Side-chain cleavage and C-20 ketone reduction of hydrocortisone by a natural isolate ofChroococcus dispersus

Abstract

A unicellular cyanobacterium, Chroococcus dispersus (Keissl.) Lemmermann, was isolated from paddy-field and tested in biotransformation experiments of hydrocortisone (compound 1). This strain has not been previously examined for steroid substance modification. Fermentation was carried out in BG-11 medium supplemented with 0.05% substrate at 25 ºC for seven days incubation. The metabolites were chromatographically purified and characterised using spectroscopic methods. The fermentation yielded 11β,17α,20β,21-tetrahydroxypregn-4-en-3-one (compound 2), 11β,17β-dihydroxyandrost-4-en-3,17-dione (compound 3), and 11β-hydroxyandrost-4-en-3,17-dione (compound 4). Bioreaction characteristics observed were 20-ketone reduction for accumulation of compound 2 and side chain degradation of the substrate to give compounds 3 and 4. Time course study showed the accumulation of the product 2 from the second day of the fermentation and product 3 as well as product 4 from the third day. All the metabolites reached their maximum concentration in seven days. Aeration and continuous light or light duration (16/8 hours light/dark) have no effect on the transformation yield. Optimum concentration of the substrate, which gave maximum bioconversion efficiency, was 0.5 mg ml -1 in the transformation experiment. Growth was not influenced by the addition of steroid substrate. Biotransformation was completely inhibited when steroid concentration was above 2.0 mg ml -1 .

Evaluation of antioxidant properties and total phenolic contents of some strains of microalgae

“…Axenic cultures of Anabaena cylindrica, C. vulgaris, Chroococcus dispersus (Ghasemi et al 2007), Fischerella ambigua (Tabatabaei , F. musicola, Microchaete sp., Nostoc ellipsosporum (Moradpour et al 2006), Nostoc muscorum , N. muscorum Agardh, Nostoc piscinale (Gharaei-Fathabad et al 2007;Gharaei-Fathabad et al 2008), Nostoc sp., and Tolypothrix tenuis were prepared. They had been isolated from soil samples in our previous studies with the cooperation of the Department of Biology, ACECR Center, Research Institute of Applied Science, Tehran, Iran.…”

Biotransformation of monoterpenes by immobilized microalgae

“…Analytical methods GC/MS analyses were carried out on a Hewlett-Packard 6890 USA, as described previously (Ghasemi et al 2007). One microliter of each extract and standard chemicals (monoterpene substrates) was injected into a HP-5M capillary column (phenyl methyl siloxan, 25 m×0.25 mm i.d., Hewlett-Packard, USA).…”

Effects of menthone and piperitone on growth, chlorophyll a and beta-carotene production in Dunaliella salina

“…Monoterpenes are biosynthesised secondary metabolites that obtained from plants and microalgae. They are subgroup of terpenoids with anti-protozoan, antimicrobial, disinfectant, antiseptic, wound healing, antiparasitic and anti-cancer properties (Bakkali et al, 2008;Dorman et al, 2000;Ghasemi et al, 2007a;Leal et al, 2013). They are widely used in food industry, clinical practices, cosmetics and agriculture (Burt, 2004, Edris, 2007.…”

“…Menthone and piperitone are the main fractions of Menthapiperita essence with anti-microbial properties and are widely used in fragrance and pharmaceutical industries (Iscan et al, 2002;Kalemba and Kunicka, 2003). Microalgae are microorganisms of multi purposes, with a variety of potential applications in food, environmental biotechnology, chemical convertors and biofuel (Ghasemi et al, 2007b;Ghasemi et al, 2011a;Ghasemi et al, 2008a;Ghasemi et al, 2012;Shaker et al, 2015;Yazdi et al, 2005). Dunaliella salina, is a photosynthetic unicellular green microalga that lacks a rigid wall (Borowitzka, 2013).…”