Session Speaker

Bacteria Exhibiting Antimicrobial Activities; Screening for Antibiotics and the Associated Genetic Studies
Muaz Mutaz Al-Ajlani and Shahida Hasnain
Pakistan

In the search for new antibiotics, the genus Bacillus is an excellent place to look. Bacillus species produce a large number of antibiotics representing at least 25 different basic chemical structures. Different Bacillus species have been isolated and identified i.e. Bacillus subtilis, B. amyloliquefaciens, B. cereus, B. firmus, B. licheniformis, B. mycoides and Paenibacillus polymyxa. Identified strains showed interesting biological activities e.g. inhibiting the growth of clinical isolates (Klebsilla species), strong antifungal and antialgal activities and high toxicity against Artemia sp., while their TLC and HPLC profile showed an impressive chemical diversity. All the strains were able to produce number of peptides (surfactins, iturins, fengycins, subtilin and subtilosin) in different combinations. Over 50 compounds were isolated and identified. Standard identification data and records in term of measured values for NMR and MS are presented in this work. The approach of total secondary metabolites isolation led to the isolation of new natural bioactive secondary metabolites with various biological activities: heptyl- 1 -hydroxyquinolin (NEW), indol-2-oxoacetamide (NEW), oxopentyl-acetamide (NEW) and a number of cyclic de-peptides cyclo (His, pro), cyclo (His, Leu) (NEW) and cyclo (Tyr-Pro) (NEW). Other worth of noting findings and observations included the isolation of bacillamide and macrolactins (previously known to be exclusive products from marine bacteria) from terrestrial Bacillus species, isolation of seitomycin, macrolactins and quinoline derivative (known as typical products from streptomyces) from Bacillus species and finally, the isolation of heptyl- 1 -hydroxyquinolin (NEW) as a new class of antibiotics. Presence of sboX gene was not correlated with subtilosin production, however, subtilosin and sboX were confirmed in Bacillus amyloliquefaciens for the first time. As a conclusion, this study has not only provided new bioactive compounds but also a comprehensive standard profile of Bacil lus secondary metabolites for convenient dereplication. It was also possible to add new metabolites to these records. These bioactive new products are luxuriant materials for further research work to validate proposed medical or biotechnological applications and their physiological and ecological roles.