Selection of culture media for the production of carotenoids with antioxidant activity by Rhodotorula glutinis

Rhodotorula glutinis is an aerobic yeast with particular metabolic characteristic that can produce large amount of carotenoids during the stationary growth phase. Carotenoid is an important natural pigment with antioxidant properties, which is used in food, pharmaceutical and cosmetics industry as additives. The aim of this work is to study the production of carotenoid with antioxidant activity by R.glutinis R12 in different media conditions. The selected strain was cultivated in three different culture media such as YM broth, Basal and MS3 medium at 28°C for 72–120 hours. After fermentation, cells were harvested by centrifugation and freeze-dried. Carotenoid from the biomass was extracted as a mixture of DMSO, acetone and petroleum ether with a ratio of 1:2:2 and cells were ruptured using ultrasonic wave. The carotenoid content in the supernatant was measured by spectrophotometric method. The highest content of carotenoids extracted from R.glutinis R12 was 283.71µg/g dry biomass. The maximum antioxidant activity of carotenoid by DPPH assays were achieved 52.09 ± 0.4% (IC50= 536.02) and at a concentration of 600 µg ml-1. This study revealed that the R.glutinis R12 strain has the ability to produce carotenoid and has shown antioxidant activity in Basal and MS3 medium. For further study, it is necessary to investigate the improvement of carotenoid yield from R.glutinis R12 strains

Problematizing fit and survival: transforming the law of requisite variety through complexity misalignment

The law of requisite variety is widely employed in management theorizing and is linked with core strategy themes such as contingency and fit. We reflect upon requisite variety as an archetypal borrowed concept. We contrast its premises with insights from the institutional literature and commitment literature, draw propositions that set boundaries to its applicability, and review the ramifications of what we call “complexity misalignment.” In this way we contradict foundational assumptions of the law, problematize adaptation- and survival-centric views of strategizing, and theorize the role of human agency in variously complex regimes