Dr. D. Dhanasekaran Assistant Professor Department of Microbiology Bharathiadasan University

1. Actinobacteria Basics and Biotechnological Applications Dr. D. Dhanasekaran Assistant Professor Department of Microbiology Bharathiadasan University Tiruchirappalli 620 024 Tamilnadu Email: dhansdd@gmail.com

2. Actinobacteria? • Actinobacteria are prokaryotes with extremely high metabolic potentiality. • They are found in virtually every natural substrate, such as soils and compost, freshwater basins, foodstuffs and the atmosphere. Deep seas, however, do not offer a favourable habitat. • They produce numerous substances essential for health such as antibiotics, enzymes, immunomodulators, etc. • During the last few decades actinomycetes have become the most fruitful source for antibiotics.

3. Role of actinobacteria in the Marine environment Actinobacteria have a profound role in the marine environment. The degradation and turnover of various materials are a continuous process mediated by the action of a variety of microorganisms. There is a speculation that the increase or decrease of a particular enzyme-producing microorganism may indicate the concentration of natural substrate and conditions of the environment. The cellulolytic, proteolytic, amylolytic, lipolytic, chitinolytic, phosphate- solubilizing activities of marine actinobacteria were reported. Actinobacteria are also reported to contribute to the breakdown and recycling of organic compounds

4. Actinobacteria: Key resource in Microbial technology Antibiotics Enzymes Enzyme inhibitors Anticancer compounds Single cell protein Antifouling compound Amino acids Vitamins Biosurfactant Pigments Probiotics- Poultry growth development Larvicidal compounds- Mosquito control Waste degradation- Bioconversion- Xenobiotics degradation Composting Plant Growth- Frankia Biofertilizer Weed management-Allelochemicals

5. They include some of the most common soil life. • Playing an important role in decomposition of organic materials, such as cellulose and chitin and thereby playing a vital part in organic matter turnover and carbon cycle. • This replenishes the supply of nutrients in the soil and is an important part of humus formation. • Other Actinobacteria inhabit plants and animals, including a few pathogens, such as Mycobacterium, Corynebacterium, Nocardia, Rhodococcus and a few species of Streptomyces.

6. Kingdom: Bacteria • Phylum: Actinobacteria (Margulis) • Class: Actinobacteria • Subclass/Orders • Acidimicrobidae • Acidimicrobiales • Actinobacteridae • Actinomycetales • Bifidobacteriales • Coriobacteridae • Coriobacteriales • Rubrobacteridae • Rubrobacteriales • Sphaerobacteridae • Sphaerobacteriales

7. Soil Actinobacterial community • The composition of the Actinobacterial community and their distributions varies between A and B soil horizons. • The frequency of Actinobacterial population in the A horizons is around 5 to 17%. • The frequency of Actinobacterial population in the B horizons is around 4 to 15%). • The population of actinobacteria increases with depth of soil even up to horizon ‘C’ of a soil profiler. • Seasonal variation affects the population of Actinobacteria in F horizon of forest soil.

8. Characterization of Actinobacterial Isolates ACTINOBACTERIAL MORPHOLOGY • Growth of filamentous actinobacteria • Growth is from the hyphal tip

9. Methods for the taxonomic description of the Actinobacteria Classical taxonomy Classical approaches for classification make use of morphological, physiological, and biochemical characters. The classical method described in the identification key by Nonomura (1974) and Bergey’s Manual of Determinative Bacteriology (Buchanan & Gibbons, 1974) is very much useful in the identification of streptomycetes. These characteristics have been commonly employed in taxonomy of streptomycetes for many years. They are quite useful in routine identification

10. Chemotaxonomy of actinobacteria • Analysis of whole cell sugars(Lechevalier and Lechevalier, 1970) • Analysis of cell wall amino acids (Becker et al., 1965) • Fatty acid analysis (Kroppenstedt, 1985)

11. Molecular taxonomy of actinobacteria • Isolation of genomic DNA • PCR amplification of 16S rDNA • 16S rDNA sequencing • Nucleotide sequence accession • http://www.ncbi.nlm.nih.gov/genebank • Phylogenetic analysis • http://www.ncbi.nlm.nih.gov/genebank

12. Phylogentic tree derived from partial 16S rDNA gene sequence of Streptomyces sp.(DPTB16) by neighbour joining method