Current status and future prospects of using advanced computer-based methods to study bacterial colonial morphology

ABSTRACT

Despite the advancement of recent molecular technologies, culturing is still considered the gold standard for microbial sample analysis. Here we review three different bacterial colony–based screening modalities that provide significant information beyond the simple shape and color of the colony. The plate imaging technique provides numeration and quantitative spectral reflectance information for each colony, while Raman spectroscopic analysis of bacteria colonies relates the Raman-shifted peaks to specific chemical bonding. Finally, the elastic-light-scatter technique provides a volumetric interaction of the whole colony through laser-bacteria interactions, instantly capturing the morphological traits of the colony and allowing quantitative classifications.

Keywords:

• Bacterial colony
• colony count
• raman spectrometry
• elastic light scattering

Financial & competing interests disclosure

This research was supported, in part, by funds from USDA-ARS project number 8072-42000-072-00D in conjunction with the Center for Food Safety Engineering at Purdue University. Authors E Bae, B Rajwa, and JP Robinson declare interests in Doclu LLC which develops the next generation data analysis software for ELS system. The terms of this arrangement have been reviewed and approved by the Purdue University in accordance with its policy on objectivity in research. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Key issues

• Digital plate imaging is an expansion of the traditional colony-count method with more rich and quantitative information on both numeration and pigmentation.

• Raman spectroscopy is a nondestructive method that can provide chemical fingerprints of an intact bacterial colony and that can complement morphology-based methods

• ELS is a volumetric photon-bacteria analysis method that is noninvasive and provides accurate classification with the help of a supervised classification method.

• A key aspect of applying these in a clinical setting is balancing the cost and accuracy of the system.