Characterization of Pigments from Wild Strains of Rhodotorula
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Date
2011-06-15
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Karnataka Veterinary, Animal and Fisheries Sciences University, Bidar
Abstract
The main criterion for food selection is colour. Some synthetic colours are
detrimental to human health and hence food industry is looking for natural pigment.
Rhodotorula is a carotenoid biosynthetic yeast producing yellow or orange red colonies.
The present study was taken up for characterization of Rhodotorula from various dairy
environmental sources, screening the isolates for pigment production and characterization
of pigment obtained.
Among dairy environmental samples, air sample showed highest count (3.47 log
cfu/min) followed by apple and can milk. Rhodotorula isolates of 11 were from air (3),
apple (4), can milk (2) and yoghurt (2). Identification revealed 3 isolates as Rhodotorula
minuta, while 2 isolates as Rhodotorula acheniorum and 6 as unidentified isolates as they
did not match with identification key.
All the isolates of Rhodotorula were screened for pigment production based on
urea hydrolysis Rhodotorula minuta RAI3; Rhodotorula acheniorum RC2, Rhodotorula
sp RA2, Rhodotorula minuta RY1 were further selected for pigment production isolated
from air, can milk, apple and yoghurt respectively
Sterile synthetic media Malt Yeast Extract Agar (MYEB), coconut water as liquid
media and rice as solid substrate medium were used for extra and intra cellular pigment
production from Rhodotorula minuta RAI3; Rhodotorula acheniorum RC2, Rhodotorula
sp RA2, Rhodotorula minuta RY1. Coconut water and rice media showed maximum
production of extra and intracellular pigment at 300C for 6 days. Among the 4 isolates,
Rhodotorula minuta RAI3 showed maximum extra and intra cellular pigment production
of 2.877μg/g and 4.412 μg/g of dry cell mass respectively.
Lab pasteurization (630C/30min), boiling (1000C/10min) and sterilization
(1210C/15 min) reduced the intensity of extra and intracellular pigment of Rhodotorula
minuta RAI3. The pigment stability was noticed at pH 7 compared to acidic and alkaline
pH. The stability of extra and intracellular pigments was observed both at room
temperature (290C) and refrigeration temperature (40C) upto 15 days of storage. Three
fractions with Rf values of 0.19, 0.65 and 0.84 for extracellular pigment and 0.21, 0.70
and 0.90 for intracellular pigment was noticed in thin layer chromatography with
benzene: petroleum ether (95:5) as mobile phase that may reveal the presence of -
carotene torularhodin and torulene based on their Rf values respectively.
Description
Pg, Thesis
Keywords
Characterization of Pigments from Wild Strains of Rhodotorula