Phosphate is an important fertilizer added to improve the crop yield. Utilization of such phosphate is facilitated by certain microorganisms which solubilize the phosphate and enable the plants to absorb it. The ability of such microorganisms to solubilize phosphate is influenced by several factors such as soil composition, which includes heavy metals. Siddhi Patel and Shalini Rajkumar, in their article, “Genetics of Phosphate Solubilization”, describe various methods that can be used to increase the solubilization of phosphate by microorganisms and how the genetics of microorganisms can be exploited to develop recombinant microorganisms, which show enhanced ability to solubilize phosphate. The authors review various strategies that have been reported to activate the enzymes that facilitate phosphate solubilization and also mechanisms to reduce or neutralize the effect of heavy metals in the soil.

Pharmaceutical industry is looking at herbal medicines as a viable alternative, as there is an increasing support from governments, better acceptability among people and less side-effects. This has put enormous pressure on the cultivation of these herbs under natural conditions, and hence many organizations are resorting to plant tissue culture as an alternative for growing and supplying these medicinal herbs for drug development and production. Gymnema sylvestra has been reported to have antidiabetic, antiobesity, hypocholesterolemic, anti-inflammatory and antimicrobial effects and hence finds widespread use in the preparation of herbal medicines. Hence plant tissue culture plays a very important role in meeting the heavy demand for this plant, and plant biotechnologists are looking at ways to improve the yield of the active principle in this plant by altering the growth conditions. Pokharkar A A and Deokule S S, in their research paper, “In Vitro Production of Callus Biomass by Using Plant Growth Regulators and a Comparative Study of Gymnemic Acid Quantity from Gymnema sylvestre (Retz.) R. Br.” have studied the effect of plant growth regulators on gymnemic acid and also the yield of gymnemic acid in natural plants grown under different environmental conditions.

Statins are a group of compounds that show remarkable inhibition to cholesterol synthesis and help in reducing risks associated with hypercholesterolemia. Mevastatin is a member of polyketide compounds and has been found to be quite effective in controlling cholesterol synthesis. Statins are produced by various microorganisms by fermentation and the yield of statins varies depending on the fermentation conditions. M Zaffer Ahamed, Bibhu Prasad Panda, Saleem Javed and Mohd. Ali, in their paper, “A Hybrid Evolutionary Factorial Method for Optimizing Mevastatin Production Under Solid-State Fermentation”, have used evolutionary operation with factorial design methodology in the production of mevastatin by solid-state fermentation using Penicillium citrinum and have shown that P. citrinum produced three times more mevastatin than P. brevicompactum.

Peptide deformylase is being evaluated as a potential target in the development of certain drugs, particularly, in eubacteria since the enzyme deals with the initiation of protein synthesis. Formylation and deformylation of the methionine residue play an important role in the initiation of translation of several microorganisms but not of mammalian cells or eukaryotes. Hence this enzyme is being investigated as an important target in the development of new antimicrobial agents. Molecular dynamic studies are important to understand the crystal structure, conformation and structure activity relationship in such proteins. These studies help in identifying the location of potential binding sites in the molecule and help in predicting the effect of binding to such sites. The molecular dynamic simulation studies made in vacuum by Shyamal Sharma, Apurba Kanti Deb and Asim Kumar Bothra, in their paper, “Global and Local Properties of Zinc Containing Peptide Deformylase Through Molecular Dynamics Simulation in Vacuum and Aqueous Environment”, have shown that the peptide deformylase of E. coli is not a flexible molecule and its conformation is quite fixed and stable, thus making it more amenable for drug binding studies.

The next article deals with an interesting and emerging area in nanotechnology, namely, nanomaterials. Nanoparticles offer unusual but useful optical, chemical and electronic properties which are challenging areas in material sciences. Further, use of microorganisms to produce nanoparticles simultaneously reduces the toxicity due to metals like silver in the environment and presents an interesting approach. N Prabhu, N Revathi, R Darsana, M Sruthi, P Chinnaswamy and D Joseph Pushpa, Innocent, in their paper, “Antibacterial Activities of Silver Nanoparticles Synthesized by Aspergillus fumigatus”, have demonstrated detoxification/bioremediation of silver nitrate by a fungus, A. fumigatus to stable silver nanoparticles which could be incorporated into inert materials like clothing with antibacterial activity. Many metals have antibacterial activity, but the role of silver as an antibacterial agent is well-established in medicine to treat wounds. The authors have shown that nanoparticle silver produced by A. fumigatus, when incorporated into surgical dressings, exhibited antibacterial activity against S. aureus.

Symbiotic relationship between plants and microbes is well-known and this plays a very important role in plant nutrition, health and also in maintaining the soil quality. Arbuscular Mycorrhizal Fungus (AMF) is one such microbe which plays several beneficial symbiotic roles in the life cycle of plants and enrichment of soil. These microbes are thus obligate biotrophs and hence cannot be cultivated in the laboratory under defined synthetic culture conditions. Traditional pot culture and aeroponic culture are the methods used with some success. The authors have attempted to grow these fungi as co-culture with spores of Glomus microcarpum var. microcarpum and with transgenic hairy roots of Ipomoea batata in a simple bioreactor designed for this purpose. The authors, R Pratap Chandran and V P Potty, in their paper, “Arbuscular Mycorrhizal Fungal Inoculum Production Using Ipomoea batata Hairy Roots in Bioreactor”, have shown 45-fold higher production of biomass of hairy roots of Ipomoea batata, suggesting that this technology will be viable when scaled up for commercial production of AMF.

- - V Sritharan
Consulting Editor