Sustainable Synthesis and Characterization of Extracellular Bio-colorants from Metapseudomonas lalkuanensis

Abstract

The escalating environmental and health risks associated with recalcitrant synthetic dyes
have catalysed a shift toward sustainable, biodegradable alternative. This study explores the potential
of indigenous chromogenic bacteria as biological factories for natural pigment production. Through a
systematic screening of soil and sewage samples from diverse ecological niches in Akola, 14 robust
pigment-producing bacterial strains were isolated.
Critical growth parameters were optimized to enhance metabolic yield, identifying a
temperature of 37°C, a pH of 7.5, and a 0.5% NaCl concentration over a 48-hour incubation period as
the physiological optima for maximum pigmentation. Four distinct isolates—GS3B (Orange), SS4A
(Yellow), WS2 (Green), and SS3A (Pink)—were selected for detailed characterization. Molecular
identification via 16S rRNA gene sequencing confirmed isolate WS2 as Metapseudomonas
lalkuanensis.
Notably, while most strains produced intracellular pigments, M. lalkuanensis demonstrated
high-efficiency extracellular secretion. The green pigment from this strain was recovered via solvent
extraction and successfully validated as a viable bio-dye for textile applications. These results
underscore the feasibility of utilizing local microbial biodiversity for the scalable production of eco-
friendly colorants, offering a promising path toward greener industrial dyeing processes.