Good Example Of Essay On Biotechnology: Microbial Transformation Of Steroids

The technological advancement has introduced numerous achievements in the field of biotechnology. Microbial transformation or biotransformation is the phenomenon where living organisms are used in modifying materials that are not frequently used for growth (Donova and Egorova). Apart from animal cells, plant tissues and enzymes, microbial transformation is associated with the reactions under biotransformation. A substance can be transformed into another product through microbial action on the substrate. Studies reported that the utilization of biotechnology in the formulation of steroids was introduced in the year 1952. Murray and Peterson developed 1 lα-hydroxylation using Rhizopus and utilized it effectively in steroid drugs (Mahato and Garai 332). This development paved a path for further development of novel steroids by microbial transformation. There has been an increased number of chemists who employed microorganisms in carrying out desired changes in the organic molecules. This essay delineates on microbial steroid conversions, materials and primary reactions involved in functioning of steroids using microbes.
Ismail has reported that the intestinal flora of the rats synthesized the steroid metabolizing enzymes that are not present in the mammalian tissues. It has also been discovered that Endophytes exist in abundance in the tropical rainforests. Endophytes encompass the parasitic plant organisms that live within the body of its host. In fact, microbial transformation by the endophytes has been under study since centuries ago. This involves a scenario where a compound is modified into another compound through the use of green synthesis other than using chemical synthesis (Ismail).
There are numerous chemical reactions that are carried out by the microorganisms including condensation, demecthylation, dehydration, racemisation, phosphorylation, deamination, amination, decarboxylation, reduction and oxidation, as well as hydrolysis. It is imperative to take a look at these basic steps and reactions involved in transformation. Oxidation involves adding oxygen to a molecule that can remove hydrogen from a molecule. Decarboxylation is a phenomenon when carbon oxide is eliminated from the molecule. Deamination reaction involves removing amino groups from a molecule and amination encompasses the reactions when the amino group is grafted or introduced on a molecule. With Phosphorylation reaction, a phosphate ester is added directly to a molecule. Racemisation occurs as a result of converting optically active compounds into enantiomers. Dehydration is a reaction involving water elimination from a molecule while demecthylation is a reaction used for elimination of a methyl group from a molecule. Hydroxylation mechanism is achieved at low cost by steroid industry at commercial scale. The studies show that further research is in process to make this mechanism more cost effective (Bragin et al. 41-53; Ismail).
Moreover, there are also several groups of steroids, and this includes hormonal steroids, steroid alkaloids, sapogenins, ecdysteroids, cucurbitacins, cardenolides, bufadienolides, brassinosteroids and sterols. These hormones and steroids are in use for numerous treatments including cancer, inflammatory diseases, androgenic, progestational and so forth (Mahato and Garai 332-34). The chemical modifications of the compound structures is usually done through chemical pathways of synthesizing. However, this method generates waste products or harmful residues that might bring harm to other living creatures and the environment. Hence, numerous benefits can be obtained from the microbial transformations. With microbial transformation, it is possible to operate at ambient temperatures and atmospheric pressure. This also performs at about neutral pH, but chemical transformations often require extreme conditions that are not environmentally friendly. The extreme temperatures, pressure and pH may harm the working environment in the particular areas and the community surrounding the area. Most crucial is that biocatalysts are reaction specific, region-specific and enantioner-specific (Bragin et al. 41-53; Ismail).
The purpose of using biotransformation is due the ability of microorganisms such as bacteria and fungi to produce large quantities of biomass and a variety of various enzymes within a short time. They possess largest surface-to-volume ratio, and this allows them in maximising their metabolic rates. This is because the high exchange of metabolites and molecules through their surface. The incorporation of the right cultivation conditions facilitate in the exponential growth of microorganisms (Ghisalba, Meyer and Wohlgemuth). In addition, the evident advantages of C19 and C22 precursors’ microbial production from the phytosterols include environmental friendly, shorter process flows and the low-cost processes.
Apart from existing benefits, there are many challenges prevailing in microbial transformation. The inherent challenge of biotransformation processes to grow is the overcoming of the existence of the well-developed traditional technology. In most of the cases, unavailability of financial incentive to implement a new process in the presence of the renowned old process is a major obstacle. The expertise are obligatory in enzyme engineering, immobilisation techniques and recombinant DNA technology. This has the implication of recruiting the personnel with this expertise (Ismail).
Donova and Egorova reviewed sapogenins as a raw material and reported its significance in the steroid industry as a natural steroid. This is in commercial use, and it involves chemical modification of the diosgenin to 16-dehydropregnenolone acetate that is followed by the further synthesis to pharmaceutical steroids (Donova and Egorova 1423–1447; Hanson). Through microbial transformation, diosgenin can produce new steroids that are useful for therapeutic action. Chemical conversions of the sapogeninins to the valuable steroids has got various shortcomings. It includes the exhaustion of the wild plant resources, waste of the land resources, multistep syntheses and higher costs (Hanson; Wang, Yao and Wei).
Hanson mentioned that Diosgenin and Solasodin proved its effectiveness and remained the major raw materials in the industrial production of the steroid in most countries. The alternative starting materials for the steroid industry include natural sterols, more especially, steroid 3B-alcohols. Sterols are very important components of the cell membranes, and they play a significant role in the cell membrane fluidity, the cell proliferation and differentiation. The animal sterol includes Cholesterol (1) while the abundant sterols in plants are brassicosterol, campesterol, stigmasterol (III) and sitosterol (II). (Hanson; Ghisalba, Meyer and Wohlgemuth 1-18).
Human health and life is also associated with sexual functioning. The key intermediates that are microbially produced to date from the sterols include the C19 steroids such as testosterone (VII) and boldenone (VIII). Egorova et al. reported that testosterone is vital in the androgen steroids. Natural sterol are commonly used in the production of testosterone due its low cost and abundance. There are a numerous ways to obtain testosterone from sterols including multistep chemical synthesis, androstadienedione and intermediate androstenedione. Androstadienedione. They contain the microbial transformation of sterol to AD/ADD using rapid growing saprophytic mycobacteria, or other associated microorganisms having blocked steroid nucleus with enzymes. The development of AD or ADD by employing strains is capable of cleaving sterol side chain like Mycobacteriumspp, Rhodococcus erythropolis and so forth. The conversion of AD or ADD to testosterone can be carried out using microbial transformation. They studied a one-step biotechnological process that depended on the microbial conversion of sterols to testosterone by utilizing strains having the capability of both sterol side chains and 17 β-reducing of 3,17-diketoandrostene. They used 1(2)-dehydrogenase technique like Mycobacteriumspp and Lactobacillus bulgaricus because bacterial strains may be blocked in 9 β –hydroxylase. They concluded that the use of ADD facilitated to attain testosterone from sitosterol in a one-step biotechnological operation (Bragin et al. 41-53; Egorova et al. 198- 203).
Donova, Egorova and Nikolayeva also opined that there is an increased demand of steroid pharmaceuticals and 17β-hydroxy- and 17-oxosteroids is of significant importance. There is the probability of reversible microbial reaction in this particular steroid that is related to the existing similarity of structure and function of the microorganisms. They pointed out the prevalence of strong bond between the enzyme and 1(2)-dehydrogenase, 3β-hydroxysteroid dehydrogenase and 1-ene-reductase regarding Mycobacterium spp. The mammalian tissues and associated signaling system of enzyme need further attention due to the importance of human physiology. 17 β-OH SDHs can play an important role to fight the disease like cancer, Alzheimer disease and osteoporosis issue (Donova, Egorova and Nikolayeva 2253-2262). .
In addition, C22 steroids of the pregnane series such as the 20-hydroxymethyl pregna-4-en-3-one (XIII), 20-carboxy-pregna-4-en-3-one and their respective 1-dehydro and 9ahydroxy analogs are few names to mention. Egorova et al. also mentioned that ADD and AD are the most demanded intermediates. These are required for the commercial production of mineralocorticoids, corticosteroids, oral contraceptives and other pharmaceutical steroids. The market size of ADD/AD is evaluated to be above US$ 1 billion annually (Egorova et al. 198-203; Mahato and Garai 332-345).
The production of boldenone (VIII) from phytosterols is reported to involve two steps through the intermediate obtained from AD using the Mycobacterium followed by the 1-dehydrogenation of the AD by Fusarium sp. Dovbnya, Egorova and Donova conducted a study and demonstrated the probability of a single-step production of the derived androst-5 from 3-substituted ergosterol. They mentioned that side-chain in the process of multi-enzyme involved 14 types of reactions to complete the oxidation. More so, the particular enzymes can be incorporated using a derivative of oligoisopren or sterols. This intermediate is vital among the crucial precursors for the synthesis of the vitamin D derivatives (Donova and Egorova 1423–1447; Dovbnya, Egorova and Donova 653-658).
Apart from the C19 steroids, the valuable derivatives of 23, 24-dinorcholane was obtained by microbial activity from the sterols. These compounds are the vital precursors for the synthesis of corticosteroid. For instance, 9a-hydroxy-C22 steroids can be converted to C21 corticosteroids by the oxidative decarboxylation. Donova and Egorova mentioned that most of the microbial stains reported so far are linked with biocatalysts of the sterol bioconversions. These stains include Rhodococcus spp, Pseudomonas spp., Brevibacterium spp. and Arthrobacter spp but they necessitate the addition of inhibitors to curb the steroid nucleus degradation (Donova and Egorova 1423–1447).
Oxidation of sterols by Actinobacteria is of significance importance and all enzymes involved in the oxidation of sterols have not been fully identified. The degradation of the sterols by the actinobacteria involves the three major processes that include steroid nucleus oxidation, elimination of aliphatic side chain at C17 and the sterol uptake. Sterol uptake mechanism by the actinobacteria includes the direct contact of the cell surface with the hydrophobic sterol particles. The cells adhere to the sterol particles and then gradually embed into them. The bioemulsifiers or biosurfactants produced by the actinobacteria extracellularly increases the substrate bioavailability (Wang, Yao and Wei).
According to Wang, Yao and Wei, there are few important initial steps involved in sterol core oxidation. The sterols biotransformation is initiated by the modification of 3ß-ol-5-ene- to 3-oxo-4-ene moiety. The cholesterol oxidase (3ß-hydroxysteroid oxidase) role in this process has been evident. The oleaginous microorganisms are found to be of commercial interest since they reduce organic wastes to a manageable size. They transform the low-value substrates into high-value products like the SCO, which utilize the wastes. The microbial oils are efficient and cheaper source of the poly-saturated fatty acids, which have nutraceutical and pharmaceutical significance. The bacteria associated with the large number of aquatic organisms have been discovered to emerge the better source of the highly pure PUFA oils than the fungal and fish oils (Wang, Yao and Wei).
Microbial production of fats and oil that obtained from the microbial sources are structurally similar to edible oils. The oleaginous molds are the common sources of the microbial fats and oils. In an oleaginous microorganism, fats and oil accumulation begins when the nitrogen depletes. Contrarily, there exists excess of the carbon source like glucose in the growth medium. Some types of yeast have the ability to accumulate lipid between 40% and 70 % of their biomass. These yeasts include Lipomyces starkeyi, Rhodotorula spp and Cryptococcus curvatus. The oil from moulds normally contains both short chains (C8-C12) and the long chain fatty acids (C22-C24). The fungal lipids comprise plenty of the linolenic acid, polyunsaturated fatty acids and oleic acid.
Moreover, animals and plants have been natural sources of fragrances and the flavours for ages. Man made use of microbial systems earliest in a bid to impart new aromas to fermentation products such as cheese, wine and beer. Coumarin and Vanillin were the very first flavour and fragrance compounds that are widely used in pharmaceutical formulations, detergents, cosmetic, beverage and food. There are two categories of fragrances and flavours including the nature- identical and natural. Natural flavours are made from enzymatic or microbial processes. The chemically synthesized fragrances or flavours are called ‘nature-identical’. The ‘natural’ flavours are produced either through de novo synthesis in plants or microbes or by single-step natural substrates biotransformation by plant cells or microbes or enzymes. In de novo synthesis, the microbes transform the nitrogen or carbon compounds into the flavour molecules (Wang, Yao and Wei).
The gums and polysaccharides are used as stabilizers and thickeners in pharmaceutical and food preparations known as gelling agents. They are derived from microbes and plants. The gums and polysaccharides are obtained from algal and plant sources that need high skilled manpower for their collection. The seasonal fluctuations largely affect the yield and quality of the product. The microbial polysaccharides are produced through fermentation by the selected microbes in stirred tank fermenters (Ismail).
Conclusively, this essay has exhibited the significance of the microbial transformation of the steroids. It is worth noting that the chemical production in industries normally involves chemical reactions that lead to the production of substances that are toxic in nature and need extreme conditions. The human beings working in such environments are exposed to an environment, and human exposure should be avoided. Therefore, biotransformation of steroids is a good alternative. It is environmentally friendly and does not expose the human beings working in these areas to extreme conditions such as very high temperatures. This is a natural process that is very effective and can be incorporated for a successful process. Microbial steroid transformation is a cheaper process compared to chemical production.
The microbial steroid transformation also has its side effects. This includes the need of personnel who are well endowed with the knowledge of microbial steroid transformation. It is not easy to get such personnel and very expensive to pay. The chemical synthesis of steroids is the well-known traditional way of synthesizing steroids. Therefore, it becomes a hurdle to adopting the new way of biotransformation at the expense of the tested chemical means. The technological advancement has potential to develop the innovations associated with microbial transformations regarding steroids. It will provide a new boost in the field of biotechnology.

Work Cited

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