Applications of image analysis in the characterization of Streptomyces olindensis in submerged culture

Abstract

The morphology of Streptomyces olindensis (producer of retamycin, an antitumor antibiotic) grown in submerged culture was assessed by image analysis. The morphology was differentiated into four classes: pellets, clumps (or entangled filaments), branched and unbranched free filaments. Four morphological parameters were initially considered (area, convex area, perimeter, and convex perimeter) but only two parameters (perimeter and convex perimeter) were chosen to automatically classify the cells into the four morphological classes, using histogram analysis. Each morphological class was evaluated during growth carried out in liquid media in fermenter or shaker. It was found that pellets and clumps dominated in early growth stages in fermenter (due to the inoculum coming from a shaker cultivation) and that during cultivation, the breakage of pellets and clumps caused an increase in the percentage of free filaments. The criteria of morphological classification by image analysis proposed were useful to quantify the percentage of each morphological class during fermentations and may help to establish correlations between antibiotic production and microorganism morphology.

New Method for Monitoring Programmed Cell Death and Differentiation in Submerged Streptomyces Cultures

“…Streptomyces differentiation in submerged cultures has been largely ignored (16,20,22,23), since the optimization of industrial fermentations is an essentially empirical process. A keen understanding of antibiotic production and differentiation that relies on an autophagic process (PCD) is crucial to manipulating fermentation parameters and inducing the formation of the antibiotic-producing mycelium (MII).…”

Characterization and Optimization of Biosynthesis of Bioactive Secondary Metabolites Produced by Streptomyces sp. 8812

“…1(A)-(F). The clumps are irregular in shape, unlike pellets, and smaller (Denser Pamboukian et al, 2002). In 24-hour seed cultures, single live cells were observed at the periphery of the clumps (Fig.…”

Rheological and morphological characterization of Streptomyces olindensis growing in batch and fed-batch fermentations

“…Morphology was evaluated by image analysis, using a criterion for classification of the microorganism in four morphological classes (pellets, clumps, branched filaments and unbranched filaments, as indicated in Figure 1, similarly to other works in literature (Yang et al, 1996;Paul and Thomas, 1998), using a LEICA Q550IW Image Analyser attached to a LEICA DM/LS optical microscope (Pamboukian et al, 2002). The images were acquired with a SONY DXC-950P CCD camera.…”

“…A 20 µL aliquot of the diluted sample was pipetted onto a slide glass, dried and fixed over a Bunsen flame, and stained with methylene blue (0.3 g methylene blue, 30 mL 95 % ethyl alcohol, in 100 mL distilled water) (Yang et al, 1996). For each sample, a minimum of 100 objects was measured and the percentage of each morphological class, in terms of projected area, was determined (Pamboukian et al, 2002) as well as the average clump dimension (D), which represented the major morphological class in all runs. Average clump dimension was defined as the average of the dimensions of the clumps in eight different directions (ferets).…”