| 1. |
- Ruhal, Rohit, et al.
(author)
-
Improved trehalose production from biodiesel waste using parent and osmotically sensitive mutant of Propionibacterium freudenreichii subsp. shermanii under aerobic conditions
- 2012
-
In: Journal of Industrial Microbiology & Biotechnology. - : Springer. - 1367-5435 .- 1476-5535. ; 39:8, s. 1153-1160
-
Journal article (peer-reviewed)abstract
- Trehalose is an important nutraceutical of wide commercial interest in the food processing industry. Recently, crude glycerol was reported to be suitable for the production of trehalose using a food microbe, Propionibacterium freudenreichii subsp. shermanii, under static flask conditions. Similarly, enhanced trehalose yield was reported in an osmotically sensitive mutant of the same strain under anaerobic conditions. In the present study, an effort was made to achieve higher production of trehalose, propionic acid, and lactic acid using the parent and an osmotically sensitive mutant of P. freudenreichii subsp. shermanii under aeration conditions. Under aeration conditions (200 rpm in shake flasks and 30 % air saturation in a batch reactor), biomass was increased and approximately 98 % of crude glycerol was consumed. In the parent strain, a trehalose titre of 361 mg/l was achieved, whereas in the mutant strain a trehalose titre of 1.3 g/l was produced in shake flask conditions (200 rpm). In the mutant strain, propionic and lactic acid yields of 0.53 and 0.21 g/g of substrate were also achieved with crude glycerol. Similarly, in controlled batch reactor culturing conditions a final trehalose titre of approximately 1.56 g/l was achieved with the mutant strain using crude glycerol as the substrate. Enhanced production of trehalose using P. freudenreichii subsp. shermanii from waste under aeration conditions is reported here. Higher production of trehalose was not due to a higher yield of trehalose but to a higher final biomass concentration.
|
|
| 2. |
- Ruhal, Rohit, et al.
(author)
-
Membrane Separation and Design
- 2012
-
In: Handbook of Food Process Design. - : Blackwell Publishing. - 9781444330113 - 9781444398274 ; , s. 769-788
-
Book chapter (other academic/artistic)
|
|
| 3. |
- Ruhal, Rohit, et al.
(author)
-
Trends in bacterial trehalose metabolism and significant nodes of metabolic pathway in the direction of trehalose accumulation
- 2013
-
In: Microbial Biotechnology. - : Wiley. - 1751-7907 .- 1751-7915. ; 6:5, s. 493-502
-
Journal article (peer-reviewed)abstract
- The current knowledge of trehalose biosynthesis under stress conditions is incomplete and needs further research. Since trehalose finds industrial and pharmaceutical applications, enhanced accumulation of trehalose in bacteria seems advantageous for commercial production. Moreover, physiological role of trehalose is a key to generate stress resistant bacteria by metabolic engineering. Although trehalose biosynthesis requires few metabolites and enzyme reactions, it appears to have a more complex metabolic regulation. Trehalose biosynthesis in bacteria is known through three pathways - OtsAB, TreYZ and TreS. The interconnections of in vivo synthesis of trehalose, glycogen or maltose were most interesting to investigate in recent years. Further, enzymes at different nodes (glucose-6-P, glucose-1-P and NDP-glucose) of metabolic pathways influence enhancement of trehalose accumulation. Most of the study of trehalose biosynthesis was explored in medically significant Mycobacterium, research model Escherichia coli, industrially applicable Corynebacterium and food and probiotic interest Propionibacterium freudenreichii. Therefore, the present review dealt with the trehalose metabolism in these bacteria. In addition, an effort was made to recognize how enzymes at different nodes of metabolic pathway can influence trehalose accumulation.
|
|
| 4. |
- Ruhal, Rohit, et al.
(author)
-
Use of an osmotically sensitive mutant of Propionibacterium freudenreichii subspp. shermanii for the simultaneous productions of organic acids and trehalose from biodiesel waste based crude glycerol
- 2012
-
In: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 109, s. 131-139
-
Journal article (peer-reviewed)abstract
- Recently suitability of crude glycerol for trehalose and propionic acid productions was reported using Propionibacterium freudenreichii subspp. shermanii and it was concluded that presence of KCl in crude glycerol was the probable reason for higher trehalose accumulation with crude glycerol medium. To further improve trehalose production, an osmotic sensitive mutant of this strain (non-viable in medium with 3% NaCl) with higher trehalose yield was isolated. In mutant, trehalose yields achieved with respect to biomass and substrate consumed (391 mg/g of biomass, 90 mg/g of substrate consumed) were three and four times higher, respectively as compared to parent strain when crude glycerol was used as a carbon source. Other major fermentation products obtained were propionic acid (0.42 g/g of substrate consumed) and lactic acid (0.3g/g of substrate consumed). It was also observed that in mutant higher activity of ADP-glucose pyrophosphorylase was probably responsible for higher trehalose accumulation.
|
|
