Current / selected Publication

Current perspective of yellowish-orange pigments from
microorganisms- a review

Claira Arul Aruldass , Laurent Dufosse , Wan Azlina Ahmad.

Natural yellowish-orange pigments are derived from bacteria, yeasts, fungi and microalgae, including
Chryseobacterium, Monascus and Chlorella. The purpose of this review is to provide an overview of these pigments in various aspects towards exploiting them for numerous functions. These pigments are produced in various shades of yellow-orange and categorised as carotenoids, anthraquinones, zeaxanthin, flexirubin and other compounds. They served as alternative colourants to replace hazardous and toxic synthetic pigments. Researchers are in progress to increase the pigment yield by improving the strains genetically, optimising the fermentation process and utilising cheap agro-industrial waste to reduce the production cost. Yellowish-orange pigments are applied in food, pharmaceuticals, cosmetics and textile industries. This review summarises the current technology status and challenges, economics, biosynthesis of pigment, novel strategies for production of yellowish-orange pigments, biological properties of pigments and metabolic engineering of microorganism with a focus on applications of pigments in food, pharmaceutical, dyeing industries as well as on other applications.

Antibacterial mode of action of violacein from Chromobacterium violaceum UTM5 against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA)

Claira Arul Aruldass,  Santhana Raj Louis Masalamany, Chidambaram Kulandaisamy Venil & Wan Azlina Ahmad

Violacein, violet pigment produced by  Chromobacterium violaceum, has attracted much attention recently due to its pharmacological properties including antibacterial activity. The present study investigated possible antibacterial mode of action of violacein from C. violaceum UTM5 against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) strains. Violet fraction was obtained by cultivating C. violaceum UTM5 in liquid pineapple waste medium, extracted, and fractionated using ethyl acetate and vacuum liquid chromatography technique. Violacein was quantified as major compound in violet fraction using HPLC analysis. Violet fraction displayed bacteriostatic activity against S. aureus ATCC 29213 and methicillin-resistant S. aureus ATCC 43300 with minimum inhibitory concentration (MIC) of 3.9 μg/mL. Fluorescence dyes for membrane damage and scanning electron microscopic analysis confirmed the inhibitory effect by disruption on membrane integrity, morphological alternations, and rupture of the cell membranes of both strains. Transmission electron microscopic analysis showed membrane damage, mesosome formation, and leakage of intracellular constituents of both bacterial strains. Mode of action
of violet fraction on the cell membrane integrity of both strains was shown by release of protein, K+, and extracellular adenosine 5′-triphosphate (ATP) with 110.5 μg/mL, 2.34 μg/ mL, and 87.24 ng/μL, respectively, at 48 h of incubation.