title: Distribution of live and dead cells in pellets of an actinomycete Amycolatopsis balhimycina and its correlation with balhimycin productivity.
abstract: Secondary metabolites such as antibiotics are typically produced by actinomycetes as a response to growth limiting stress conditions. Several studies have shown that secondary metabolite production is correlated with changes observed in actinomycete pellet morphology. Therefore, we investigated the correlation between the production of balhimycin and the spatio-temporal distribution of live and dead cells in pellets of Amycolatopsis balhimycina in submerged cultures. To this end, we used laser scanning confocal microscopy to analyze pellets from balhimycin producing and nonproducing media containing 0.2 and 1.0 g l(-1) of potassium di-hydrogen phosphate, respectively. We observed a substantially higher fraction of live cells in pellets from cultures yielding larger amounts of balhimycin. Moreover, in media that resulted in no balhimycin production, the pellets exhibit an initial death phase which commences from the centre of the pellet and extends in the radial direction. A second growth phase was observed in these pellets, where live mycelia are seen to appear in the dead core of the pellets. This secondary growth was absent in pellets from media producing higher amounts of balhimycin. These results suggest that distribution of live and dead cells and its correlation with antibiotic production in the non-sporulating A. balhimycina differs markedly than that observed in Streptomycetes.
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
authors.forename: Kamaleshwar P
authors.initials: KP
authors.lastname: Singh
authors.forename: Amit L
authors.initials: AL
authors.lastname: Mahendra
authors.forename: Vibha
authors.initials: V
authors.lastname: Jayaraj
authors.forename: Pramod P
authors.initials: PP
authors.lastname: Wangikar
authors.forename: Sameer
authors.initials: S
authors.lastname: Jadhav
mesh_terms: D000192:Actinomycetales / Q000166:cytology* / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D018533:Biomass; D019149:Bioreactors; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D050296:Microbial Viability; D010710:Phosphates / Q000494:pharmacology; D017680:Potassium Compounds / Q000494:pharmacology; D013997:Time Factors; D014640:Vancomycin / Q000031:analogs & derivatives* / Q000096:biosynthesis
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D010710:Phosphates; D017680:Potassium Compounds; C087127:balhimycin; D014640:Vancomycin; C013216:potassium phosphate