High-value Bioactive Compounds Research Articles

Integrated algal engineering for bioenergy generation, effluent remediation, and production of high-value bioactive compounds

Increased demand for energy worldwide has resulted in increasing interest in alternative renewable sources of biofuels. Demand for improved systems of bioenergy generation, environmental remediation, and coproduction of high value bioactive compounds has led to the potential use of algae in biomass utilization. In Malaysia, palm oil industries generate high amount of solid wastes. Palm Oil Mill Effluent (POME) is estimated to be three times of the amount of crude palm oil produced. POME is a heavily polluting wastewater due to its high chemical oxygen demand (COD), high biochemical oxygen demand (BOD), and high contents of minerals such as nitrogen and phosphorus that can cause severe pollution to the environment and water resources. A combination of wastewater treatment and renewable bioenergy co-generation with recovery of high-value biochemicals would benefit the palm oil industry.

Expression and membrane-targeting of an active plant cytochrome P450 in the chloroplast of the green alga Chlamydomonas reinhardtii

The unicellular green alga Chlamydomonas reinhardtii has potential as a cell factory for the production of recombinant proteins and other compounds, but mainstream adoption has been hindered by a scarcity of genetic tools and a need to identify products that can be generated in a cost-effective manner. A promising strategy is to use algal chloroplasts as a site for synthesis of high value bioactive compounds such as diterpenoids since these are derived from metabolic building blocks that occur naturally within the organelle. However, synthesis of these complex plant metabolites requires the introduction of membrane-associated enzymes including cytochrome P450 enzymes (P450s). Here, we show that a gene (CYP79A1) encoding a model P450 can be introduced into the C. reinhardtii chloroplast genome using a simple transformation system. The gene is stably expressed and the P450 is efficiently targeted into chloroplast membranes by means of its endogenous N-terminal anchor domain, where it is active and accounts for 0.4% of total cell protein. These results provide proof of concept for the introduction of diterpenoid synthesis pathways into the chloroplast of C. reinhardtii.

Exploiting nature's chemists: high value bioactive compounds from algae

Exploiting nature's chemists: high value bioactive compounds from algae

Redirecting Photosynthetic Electron Flow into Light-Driven Synthesis of Alternative Products Including High-Value Bioactive Natural Compounds

Photosynthesis in plants, green algae, and cyanobacteria converts solar energy into chemical energy in the form of ATP and NADPH, both of which are used in primary metabolism. However, often more reducing power is generated by the photosystems than what is needed for primary metabolism. In this review, we discuss the development in the research field, focusing on how the photosystems can be used as synthetic biology building blocks to channel excess reducing power into light-driven production of alternative products. Plants synthesize a large number of high-value bioactive natural compounds. Some of the key enzymes catalyzing their biosynthesis are the cytochrome P450s situated in the endoplasmic reticulum. However, bioactive compounds are often synthesized in low quantities in the plants and are difficult to produce by chemical synthesis due to their often complex structures. Through a synthetic biology approach, enzymes with a requirement for reducing equivalents as cofactors, such as the cytochrome P450s, can be coupled directly to the photosynthetic energy output to obtain environmentally friendly production of complex chemical compounds. By relocating cytochrome P450s to the chloroplasts, reducing power can be diverted toward the reactions catalyzed by the cytochrome P450s. This provides a sustainable production method for high-value compounds that potentially can solve the problem of NADPH regeneration, which currently limits the biotechnological uses of cytochrome P450s. We describe the approaches that have been taken to couple enzymes to photosynthesis in vivo and to photosystem I in vitro and the challenges associated with this approach to develop new green production platforms.

Production of Bioenergy and Bioproducts from Food Processing Wastes: A Review

Wastes from different food processing sectors are reviewed in terms of their availability, quality, and current utilizations. Technologies for value-added processing of different food wastes into bioenergy and biochemical products are briefly discussed. Part of food wastes is currently processed as animal feeds and organic fertilizers. Large amounts of solid food wastes are buried in landfills, while liquid food wastes are released into public sewer systems. High transport and landfill costs and strict governmental regulations have led to alternative utilization of food processing wastes. The selection of an appropriate process to recover materials and energy from food wastes largely depends on the characteristics of the waste, the desired forms of bioenergy and bioproducts, and the economical feasibility. Food processing wastes from fruits, vegetables, and grains contain large amounts of primary metabolites of lipids, proteins, and carbohydrates and a broad range of high-value bioactive compounds of phenolics, terpenoids, and alkaloids. Extraction techniques have been widely investigated to obtain valuable natural compounds from plant-based processing wastes. Wet plant-based food processing wastes, which are rich in sugars, vitamins, and minerals, have been used to produce fuel alcohols, organic acids, biodegradable polymers, enzymes, antioxidants, and vitamins in biological processes. Wet food processing wastes such as slaughterhouse wastes, fruit and vegetable processing wastes, and food processing wastewater are suitable for the production of biogas and hydrogen through anaerobic digestion. Non-edible oil cakes, which are rich in protein, have been used to adjust the carbon to nitrogen ratio of feedstocks in anaerobic digestion. Dry food processing wastes, such as rice husk, sugarcane bagasse, and oilseed cakes, can be used to supply heat and power in food processing facilities through combustion and produce gaseous fuels through gasification and liquid bio-oil through pyrolysis. Meat processing wastes have high contents of protein and fat. Animal fats and grease are potential feedstocks for biodiesel production.

Positive genetic interactors of HMG2 identify a new set of genetic perturbations for improving sesquiterpene production in Saccharomyces cerevisiae

BackgroundTerpenoids and isoprenoids are an important class of natural products, which includes currently used drugs, high value bioactive and industrial compounds, and fuel candidates. Due to their industrial application, there is increasing interest in the development of S. cerevisiae strains capable of producing high levels of terpenoids.ResultsAiming to identify new gene targets which can be manipulated to increase sesquiterpene production, a set of HMG2 positive genetic interactors were assessed as single and digenic heterozygous deletions in the presence or absence of stable HMG2(K6R) overexpression. Upon single allele deletion, most genes examined led to increased sesquiterpene production in yeast cells. Tandem heterozygous deletion of a set of three genes, the ubiquitin ligases ubc7 and ssm4/doa10, and the ER resident protein pho86, led to an 11-fold increase in caryophyllene yields (125 mg/L in shake flasks) compared to cells lacking these modifications. The effect of the heterozygous deletions appears to be due to Hmg1p and Hmg2p stabilization.ConclusionHeterozygous deletions cause significant reductions in protein levels but do not lead to growth impediments frequently seen in haploid strains. By exploiting desirable haploinsufficiencies in yeast, we identified a new set of genes that can be disrupted in tandem and cause significant stabilization of Hmgp and a substantial increase in sesquiterpene production. The approach presented here allows new genetic perturbations to be compiled on yeast cell factory strains without negatively impacting cell growth and viability.

High performance separation of sparingly aqua-/lipo-soluble bioactive compounds with an ionic liquid-based biphasic system

Separation of high value bioactive compounds is a viable route to make full use of the biomass resources and improve the profitability. However, the sparing aqua- and lipo-solubility of the bioactive compounds makes their separation really challenging. Considering that ionic liquids show good solubility of biomass and could easily form biphasic systems with organic solvents, an ionic liquid (IL)-based biphasic system consisting of ionic liquid, water and ethyl acetate is proposed in this study. Ginkgolide homologues were selected as model compounds to evaluate its practicality. Adequate distribution coefficients, relatively high extraction capacity and selectivity were obtained with the novel biphasic system. The improved distribution coefficients of the ginkgolides are mainly attributed to the multiple interactions between ginkgolide and IL, which were confirmed by means of quantum chemistry calculations. Moreover, the effect of the interactions between ginkgolides and the extraction solvent on the selectivity coefficient was studied by measuring the Kamlet–Taft parameters of the extraction solvent. Based on the results of fractional extraction, which was simulated by calculation and validated by experiments, as well as the comparison of organic solvent consumption, the employed IL-based extraction would be a valid and clean method as an alternative to chromatographic methods for separating bioactive compounds in large-scale operations. It is noteworthy that the amount of organic solvents consumed with this method was supposed to be less than 1/11 of the most widely used chromatographic method.

Growth and Physiological Features of Cyanobacterium Anabaena sp. Strain PCC 7120 in a Glucose-Mixotrophic Culture

Mixotrophic growth is one potential mode for mass culture of microalgae and cyanobacteria particularly suitable for the production of high value bioactive compounds and fine chemicals. The typical heterocystous cyanobacterium Anabaena sp. PCC 7120 was grown in the presence of exogenous glucose in light. Glucose improved the cell growth evidently, the maximal specific growth rate under mixotrophic condition (0.38 d( 1) being 1.6-fold of that of photoautotrophic growth. Mixotrophy caused a variation in cellular pigment composition, increasing the content of chlorophyll a and decreasing the contents of carotenoid and phycobiliprotein relative to chlorophyll a. Fluorescence emission from photosystem II (PSII) relative to photosystem I was enhanced in mixotrophic cells, implying an increased energy distribution in PSII. Glucokinase (EC 2.7.1.2) activity was further induced in the presence of glucose. The mixotrophic culture was scaled up in a 15 L airlift photobioreactor equipped with an inner and an outer light source. A modified Monod model incorporating the specific growth rate and the average light intensity in the reactor was developed to describe cell growth appropriately. The understanding of mixotrophic growth and relevant physiological features of Anabaena sp. PCC 7120 would be meaningful for cultivation and exploitation of this important cyanobacterial strain.

Rational pathway engineering of type I fatty acid synthase allows the biosynthesis of triacetic acid lactone from D-glucose in vivo.

Metabolic pathway engineering is a powerful tool to synthesize structurally diverse and complex chemicals via genetic manipulation of multistep catalytic systems involved in cell metabolism. Here, we report the rational design of a fatty acid biosynthetic pathway, Brevibacterium ammoniagenes fatty acid synthase B (FAS-B), that allows the microbial synthesis of triacetic acid lactone (TAL) from an inexpensive feedstock, d-glucose. TAL can be chemically converted to phloroglucinol, which is a core structure for the synthesis of various high value bioactive compounds and energetic compounds such as 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). Synthesis of phloroglucinol from d-glucose using this combined biological and chemical synthesis may offer significant advantages over the current phloroglucinol manufacture, including environmental friendliness and reduction in the cost of phloroglucinol. More importantly, it represents a novel strategy for the benzene-free synthesis of aromatic chemicals.

Healthy beverage recipe contest

Crabs are one of the most diverse groups of crustaceans. Both fresh and marine crabs are an excellent source of many nutrients that are important for human health. Because of their unique flavour and delicious taste, crab meat and novel crab-based processed products are quite popular; hence the demand is increasing consistently in the domestic and global market. Further, crab processing generates a large quantity of liquid and solid waste creating disposal and land fill problems. To overcome the environmental impacts thereof, it is necessary to recycle and reuse these underutilized yet economically potential discards or by-products.Even though having immense potential in terms of nutrients and offering unique flavour profile, the importance of crab often goes unnoticed. But crabs get less special mention and are mostly considered along with other crustaceans, wherein shrimps and lobsters are debated at length. Further, crab processing generates a large quantity of by-products and solid wastes, predominantly rich in chitin. Therefore, there is a great interest for valorisation of crab processing by-products that possess biologically active products with wide applications. In light of the above, this review highlights the nutritional aspects, flavour profile, quality and health benefits of crab meat including the acceptability of crab-based value-added products. The diversified applications of valuable products derived from crab processing bio-wastes are also discussed.Crab meat is rich in protein, essential amino acids, long chain omega-3 fatty acids, and also an excellent source of vitamins and minerals. The uniqueness in taste and pleasant flavour properties of crab meat is due to volatile, non-volatile aroma and taste components, hence highly accepted by the consumers. Different innovative preservation technologies are suggested to improve the quality, safety and shelf-life of crab meat and crab-based value-added products. Further, crab processing wastes possess several high-value bioactive compounds. Green extraction is recommended for valorisation of these bioactive compounds (derivatives of chitin, protein hydrolysates and enzymes, lipids, carotenoids etc.) that have enormous applications in agriculture, environment, food, textile, pharmaceutical and other biomedical fields.

Microphase separated polymer surfaces for separation of B and T lymphocytes

There are strong demands for innovation in methodology for separation of B cells and T cells, two major subpopulations of lymphocytes, because of their essential role as key-factors for therapy and diagnosis of immuno-diseases as well as for production of high-value bioactive compounds. Cellular adsorption chromatography is one of the promising methods for separation of these lymphocyte subpopulations. This paper reviews the present status of adsorption chromatography applied to the cell separation and describes our approach to design of novel adsorbents which are able to adsorb B cells selectively among other subpopulations without any undesirable perturbation or activation of cells to be separated. A possible mechanism involved in separation of B and T cells by adsorption chromatography is also discussed in detail.