensive understanding of B. pertussis's lifestyle and the epidemiology of whooping cough. The contribution of metabolic models in this context will require the extension of the genome-scale metabolic model to integrate this regulatory dimension.

Effects of Land Fragmentation on Productivity in Northwestern Ethiopia

Generally, land fragmentation is a universal trait of all agricultural systems which affects farmland productivity and no one had documented a rural society where there was no land fragmentation. Hence, this study sought to ascertain the effects of land fragmentation on farmland productivity in the highland districts of Northwestern Ethiopia by using cross-sectional data collected from 240 respondents during 2015/16 production seasons and analyzed by using linear and Cobb-Douglass production functions. In land productivity model, 38% of variations in farmland productivity are explained by variations in independent variables including land fragmentation parameters. Average farmland size of 1.25 ha was obtained as minimum size that can generate minimum food and cash requirement of an average family of five adult equivalents. Hence, the government should come up with land use policy and population growth controlling program, which enables determining minimum economic farmland size, improving land productivity, and finding ways to strengthen off-farm activities and livestock sector to absorb more labor and enhance means of generating more income so as to decrease minimum farmland size required.

Determining the optimal nitrogen source for large-scale cultivation of filamentous cyanobacteria

As the world’s population continues to increase and the adverse effects of anthropomorphic CO2 intensify, it is becoming increasingly important to develop biofuels and chemicals from sustainable resources. Filamentous cyanobacteria, including Anabaena sp. PCC 7120, have emerged as a promising source of renewable chemicals and biofuels due to their minimal nutrient requirements and the relative ease with which they can be genetically engineered to produce a diversity of products. This study evaluated the effects of several nitrogen sources on the growth of Anabaena sp. PCC 7120, and then performed an environmental comparative study on a theoretical large-scale production process to down-select to the best nitrogen source. Sodium nitrate and ammonium chloride yielded 65 % more growth compared to the other nitrogen sources evaluated. Ammonium chloride yielded marginal savings of US$22,318 annually, compared to sodium nitrate over a 27-year lifespan of a proposed chemical production facility utilizing filamentous cyanobacteria. Sodium nitrate had substantially greater negative impacts in every environmental category compared to ammonium chloride. For example, sodium nitrate had a ∼threefold greater negative impact in human health, ecosystem quality, and resources categories. Thus, we concluded that ammonium chloride is the preferred nitrogen source in large-scale processes involving filamentous cyanobacteria.

Biodesalination: an emerging technology for targeted removal of Na+and Cl−from seawater by cyanobacteria

Although desalination by membrane processes is a possible solution to the problem of freshwater supply, related cost and energy demands prohibit its use on a global scale. Hence, there is an emerging necessity for alternative, energy and cost-efficient methods for water desalination. Cyanobacteria are oxygen-producing, photosynthetic bacteria that actively grow in vast blooms both in fresh and seawater bodies. Moreover, cyanobacteria can grow with minimal nutrient requirements and under natural sunlight. Taking these observations together, a consortium of five British Universities was formed to test the principle of using cyanobacteria as ion exchangers, for the specific removal of Na+ and Cl− from seawater. This project consisted of the isolation and characterisation of candidate strains, with central focus on their potential to be osmotically and ionically adaptable. The selection panel resulted in the identification of two Euryhaline strains, one of freshwater (Synechocystis sp. Strain PCC 6803) and one of marine origin (Synechococcus sp. Strain PCC 7002) (Robert Gordon University, Aberdeen). Other work packages were as follows. Genetic manipulations potentially allowed for the expression of a light-driven, Cl−-selective pump in both strains, therefore, enhancing the bioaccumulation of specific ions within the cell (University of Glasgow). Characterisation of surface properties under different salinities (University of Sheffield), ensured that cell–liquid separation efficiency would be maximised post-treatment, as well as monitoring the secretion of mucopolysaccharides in the medium during cell growth. Work at Newcastle University is focused on the social acceptance of this scenario, together with an assessment of the potential risks through the generation and application of a Hazard Analysis and Critical Control Points plan. Finally, researchers in Imperial College (London) designed the process, from biomass production to water treatment and generation of a model photobioreactor. This multimodal approach has produced promising first results, and further optimisation is expected to result in mass scaling of this process.