Formation of mixed crystals in microbial conversion of sterols and steroids

Goetschel, Ruth; Bar, Raphael

doi:10.1016/0141-0229(92)90138-e

Cited by 49 publications

(22 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This may be due to the toxicity of the substrate on the activity of the microorganism. The same phenomena were discussed by Constantinides [39], Goetschel and Bar [40] and Arinbasarova [41].…”

Section: Discussionsupporting

confidence: 50%

Studies on the microbial transformation of androst-1,4-dien-3,17-dione with Acremonium strictum

Faramarzi

Yazdi

Jahandar

et al. 2006

J IND MICROBIOL BIOTECHNOL

View full text Add to dashboard Cite

The strain of Acremonium strictum PTCC 5282 was applied to investigate the biotransformation of androst-1,4-dien-3,17-dione (I; ADD). Microbial products obtained were purified by preparative TLC and the pure metabolites were characterized on the basis of their spectroscopic features (13C NMR, 1H NMR, FTIR, MS) and physical constants (melting points and optical rotations). The 15 alpha-Hydroxyandrost-1,4-dien-3,17-dione (II), 17 beta-hydroxyandrost-1,4-dien-3-one (III), androst-4-en-3,17-dione (IV; AD), 15 alpha-hydroxyandrost-4-en-3,17-dione (V), 15 alpha,17 beta-dihydroxyandrost-1,4-dien-3-one (VI) and testosterone (VII) were produced during this fermentation. Formation of the 15 alpha,17 beta-dihydroxy derivative of ADD is reported for the first time during steroid biotransformation. The bioconversion reactions observed were 1,2-hydrogenation, 15 alpha-hydroxylation and 17-ketone reduction. From the time course profile of this biotransformation, ketone reduction and 1,2-hydrogenation were observed from the first day of fermentation while 15 alpha-hydroxylation occurred from the third day. Optimum concentration of the substrate, which gave the maximum bioconversion efficiency, was 0.5 mg ml(-1) in one batch. The highest yield of the microbial products recorded in this work was achieved within the pH range 6.5-7.3 and at the temperature of 27 degrees C.

show abstract

Section: Discussionsupporting

confidence: 50%

Studies on the microbial transformation of androst-1,4-dien-3,17-dione with Acremonium strictum

Faramarzi

Yazdi

Jahandar

et al. 2006

J IND MICROBIOL BIOTECHNOL

View full text Add to dashboard Cite

show abstract

“…The histogram also shows that the conversion percentage measured at 30, 40, and 50 mg/50 mL medium at 24 hours becomes lower (48.13, 10.94, and 6.43%) compared with the conversion percentage measured at 10 and 20 mg at the same time (58.33 and 50.49%), respectively. This is due to that the higher concentration of substrate may block the pores of the hydrogel and also hinder the exchange of oxygen and substrate diffusion through the hydrogel [2, 22, 23, 24]. In general, the conversion percentages measured at 10, 20, 30, 40, and 50 mg/50 mL medium at 18 hours were higher than those obtained at 24 hours.…”

Section: Resultsmentioning

confidence: 99%

“…But the immobilized cells reused more than 6 times highly reduce the prednisolone yield percentage as shown in the histogram up to the 9th cycle. From the above results, we concluded that the cells probably grow in the gel so that the prednisolone yield percentage gradually increases [7, 24]. The repeated use of immobilized cells after the 4th cycle gradually decreases the prednisolone yield percentage and its productivity to (68.8–31.2%) and (3.8–1.7 mg/L/h), respectively, and this may be due to the lyses of the cells, and thus the density of the immobilized cells becomes lower and so led to lower in the cells multiplication and so decreases in the activity of the Δ′-dehydrogenase [29].…”

Section: Resultsmentioning

confidence: 99%

Production of Prednisolone by Pseudomonas oleovorans Cells Incorporated Into PVP/PEO Radiation Crosslinked Hydrogels

El-Hady

El‐Rehim

2004

BioMed Research International

View full text Add to dashboard Cite

In order to rise the yield of prednisolone from hydrocortisone, the Pseudomonas oleovorans cells were entrapped into radiation crosslinked poly (vinyl pyrrolidone)/poly(ethylene oxide) (PVP/PEO) hydrogel of different gel contents. The factors affecting the gel content and swelling behavior of the polymeric gel, such as polymer composition, polymer blend concentration, and irradiation doses, were investigated. The formation of gels having a good strength with the ability to retain a desirable amount of water in their three-dimensional network can be achieved by using PVP/PEO copolymer of composition (90 : 10) and concentration of 15% prepared at 20 kGy irradiation dose. At these conditions the prepared hydrogel is considered the most favorable one that gave the highest hydrocortisone bioconversion and prednisolone yield, 81% and 62.8%, respectively. The improvement of prednisolone yield was also achieved by increasing substrate concentration. Maximum hydrocortisone bioconversion (86.44) was obtained at 18 hours by using substrate concentration of 30 mg. Reusability of immobilized Pseudomonas oleovorans entrapped into PVP/PEO copolymer hydrogel was studied. The results indicated that the transformation capacity of hydrocortisone to prednisolone highly increased by the repeated use of copolymer for 4 times. This was accompanied by an increase in prednisolone yield to 89% and the bioconversion of hydrocortisone was 98.8%.

show abstract

“…Phytosterols are more hydrophobic, their water solubility usually being no more than 1 μM. The poor solubility of phytosterols seriously retards their bioavailability because of inadequate mass transfer (Goetschel & Bar, 1992;Phase & Patil, 1994;Malaviya & Gomes, 2008). Many efforts have been carried out to improve the dispersity and dissolubility of phytosterols in reaction media.…”

Section: Low Water Solubility and Adaptive Mechanismsmentioning

confidence: 99%

“…The mechanism of sterol uptake by microbial cells has already been demonstrated: during the transformation process, microbial cells adhere to the surfaces of sterol particles, forming stable agglomerates. Sterol uptake takes place via the direct contact between the cells and the sterol particles (Atrat, et al, 1991;Goetschel & Bar, 1992;Fernandes, et al, 2003). This is an adaptive mechanism that allows microorganisms to use minimally water-soluble hydrocarbons as carbon sources.…”

Section: Low Water Solubility and Adaptive Mechanismsmentioning

confidence: 99%