Antioxidant activity and β-carotene production of extracts from Bacillus infantis

Bang Hong Lam, Bui Thanh Phu, Nguyen Le Thanh Đat, Huynh Nguyen Nhu Ngoc, Truong De and Nguyen Minh
Chon*

Food and Biotechnology Institute, Cantho University, Vietnam

Carotenoids are the natural pigments in plants, they are also found in the microorganism. Carotenoids play a vital
role in protecting cell membranes against high temperatures, intensive UV, and other oxidation agents. Bacillus is
a big genus of Gram-positive and rod-shaped bacteria. They were known as carotenoid-producing bacteria. In this
study, many Bacillus samples were collected at the seashore in Kien Giang province of Vietnam and Bacillus infantis
was used to examine the antioxidant activity and β-carotene production of its extract. DPPH (2,2-diphenyl-1-
picrylhydrazyl) radical scavenging assay and reducing power assay (reducing Fe³⁺ ions) were used. The result of
the DPPH assay showed that the carotenoid extract could scavenge DPPH radical. Additionally, the crude
carotenoid extract showed antioxidant activity in reducing ferric ions (Fe³⁺). To identify β-carotene from Bacillus
infantis, the pigments from Bacillus biomass were extracted in the mixture of methanol and chloroform (with a ratio
of 1:2 of v/v). The extracted solution was examined by the spectrophotometer to recognize the maximum
absorbance wavelength of β-carotene from 400 to 600 nm. The pigment sample was separated by a silica gel glass
chromatography column and carotenoids were identified by HPLC-MS. β-carotene which is the yellow-orange
compound with the maximum absorbance at 454 – 455 nm, the molecular ion [M+H]⁺ is 537.39, and the ion fragment
[M-92] is 444.33. The results showed that Bacillus infantis is a bacterial source for β-carotene and carotenoid
production.

Keywords: Antioxidant, Bacillus, β-carotene, Carotenoid, DPPH, Reducing