Lata Agarwal

Microbial production and applications of 1,2-propanediol

Abstract1,2-Propanediol (propylene glycol) is an existing commodity chemical and can be produced from renewable resources using microbes. By virtue of being a natural product, relevant biochemical pathways can be harnessed into fermentation processes to produce 1,2-propanediol. In the present review, the chemical process and different biological strategies for the production of 1,2-propanediol are reviewed and compared with the potentials and limitations of all processes. For the successful commercial production of this diol, it is necessary to establish the metabolic pathways and production hosts (microorganisms), which are capable of delivering final product with high yields and volumetric productivity. Three pathways which have been recognized for 1,2-propanediol production are discussed here. In the first, de-oxy sugars like fucose and rhamnose are used as the carbon sources, while in the other route, the glycolytic intermediate-dihydroxyacetonephosphate (DHAP) is used to produce 1,2-propanediol via the formation of methylglyoxal. A new pathway of 1,2-propanediol production by lactic acid degradation under anoxic conditions and the enzymes involved is also discussed. The production of this diol has gained attention because of their newer applications in industries such as polymers, food, pharmaceuticals, textiles, etc. Furthermore, improvement in fermentation technology will permit its uses in other applications. Future prospect in the light of the current research and its potential as a major bulk chemical are discussed.

A cost effective fermentative production of succinic acid from cane molasses and corn steep liquor by Escherichia coli

Aim:  Development and optimization of an efficient and inexpensive medium for succinic acid production by Escherichia coli under anaerobic conditions.

Statistical optimization for tannase production from Aspergillus niger under submerged fermentation.

Statistically based experimental design was employed for the optimization of fermentation conditions for maximum production of enzyme tannase from Aspergillus niger. Central composite rotatable design (CCRD) falling under response surface methodology (RSM) was used. Based on the results of ‘one-at-a-time’ approach in submerged fermentation, the most influencing factors for tannase production from A. niger were concentrations of tannic acid and sodium nitrate, agitation rate and incubation period. Hence, to achieve the maximum yield of tannase, interaction of these factors was studied at optimum production pH of 5.0 by RSM. The optimum values of parameters obtained through RSM were 5% tannic acid, 0.8% sodium nitrate, 5.0 pH, 5 × 107 spores/50mL inoculum density, 150 rpm agitation and incubation period of 48 h which resulted in production of 19.7 UmL−1 of the enzyme. This activity was almost double as compared to the amount obtained by ‘one-at-a-time’ approach (9.8 UmL−1).

Preinoculation with Arbuscular Mycorrhizae Helps Acacia auriculiformis Grow in Degraded Indian Wasteland Soil

Abstract The effect of inoculation of two arbuscular mycorrhizal fungi, Glomus fasciculatum, and G. macrocarpum, alone and in combination, on establishment and growth of Acacia auriculiformis in a wasteland soil was studied under nursery and field conditions. Under nursery conditions, mycorrhiza-colonized seedlings showed significantly higher root shoot dry weights and higher concentrations of phosphorus (P), potassium (K), zinc (Zn), copper (Cu), iron (Fe), and sodium (Na) in shoots of mycorrhizal than nonmycorrhizal seedlings. However, concentration of calcium (Ca) was unchanged. Acacia auriculiformis exhibited a maximal mycorrhizal dependency of 79.6% on dual inoculation. Mycorrhizal dependency differed with AM fungal isolates and age of the plant. Under field conditions, AM colonization of A. auriculiformis enhanced tree survival rates (85%) after transplantation. Arbuscular mycorrhiza-colonized plants showed significant increase in height, biomass production, and girth as compared to nonmycorrhizal plants. In general, all growth parameters were higher on dual inoculation of G. fasciculatum and G. macrocarpum as compared to uninoculated plants under both nursery and field conditions.