Furthermore, interest has grown following molecular engineering in order to modify
well-investigated microbes (i.e. Escherichia coli and Saccharomyces cerevisiae)
into bioenergy cell plants. This could be achieved by initiating an ester synthesizing
route by directly esterifying the bioethanol with acyl-moieties of coenzyme A with
the potential to result in the immediate product of fatty acid ethyl esters (FAEEs).
2.4.3 Yeast and Fungi
Yeasts and fungi are also the suitable oil-producing microorganisms that accumulate
lipids rich in polyunsaturated fatty acids (oleic acids, linoleic acids) together with
frequently found other fatty acids (palmitic or palmitoleic acids). Some major
oleaginous yeast like Rhodosporidium, Rhodotorula, Cryptococcus, Candida,
Lipomyces, etc. are utilized for biodiesel production as they accumulate intracellular
lipids and has many advantages over other renewable sources like high productivity
(up to 65% of cellular dry weight) and less affected by seasonal variations for
growth.
Similarly, some species of fungi are also capable of producing a great amount of
lipids (approximately 70%) that includes Humicolalanuginosa and
Mucorcircinelloides species. Various procedures are followed to form fungal esters
and resulted in the formation of FAME that can be utilized as biodiesel. Thus, yeasts
and fungi seem to be the potential alternative non-conventional source of energy
(Nigam and Singh 2011; Dahman et al. 2019; Meng et al. 2009; Khan et al. 2020).
2.5 Bioethanol
Bioethanol, an important source of fuel, is produced using plant material or food
crops containing large amounts of starch and sugars, such as corn, potato, sugarcane,
and cassava. Ethanol is dominating the biofuel industry with an advantage of higher
octane number and similar energy content and so serves as the most promising
alternatives as a transportation fuel. It is sometimes combined with gasoline for fuel
production or replaces gasoline to reduce carbon dioxide emission. It causes reduced
emissions of toxic gases like sulphur oxide, carbon monoxide, nitric oxide, etc. due
to low-temperature combustion as oxygen is present in its molecular form. Therefore, blending can significantly reduce greenhouse gas emissions.
2.5.1 Substrates for Bioethanol Production
There are several feedstocks which are utilized for bioethanol production, such as
common crops like sugarcane, sugar beet, sorghum, etc.; and starchy feedstocks like
44
N. Jaiswal et al.
well-investigated microbes (i.e. Escherichia coli and Saccharomyces cerevisiae)
into bioenergy cell plants. This could be achieved by initiating an ester synthesizing
route by directly esterifying the bioethanol with acyl-moieties of coenzyme A with
the potential to result in the immediate product of fatty acid ethyl esters (FAEEs).
2.4.3 Yeast and Fungi
Yeasts and fungi are also the suitable oil-producing microorganisms that accumulate
lipids rich in polyunsaturated fatty acids (oleic acids, linoleic acids) together with
frequently found other fatty acids (palmitic or palmitoleic acids). Some major
oleaginous yeast like Rhodosporidium, Rhodotorula, Cryptococcus, Candida,
Lipomyces, etc. are utilized for biodiesel production as they accumulate intracellular
lipids and has many advantages over other renewable sources like high productivity
(up to 65% of cellular dry weight) and less affected by seasonal variations for
growth.
Similarly, some species of fungi are also capable of producing a great amount of
lipids (approximately 70%) that includes Humicolalanuginosa and
Mucorcircinelloides species. Various procedures are followed to form fungal esters
and resulted in the formation of FAME that can be utilized as biodiesel. Thus, yeasts
and fungi seem to be the potential alternative non-conventional source of energy
(Nigam and Singh 2011; Dahman et al. 2019; Meng et al. 2009; Khan et al. 2020).
2.5 Bioethanol
Bioethanol, an important source of fuel, is produced using plant material or food
crops containing large amounts of starch and sugars, such as corn, potato, sugarcane,
and cassava. Ethanol is dominating the biofuel industry with an advantage of higher
octane number and similar energy content and so serves as the most promising
alternatives as a transportation fuel. It is sometimes combined with gasoline for fuel
production or replaces gasoline to reduce carbon dioxide emission. It causes reduced
emissions of toxic gases like sulphur oxide, carbon monoxide, nitric oxide, etc. due
to low-temperature combustion as oxygen is present in its molecular form. Therefore, blending can significantly reduce greenhouse gas emissions.
2.5.1 Substrates for Bioethanol Production
There are several feedstocks which are utilized for bioethanol production, such as
common crops like sugarcane, sugar beet, sorghum, etc.; and starchy feedstocks like
44
N. Jaiswal et al.