Importance of Selecting Appropriate Wavelength, While Quantifying Growth and Production of Quorum Sensing Regulated Pigments in Bacteria

Abstract

This work indicates that while working with pigmented bacteria, it is important to pay attention to the absorption spectrum of the pigment(s) involved, and also to dilute the dense bacterial suspensions appropriately prior to measuring optical density, so as to avoid any major deviation of OD from the proportionality to the cell density. Besides presenting the experimental data in this paper, patents regarding measurement of cell growth, as well as those indicating the potential of commercialization of various aspects of QS research have been mentioned.

Influence of a mono-frequency sound on bacteria can be a function of the sound-level

“…At the end of incubation, after quantifying the cell density at 764 nm (Joshi et al, 2016), the C. violaceum culture tubes were subjected to extraction of the pigment violacein (Choo et al, 2006). Briefly, 1 mL of the culture broth was centrifuged (REMI CPR-24 PLUS) at 12,000 rpm (13,520 g) for 15 min at 25ºC, and the resulting supernatant was discarded.…”

Anti-infective efficacy of Psidium guajava L. leaves against certain pathogenic bacteria

“…To have some insight into the mode of action of GLE, we incubated all the five test bacteria with GLE to investigate whether it affects bacterial growth and/or quorum-sensing (QS) regulated pigment production (a marker trait). Bacterial cell density and pigment production were quantified as earlier described by us (Joshi et al, 2016;Patel et al, 2018). At least one concentration of GLE was found to modulate pigment production in all the four pigmented bacteria (Figure 3; Dataset 1: Underlying data).…”

“…DMSO (0.5%v/v) and GLE at tested concentrations showed no toxicity towards C. elegans. Bacterial cell density and pigment production were quantified as earlier described by us (Joshi et al, 2016). Bacterial growth was measured as OD 764 for the four pigmented bacteria, while for S. pyogenes OD 660 was used.…”

Investigating the influence of extraction methodology, and certain other experimental parameters on bacterial response to selected quorum-modulatory plant extracts

“…Effect of test extracts on bacterial growth and production of quorum sensing (QS)-regulated pigments were assessed using the methods described by us previously [3]. Appropriate vehicle control containing DMSO was also included in the experiment, along with abiotic control (containing extract, but no inoculum).…”