title: Evaluation of the Relationship between the Incubation Time and Carotenoid Production in Rhodotorula Slooffiae and R. Mucilaginosa Isolated from Leather Tanning Wastewater .
abstract: OBJECTIVE
  Carotenoids which are naturally synthesized by fungi such as yeasts can act as an antioxidant which is closely related to their ability to decrease the risk of a variety of degenerative diseases. In recent years, the increase of demand for carotenoids obtained from natural sources has promoted major efforts to improve carotenoid production from biological sources such as pigmented yeasts. The aim of this study was comparing incubation time and carotenoid production in Rhodotorula slooffiae and R. mucilaginosa isolated from leather tanning wastewater.
  
  
  METHODS
  To isolate the carotenoid pigment, cells were suspended in acetone and broken using a homogenizer, followed by centrifugation and separation of supernatant. In order to study the effect of incubation time, samples were held at 30 ˚С in a shaker at 150 rpm for 24, 48, 72, 96, and 120 hr. For analytical evaluation, pigments were measured spectrophotometrically at 450 nm using the extinction coefficient E(1%) 450=2500.
  
  
  RESULTS
  The results showed that the content of total carotenoid in R. slooffiae was the highest when samples were incubated for 72 hr. Overall, R. mucilaginosa had more potential to produce carotenoid. The best incubation periods for R. slooffiae and R. mucilaginosa were 72 hr and 48 hr, respectively.
  
  
  CONCLUSIONS
  It seemed that the maximum rate of total carotenoid was not directly associated with the maximum amount of cell biomass and the type of carotenoid and their relative amount may vary depending on genus of yeast.
authors.affiliation: Department of Biology, Faculty of Science, Alzahra University, Tehran, Iran.
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Sadat Naghavi
authors.affiliation: Department of Biology, Faculty of Science, Alzahra University, Tehran, Iran.
authors.forename: Parichehr
authors.initials: P
authors.lastname: Hanachi
authors.affiliation: Department of Biology, Faculty of Science, Alzahra University, Tehran, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Soudi
authors.affiliation: Department of Biology, Faculty of Science, Alzahra University, Tehran, Iran.
authors.forename: Azra
authors.initials: A
authors.lastname: Saboora
authors.affiliation: Department of Biology, Faculty of Science, Alzahra University, Tehran, Iran.
authors.forename: Atefeh
authors.initials: A
authors.lastname: Ghorbani
keywords: Antioxidant; Carotenoid; Incubation time; Rhodotorula Spectrophotometry