end) and degrade the cellulose resulting in the formation of two products which is
cellobiose and glucose. The last step in the enzymatic hydrolysis is complete with
the conversion of cellodextrins and cellobiose by the action of enzyme ß-glucosidase
(BGL) (EC 3.2.1.21) and formation of glucose as the end product (Table 2.1)
(Gaurav et al. 2017; Chiaramonti 2011; Blanch 2012; Ephraim et al. 2020;
Srivastava et al. 2020a, b).
2.4 Microbial Production of Biodiesel
Biodiesel is the first-generation liquid biofuel, used alone or blended with diesel up
to 5% (v/v). Production of biodiesel is done through the chemical processes involving trans-esterification of triacylglycerols (from vegetable oil or animal fat) with
alcohols (methanol or ethanol) and leading to the formation of monoalkyl esters of
long chain of fatty acids, namely fatty acid methyl esters (FAMEs) and fatty acid
ethyl esters (FAEEs). Thus, two steps are involved for biodiesel generation,
i.e. extracting oil or lipid and trans-esterification of extracted lipid in the presence
of alcohols. The latter step may require the presence of catalysts.
Table 2.2 Properties of different types of biofuels (Prakash et al. 2016)
Fuel
Gasoline Biobutanol Bioethanol Biodiesel Biomethanol
Energy density (MJ/I)
32–35
29.2
29.2
–
16
Air fuel ratio
14.6
11.1
11.2
–
6.4
Specific energy (MJ/kg air)
2.9
3.6
–
–
3.1
Mileage (%)
100
61–66
83–91
–
–
Research octane number
(RON)
91–99
96
96
–
106
Motor octane number (MON) 81–89
78
78
–
92
Vapour pressure (20
C:hPa) 35–90
58
6.7
–
–
Enthalpy of vaporization
(MJ/kg)
0.36
0.43
0.43
–
1.2
Cetane number
Below
15
12
8
40–55
3
Density (g/mL)
0.81
0.79
0.86
0.80
Auto-ignition temperature
(
C)
257.2
385
434
200–220 470
Lower heating value (MJ/kg) –
35.1
26.8
42.5
19.9
Boiling point (
C)
30–215
117
78.4
300–350 64.5
Flashpoint (
C)
À43
35
12.8
135–150 –
Kinematic viscosity (at 20
C:
mm
2
/s
0.4–0.8
1.5
3.6
–
–
Saturation temperature (
C)
–
20
20
–
20
Saturation pressure (kPa)
–
0.6
5.93
–
11.83
2 Application of Microorganisms for Biofuel Production
39
cellobiose and glucose. The last step in the enzymatic hydrolysis is complete with
the conversion of cellodextrins and cellobiose by the action of enzyme ß-glucosidase
(BGL) (EC 3.2.1.21) and formation of glucose as the end product (Table 2.1)
(Gaurav et al. 2017; Chiaramonti 2011; Blanch 2012; Ephraim et al. 2020;
Srivastava et al. 2020a, b).
2.4 Microbial Production of Biodiesel
Biodiesel is the first-generation liquid biofuel, used alone or blended with diesel up
to 5% (v/v). Production of biodiesel is done through the chemical processes involving trans-esterification of triacylglycerols (from vegetable oil or animal fat) with
alcohols (methanol or ethanol) and leading to the formation of monoalkyl esters of
long chain of fatty acids, namely fatty acid methyl esters (FAMEs) and fatty acid
ethyl esters (FAEEs). Thus, two steps are involved for biodiesel generation,
i.e. extracting oil or lipid and trans-esterification of extracted lipid in the presence
of alcohols. The latter step may require the presence of catalysts.
Table 2.2 Properties of different types of biofuels (Prakash et al. 2016)
Fuel
Gasoline Biobutanol Bioethanol Biodiesel Biomethanol
Energy density (MJ/I)
32–35
29.2
29.2
–
16
Air fuel ratio
14.6
11.1
11.2
–
6.4
Specific energy (MJ/kg air)
2.9
3.6
–
–
3.1
Mileage (%)
100
61–66
83–91
–
–
Research octane number
(RON)
91–99
96
96
–
106
Motor octane number (MON) 81–89
78
78
–
92
Vapour pressure (20
C:hPa) 35–90
58
6.7
–
–
Enthalpy of vaporization
(MJ/kg)
0.36
0.43
0.43
–
1.2
Cetane number
Below
15
12
8
40–55
3
Density (g/mL)
0.81
0.79
0.86
0.80
Auto-ignition temperature
(
C)
257.2
385
434
200–220 470
Lower heating value (MJ/kg) –
35.1
26.8
42.5
19.9
Boiling point (
C)
30–215
117
78.4
300–350 64.5
Flashpoint (
C)
À43
35
12.8
135–150 –
Kinematic viscosity (at 20
C:
mm
2
/s
0.4–0.8
1.5
3.6
–
–
Saturation temperature (
C)
–
20
20
–
20
Saturation pressure (kPa)
–
0.6
5.93
–
11.83
2 Application of Microorganisms for Biofuel Production
39