Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Algal biotechnology”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1990

Algal biotechnology.

The review gives a general outline of macro- and microalgal biotechnology. The main methods by which algae are cultivated and harvested are described. The first section deals with the environmental factors affecting mass culture and the principles governing the design and operation of mass cultivation systems. The second section gives the main current and potential uses of algae: in wastewater treatment, a source of food and feed, an energy source, and in the production of common and fine chemicals, such as polysaccharides, lipids, glycerol, pigments, and enzymes. Pharmaceutical uses of algae are described, and their potential as a source of novel biologically-active compounds is discussed. Future developments and the great potential of algae are considered.

Anti-Bacterial Agents↗
PubMed2003

A mutant of the green alga Dunaliella salina constitutively accumulates zeaxanthin under all growth conditions.

A novel mutant (zea1) of the halotolerant unicellular green alga Dunaliella salina is impaired in the zeaxanthin epoxidation reaction, thereby lacking a number of the beta-branch xanthophylls. HPLC analysis revealed that the zea1 mutant lacks neoxanthin (N), violaxanthin (V) and antheraxanthin (A) but constitutively accumulates zeaxanthin (Z). Under low-light physiological growth conditions, the zea1 (6 mg Z per g dry weight or 8 x 10(-16) mol Z/cell) had a substantially higher Z content than the wild type (0.2 mg Z per g dry weight or 0.5 x 10(-16) mol Z/cell). Lack of N, V, and A did not affect photosynthesis or growth of the zea1 strain. Biochemical analyses suggested that Z constitutively and quantitatively substitutes for N, V, and A in the zea1 strain. This mutant is discussed in terms of its commercial value and potential utilization by the algal biotechnology industry for the production of zeaxanthin, a high-value bioproduct.

Chlorophyta↗
PubMed2005

Microalgae as bioreactors.

Microalgae already serve as a major natural source of valuable macromolecules including carotenoids, long-chain polyunsaturated fatty acids and phycocolloids. As photoautotrophs, their simple growth requirements make these primitive plants potentially attractive bioreactor systems for the production of high-value heterologous proteins. The difficulty of producing stable transformants has meant that the field of transgenic microalgae is still in its infancy. Nonetheless, several species can now be routinely transformed and algal biotechnology companies have begun to explore the possibilities of synthesizing recombinant therapeutic proteins in microalgae and the engineering of metabolic pathways to produce increased levels of desirable compounds. In this review, we compare the current commercially viable bioreactor systems, outline recent progress in microalgal biotechnology and transformation, and discuss the potential of microalgae as bioreactors for the production of heterologous proteins.

Bioreactors↗
PubMed2006

Isolation and characterization of a xanthophyll aberrant mutant of the green alga Nannochloropsis oculata.

Novel mutants (xan1 and xan2) of the unicellular green alga Nannochloropsis oculata are impaired in xanthophyll biosynthesis, thereby producing aberrant levels of xanthophylls. High-performance liquid chromatography (HPLC) analysis revealed that the xan1 and xan2 mutants have double the violaxanthin (V) content, but have significantly decreased lutein content in their cells compared to the wild type. Furthermore, these mutants contain two to three times more zeaxanthin than the wild type under low light (LL) growth conditions. However, this xanthophyll aberration in N. oculata did not affect the normal growth and the major cellular chemical composition of the xan1 strain. The xanthophyll pool size of the LL-grown mutant was 1.8-fold greater than that of the wild type. Under high light (HL) growth conditions, V content was substantially decreased in both the mutant and wild types because of the epoxidation state of the xanthophylls. Under LL growth conditions, the deepoxidation states of the xanthophyll pool sizes were 0.1 and 1.2 in the wild type and the mutant, respectively. However, the deepoxidation states of the xanthophyll pool sizes were 0.78 in the wild type and 0.87 in the mutant under HL growth conditions. We observed that the level of one of the commercially important xanthophylls, zeaxanthin, was higher in the mutant than in the wild type under all culture conditions. This mutant is discussed in terms of its commercial value and potential utilization by the algal biotechnology industry for the production of zeaxanthin.

Chlorophyta↗
PubMed1991

Viruses and viruslike particles of eukaryotic algae.

Until recently there was little interest or information on viruses and viruslike particles of eukaryotic algae. However, this situation is changing. In the past decade many large double-stranded DNA-containing viruses that infect two culturable, unicellular, eukaryotic green algae have been discovered. These viruses can be produced in large quantities, assayed by plaque formation, and analyzed by standard bacteriophage techniques. The viruses are structurally similar to animal iridoviruses, their genomes are similar to but larger (greater than 300 kbp) than that of poxviruses, and their infection process resembles that of bacteriophages. Some of the viruses have DNAs with low levels of methylated bases, whereas others have DNAs with high concentrations of 5-methylcytosine and N6-methyladenine. Virus-encoded DNA methyltransferases are associated with the methylation and are accompanied by virus-encoded DNA site-specific (restriction) endonucleases. Some of these enzymes have sequence specificities identical to those of known bacterial enzymes, and others have previously unrecognized specificities. A separate rod-shaped RNA-containing algal virus has structural and nucleotide sequence affinities to higher plant viruses. Quite recently, viruses have been associated with rapid changes in marine algal populations. In the next decade we envision the discovery of new algal viruses, clarification of their role in various ecosystems, discovery of commercially useful genes in these viruses, and exploitation of algal virus genetic elements in plant and algal biotechnology.

Chlorella↗
PubMed2002

Biotechnological potential of immobilized algae for wastewater N, P and metal removal: a review.

This presentation comprises a review on the use of immobilized algae for wastewater nitrogen, phosphorus and metal removal purposes. Details of the use of immobilized algae, the techniques of immobilization and the effects of immobilization on cell function are included. Particularly relevant in their use for heavy metal removal from wastewaters; upon enriching the biomass in metal, can be recoverd, thereby providing economic advantages. The use of immobilized microalgae in these processes is very adequate and offers significant advantages in bioreactors. The future of this area of algal cell biotechnology is considered.

Bioreactors↗
PubMed2024

Exploring the interactions between algae and archaea.

Algae and archaea co-exist in diverse aquatic ecosystems and play a significant role in ecological functions and biogeochemical cycles. Compared to well-studied algal-bacterial interactions, there is a lack of information on algal-archaeal interactions and how their interactions affect their physiological fitness and nutrient cycles in either artificial cultivation systems or natural environments. The vast archaeal biodiversity, as indicated by genomic sequencing and computational approaches, has stimulated great interest in exploring uncultivated archaea to expand our knowledge of algae-archaea symbiosis. In this review, we summarize the latest studies on the diversity of algae-associated archaea and their (putative) symbiotic interactions, highlight the effects of algal-archaeal interactions on biogeochemical cycles and extend such knowledge to facilitate novel archaeal isolation and a broad range of algae-based biotechnological applications.

Algal biotechnology↗
PubMed2002

A Methylobacterium-like organism from algal crusts covering silicone rubber electric insulators in Africa.

AIMS: The primary goals of this study were to isolate, identify and characterize culturable bacteria living in a close association with microalgae within green crusts covering silicone rubber electric insulators in Tanzania. METHODS AND RESULTS: Twenty-four bacterial colonies were isolated from an Apatococcus crust. Characterization by statistical analyses of total cellular protein profiles demonstrated that they were highly similar to one another. Final identification was achieved using 16S rDNA sequencing and fatty acid methyl ester profiling. These analyses revealed the presence of microbes with high similarity to Methylobacterium radiotolerans. The selected isolate, A1, displayed strong inhibitory activity against Rhizoctonia solani and was found to be resistant to relatively high concentrations of zinc in the growth medium. CONCLUSIONS: This study revealed the presence of M. radiotolerans bacteria in a novel environment--within algal crusts formed on electrical insulators in Africa. Moreover, this bacterium was found to be a predominant culturable species within those complex algal-microbial associations. The isolate also shared some traits of biotechnological importance with other members of the Methylobacterium genus. SIGNIFICANCE AND IMPACT OF THE STUDY: The data presented provide a valuable contribution concerning the formation and function of associations between green microalgae and bacteria. This study also provides some information about the utility of bacteria from the genus Methylobacterium in biotechnological applications, such as biocontrol of rhizoctoniosis and bioremediation of heavy metal-contaminated soils.

Chlorophyta↗
PubMed2006

Green Alga (Chlamydomonas reinhardtii).

This protocol describes the Agrobacterium tumefaciens-mediated nuclear transformation of a microalgae Chlamydomonas reinhardtii, using a gene construct carrying the genes coding for beta-glucuronidase (gus), green fluorescent protein (gfp), and hygromycin phosphotransferase (hpt). The transformation frequency with this protocol as revealed by hygromycin resistance was many fold higher (about 50-fold) than that of the commonly used glass bead method of transformation. The simplicity of Agrobacterium-mediated gene transfer and the high transformation frequency as well as the precision of T-DNA integration will enable further molecular dissection of this important model organism as well as other algal systems to understand basic plant metabolic processes as well as to exploit the systems for biotechnological applications.

Agrobacterium tumefaciens↗
PubMed1999

Are elicitins cryptograms in plant-Oomycete communications?

Stimulation of plant natural defenses is an important challenge in phytoprotection prospects. In that context, elicitins, which are small proteins secreted by Phytophthora and Pythium species, have been shown to induce a hypersensitive-like reaction in tobacco plants. Moreover, these plants become resistant to their pathogens, and thus this interaction constitutes an excellent model to investigate the signaling pathways leading to plant resistance. However, most plants are not reactive to elicitins, although they possess the functional signaling pathways involved in tobacco responses to elicitin. The understanding of factors involved in this reactivity is needed to develop agronomic applications. In this review, it is proposed that elicitins could interact with regulating cell wall proteins before they reach the plasma membrane. Consequently, the plant reactivity or nonreactivity status could result from the equilibrium reached during this interaction. The possibility of overexpressing the elicitins directly from genomic DNA in Pichia pastoris allows site-directed mutagenesis experiments and structure/function studies. The recent discovery of the sterol carrier activity of elicitins brings a new insight on their molecular activity. This constitutes a crucial property, since the formation of a sterol-elicitin complex is required to trigger the biological responses of tobacco cells and plants. Only the elicitins loaded with a sterol are able to bind to their plasmalemma receptor, which is assumed to be an allosteric calcium channel. Moreover, Phytophthora and Pythium do not synthesize the sterols required for their growth and their fructification, and elicitins may act as shuttles trapping the sterols from the host plants. Sequence analysis of elicitin genes from several Phytophthora species sheds unexpected light on the phylogenetic relationships among the genus, and suggests that the expression of elicitins is under tight regulatory control. Finally, general involvement of these lipid transfer proteins in the biology of Pythiaceae, and in plant defense responses, is discussed. A possible scheme for the coevolution between Phytophthora and tobacco plants is approached.

Algal Proteins↗
PubMed2004

Botryococcus braunii: a rich source for hydrocarbons and related ether lipids.

This paper presents a review on Botryococcus braunii, a cosmopolitan green colonial microalga characterised by a considerable production of lipids, notably hydrocarbons. Strains like wild populations of this alga differ in the type of hydrocarbons they synthesise and accumulate: (1) n-alkadienes and trienes, (2) triterpenoid botryococcenes and methylated squalenes, or (3) a tetraterpenoid, lycopadiene. In addition to hydrocarbons and some classic lipids, these algae produce numerous series of characteristic ether lipids closely related to hydrocarbons. This review covers the algal biodiversity, the chemical structures and biosynthesis of hydrocarbons and ether lipids and the biotechnological studies related to hydrocarbon production.

Biotechnology↗
PubMed2004

Biosorption of cesium by native and chemically modified biomass of marine algae: introduce the new biosorbents for biotechnology applications.

Biosorption batch experiments were conducted to determine the cesium binding ability of native biomass and chemically modified biosorbents derived from marine algae, namely ferrocyanide algal sorbents type 1 and type 2 (FASs1 and FASs2). The applicability of the Langmuir and Freundlich isotherms for representation of the experimental data was investigated. The cesium sorption performances of the various types of sorbents were compared using the maximum capacities (qmax values) obtained from fitting the Langmuir isotherm to the values calculated from the sorption experiments, which FASs type 1 and type 2 showed better sorption performances for cesium. FASs1 and FASs2 derived from formaldehyde and glutaraldehyde crosslinked Padina australis exhibited lower sorption capacities than those prepared from the non-crosslinked one. Most of the cesium ions were bound to FASs1, derived from Sargassum glaucescens and P. australis, in < 2 min and equilibrium reached within the first 30 min of contact. Biosorption of cesium by FASs1 derived from P. australis and Cystoseria indica was constantly occurred at a wide range of pH, between 1 and 10, and the highest removal took place at pH 4. The presence of sodium and potassium at 0.5 and 1mM did not inhibit cesium biosorption by algae biomass. The maximum cesium uptake was acquired using the large particles of FAS2 originated from S. glaucescens (2-4 mm). Desorption of cesium from the metal-laden FASs1 (from P. australis, S. glaucescens and Dictyota indica) was completely achieved applying 0.5 and 1 M NaOH and KOH, although the cesium sorption capacity of the biosorbents (from C. indica and S. glaucescens) decreased by 46-51% after 9 sorption-desorption cycles.

Adsorption↗
PubMed2002

Botryococcus braunii: a renewable source of hydrocarbons and other chemicals.

Botryococcus braunii, a green colonial microalga, is an unusually rich renewable source of hydrocarbons and other chemicals. Hydrocarbons can constitute up to 75% of the dry mass of B. braunii. This review details the various facets of biotechnology of B. braunii, including its microbiology and physiology; production of hydrocarbons and other compounds by the alga; methods of culture; downstream recovery and processing of algal hydrocarbons; and cloning of the algal genes into other microorganisms. B. braunii converts simple inorganic compounds and sunlight to potential hydrocarbon fuels and feedstocks for the chemical industry. Microorganisms such as B. braunii can, in the long run, reduce our dependence on fossil fuels and because of this B. braunii continues to attract much attention.

Biotechnology↗
PubMed1993

Transformation of Chlamydomonas reinhardtii with silicon carbide whiskers.

Nuclear transformation of intact (walled) cells of the green alga Chlamydomonas reinhardtii was achieved by agitating the cells in the presence of plasmid DNA and silicon carbide (SiC) whiskers. The protocol was used to introduce the wild-type nitrate reductase structural gene into the nitrate reductase-deficient mutant strain nit1-305. Using SiC whiskers, 10-100 transformants per 10(7) cells were routinely produced, which is comparable to transformation rates achieved by agitating the cells with glass beads. In contrast to the glass bead protocol, cell viability was very high following treatment with SiC, with greater than 80% cell survival after agitation for 10 min. Agitation with SiC whiskers appears to be an efficient method for introducing DNA into intact C. reinhardtii cells and may prove to be applicable to other algal species for which cell wall mutants or protoplasting procedures are unavailable.

Animals↗
PubMed2006

Adrenoceptor and other pharmacoactive compounds as putative antifoulants.

The search for new antifouling methods, which are non-hazardous for the marine environment, is intense. However, even if several innovations in this field of research have been made, the search for unique molecules with characteristics such as strong biological activity, low residence time in the marine environment and which target special physiological features in marine invertebrate larvae, biofilm forming bacteria or algal spores is still required. This chapter reviews the effects of biogenic amine receptor agonists and antagonists, primarily G protein-coupled receptors, on settling barnacle cypris larvae. Biotechnological research on adrenoceptor compounds as lead molecules in new antifouling technologies is also reviewed.

Adrenergic Agents↗
PubMed1992

Production of vitamins, coenzymes and related biochemicals by biotechnological processes.

Vitamins and related biofactors belong to those few chemicals with a direct positive appeal to people. There is indeed a large need for extra vitamins, other than those derived from plant and animal food sources, due to unbalanced food habits or processing, food shortage or disease. Added vitamins are now either prepared chemically or biotechnologically via fermentation or bioconversion processes. Several vitamins and related biofactors are now only or mainly produced chemically (vitamin A, cholecalciferol (D3), tocopherol (E), vitamin K2, thiamine (B1), niacin (PP or B3), pantothenic acid (B5), pyridoxine (B6), biotin (H or B8), folic acid (B9) or via extraction processes (beta-carotene or provitamin A, provitamin D3, tocopherol, vitamin F-group). However, for several of these compounds microbiological or algal methods also exist or are rapidly emerging. Others are produced practically exclusively via fermentation (ergosterol or provitamin D2, riboflavin (B2), cyanocobalamin (B12), orotic acid (B13), vitamin F-group, ATP, nucleosides, coenzymes, etc. or via microalgal culture (beta-carotene, E, F). Both chemical and microbial processes are run industrially for vitamin B2 while vitamin C (ascorbic acid) is produced via a combination of chemical reactions and fermentation processes. A survey is given here of the current state of vitamin production, with emphasis on developments and strategies for improved biotechnological production and its significance, as compared to existing chemical processes. The screening or construction of vitamin hyperproducing microbial strains is a difficult task; pathway elucidation and metabolic (de)regulation need further study; r-DNA technology has only recently been introduced; improved fermentation processes and immobilised biocatalysts bioconversions for the synthesis of chiral vitamin compounds or intermediates or derivatives are gaining importance; the recovery and purification of these vitamin compounds from their fermentation broths remains equally complex.

Biotechnology↗