Current Biotechnology - Volume 1, Issue 2, 2012

A total of 596 fungal endophytes were isolated from ~2000 bark and twig samples of five medicinal plants from Clusiaceae family of Western Ghats, India, during three seasons viz., rainy, winter and summer. The isolated endophytes belonged to different fungal classes which were Ascomycetes (0.6%), Coelomycetes (19.3%), Hyphomycetes (52.1%), Zygomycetes (1.3%) and Sterile mycelia (0.7%). The most frequently recovered endophytes were Pestalotiopsis sp., Trichoderma sp., Myrothecium sp., Acremonium sp., Fusarium oxysporum and Aspergillus niger. A few other species recovered were Aspergillus spp., Ascochyta sp., Botrytis cinera, Botryodiplodea theobromae, Chaetomium sp., Cladosporium sp., Colletotrichum spp., Fusarium spp., Morteirella sp., Nigrospora oryzae, Penicillium sp., Paecilomyces sp., Phyllosticta sp. and Verticillium sp. Endophytes recovery was significantly more during the rainy season than winter and summer seasons.

The benefits of olive oil in nutrition were correlated with the prevention and therapy for many diseases. Many studies established an association with the low rate of heart disease deaths and the Mediterranean diet, especially the consumption of olive oil. Olive oil contains many bioactive molecules that could explain its multiple therapeutic effects. When isolated, olive oil biomolecules have shown their specific therapeutic effects towards many diseases including cardiovascular, cancer, arthrosclerosis, osteoporosis and immunity deregulation. Moreover some of these biomolecules possess antimicrobial activity. In this review, we are interested in therapeutic potentials of olive oil biomolecules in relation to variable extraction processes.

Bacteria are capable of forming inorganic crystals either intracellularly or extracellularly. Calcite (calcium carbonate) precipitation is a well-known example of extracellular bacterial biomineralization. Certain species of marine moderately halophilic bacteria have been shown to precipitate minerals in water supplemented with artificial marine salt media and differing Mg2+:Ca2+ concentration ratios. Formation of fluorescent calcite associated with specific catalysis by the thermophilic bacterium Geobacillus thermoglucocidasius and its possibility for industrial application is also documented. Although various chemical methods have been extensively developed for recovering precious metals from aqueous solutions, another possible method is recovery using intracellular microbial reduction of gold ions in solution. Microbial recovery of precious metals is potentially attractive as an environmentally friendly alternative to conventional methods. Researchers and engineers in materials science have only recently begun to focus on biomineralization. This review discusses seminal historical and recent research on bacterial biomineralization and its applications, focusing on the formation of calcite and precious metal-containing crystal species. Additionally, bacterial calcification as it relates to the panspermia theory is discussed.

Aspartase catalyzes the reversible deamination of aspartic acid to produce fumarate and ammonia and in specific conditions, produce aspartic acid from the products of deamination reaction. Since aspartase is one of the most specific enzymes, an improved process has been developed using aspartase for the production of aspartic acid in 1960. Aspartase is typically a bacterial enzyme and most of the studies on its enzymatic, structural and functional behavior have been carried out on Escherichia coli and Bacillus species. Various attributes at cellular and molecular level, including strain improvements through random mutagenesis and site-directed mutagenesis have been reported to describe the diverse kinetic aspects of the enzyme. In an attempt to provide imperative and comparative knowledge of aspartase from the existing literature, this review covers its sources, production, purification, characterization, immobilization, cloning and expression, crystal structure, applications, and future perspectives.

Galactokinase, a member of the GHMP (galactokinase, homoserine kinase, mevalonate kinase, phosphomevalonate kinase) family of kinases, catalyses the ATP-dependent phosphorylation of galactose at position 1 on the sugar. This reaction is important in the Leloir pathway of galactose catabolism. The need to produce monosaccharides phosphorylated at position 1 for the synthesis of complex molecules, including aminoglycoside antibiotics, has stimulated interest in exploiting the catalytic potential of galactokinases. However, the enzyme is quite specific, generally only catalysing the phosphorylation of D-galactose and closely related molecules. Directed evolution strategies have identified a key tyrosine residue (Tyr-371 in the Escherichia coli enzyme) which, although distant from the active site, influences the specificity of the enzyme. Alteration of this residue to histidine in E. coli and Lactococcus lactis galactokinases dramatically expanded the substrate range to include both D- and L-sugars. Similar experiments with the human enzyme demonstrated that alteration of the equivalent tyrosine (Tyr-379) to cysteine, lysine, arginine, serine or tryptophan increased the catalytic promiscuity of the enzyme. It has been hypothesised that these specificity changes arise because of alterations in the flexibility of the polypeptide chain. This hypothesis has yet to be tested experimentally. The biotechnological potential of galactokinases is clearly considerable and exploitation of closely related enzymes such as Nacetylgalactosamine kinase and arabinose kinase would expand that potential still further.

Anti-coagulation treatments are required for medical conditions that become more and more frequent with the ageing of the population in developed countries (atrial fibrillation, deep-venous thrombosis, heart prosthetic valves, etc.). These treatments generally use coumarin derivative (vitamin-K antagonist), whose activity needs to be monitored in order to keep the patient in an appropriate therapeutic range. This measurement can be done in laboratories but can also be performed by the patient himself using portable devices. This paper presents the different technological ways to selfmonitor vitamin-K antagonist treatment by measuring coagulation time. It will focus on portable devices, well suited to be used at home and on device to be manipulated by the patient, thus not requiring an extensive training nor sample treatment.

Gene silencing using antisense RNA or RNA interference (RNAi) is now a popular method used in eukaryotes. However, RNAi mechanism is absent in bacteria, and hence, single-stranded antisense RNAs, DNAs or nucleic acid analogs are used. Gene silencing in bacteria are achieved by either one of the following two approaches: expressing antisense RNAs using expression plasmids or adding synthetic antisense agents into the culture media. Recently, many advances on this method have been reported. In particular, the problem of low silencing efficiency has been solved remarkably, and as a result, this method is being used practically in biotechnology. This review mainly deals with the features and applications of gene silencing as a gene function subtracting method. Also, gene disruption is described as a competing and mutually complementary method.

The chimeric oncoprotein BCR-ABL, resulting from Philadelphia (Ph) chromosome translocation, is crucial for the pathogenesis of chronic myelogenous leukemia (CML) as well as a subset of acute lymphoblastic leukemia (ALL). Due to the loss of regulatory motifs during the fusion process, BCR-ABL has constitutive tyrosine kinase activity that is critical for oncogenesis. This provides the rationale for developing drugs that specifically inhibit BCR-ABL tyrosine kinase activity. The first tyrosine kinase inhibitor (TKI), imatinib mesylate (STI571, Gleevec®), was launched in 2001, completely changing the landscape of therapy for CML. However, imatinib-resistant cases emerged in the clinic, most caused by mutations in the BCR-ABL tyrosine kinase domain or BCR-ABL gene amplification. This urged the development of next-generation TKIs that can override imatinib-resistance. Instead of inhibiting tyrosine kinase activity, an alternative strategy, currently being tested in clinical trials, is to induce BCR-ABL degradation by heat shock protein 90 inhibitors or proteasome inhibitors. A more tentative strategy is to entrap BCR-ABL in the nucleus based on the finding that nuclear BCR-ABL is pro-apoptotic. Moreover, the unique mRNA and amino acid sequences at the junctional region of BCR-ABL provide an opportunity for specific targeting by gene therapy and immunotherapy, respectively. Therefore, a deep understanding of the biology of BCR-ABL in the context of CML and the use of state-of-the-art biotechnology have aided and will continue to aid in the development of targeted therapy for BCR-ABL-driven leukemia and minimal residue disease (MRD).