• Energy Research

In this study, Nocardia lactamdurans NRRL 3802 was explored for the first time for production of cephamycin C by using solid-state fermentation. The effects of various substrates, moisture content, inoculum size, initial pH of culture medium, additional nitrogen source and amino acids were investigated for the maximum production of cephamycin C by N. lactamdurans NRRL 3802 in solid-state fermentation. Subsequently, selected fermentation parameters were further optimized by response surface methodology (RSM). The soybean flour as a substrate with moisture content of 65%, initial pH of culture medium of 6.5 and inoculum size of 10(9)CFU/ml (2 x 10(8)CFU/gds) at 28+/-2 degrees C after 4 days gave maximum production of 15.75+/-0.27 mg/gds of cephamycin C as compared to 8.37+/-0.23 mg/gds before optimization. Effect of 1,3-diaminopropane on cephamycin C production was further studied, which further increased the yield to 27.64+/-0.33 mg/gds.

Fermentation products can chaotropically disorder macromolecular systems and induce oxidative stress, thus inhibiting biofuel production. Recently, the chaotropic activities of ethanol, butanol and vanillin have been quantified (5.93, 37.4, 174kJ kg(-1)m(-1) respectively). Use of low temperatures and/or stabilizing (kosmotropic) substances, and other approaches, can reduce, neutralize or circumvent product-chaotropicity. However, there may be limits to the alcohol concentrations that cells can tolerate; e.g. for ethanol tolerance in the most robust Saccharomyces cerevisiae strains, these are close to both the solubility limit (<25%, w/v ethanol) and the water-activity limit of the most xerotolerant strains (0.880). Nevertheless, knowledge-based strategies to mitigate or neutralize chaotropicity could lead to major improvements in rates of product formation and yields, and also therefore in the economics of biofuel production.

Root biomass of Coleus forskohlii obtained after extraction of forskolin constitutes more than 90% of the raw material rich in carbohydrates that could be used as a substrate for the production of bioethanol. Ethanol production from this waste biomass was optimized in batch and continuous fermentation. The maximum ethanol concentration of 31.32 g/l was obtained with batch fermentation. Continuous production of ethanol was carried out using wood chips immobilized cells of Saccharomyces cerevisiae in packed bed reactor. The maximum ethanol concentration of 34.25 g/l was obtained with nitrogen supplement and aeration as compared to 33.57 g/l without supplement and aeration at 0.1 (1/h) dilution rate showing no effect of aeration and nitrogen at low dilution rate. The maximum ethanol productivity (15.88 g/l h) was obtained at a dilution rate of 1 (1/h) with nitrogen supplement and aeration whereas ethanol productivity (13.48 g/l h) was obtained at a dilution rate of 0.75 (1/h) without nitrogen supplement and aeration showing promising effect of nitrogen and aeration at high dilution rate. Immobilized column reactor was useful for the production of bioethanol, and also suggests efficient utilization of C. forskohlii root biomass for the production of bioethanol.

Ubiquinone (Coenzyme Q10, CoQ10), a yellow-to-orange-colored lipophilic substance having nutraceutical value, was extracted from dried biomass of Pseudomonas diminuta using supercritical carbon dioxide (SC-CO(2)). The effect of different operational parameters (temperature, pressure, and extraction time) and addition of co-solvent on SC-CO(2) extraction of CoQ10 was studied in detail. The solubility parameter of CoQ10, CO(2), and CO(2) with ethanol and methanol as co-solvents was calculated and validated with experimental results. Theoretically, ethanol and methanol had significant effect as co-solvent, and the difference between the two was only marginal. A maximum recovery of 22.33% was obtained using pure SC-CO(2) at 40 °C, 150 bar, and run time of 60 min. Ethanol as co-solvent at 3 mL/g of dried biomass at 40 °C and 150 bar increased the recovery from 22.33 to 68.57%. Further optimization of the extraction conditions by Box-Behnken design effectively increased the recovery to 96.2%. The optimized conditions were a temperature of 38 °C, pressure of 215 bar, and run time of 58 min.

This work investigates the potential of metabolic stimulators, firstly to enhance the production of beta-carotene, and later use of inhibitors of lycopene cyclase so as to accumulate lycopene in the fermentation medium. Various non-ionic surfactants, natural oils, stimulators such as amino-acids, tricarboxylic acid cycle (TCA) intermediates, vitamin A and antibiotics were investigated for improved production of beta-carotene using the zygomycete fungus Blakeslea trispora. Span 20 at 0.2% increased the beta-carotene production from 139 mg/l to 318 mg/l. Examination of the mycelial morphology of the B. trispora with span 20 showed a shorter mycelial length, which allowed a well-dispersed growth of B. trispora. Supplementation of the medium with 1000 ppm vitamin A acetate gave highest concentration of beta-carotene (830+/-6 mg/l). Several chemical inhibitors such as imidazole, pyridine, triethylamine, piperidine, and nicotinic acid were then evaluated to block the biosynthesis at lycopene. Piperidine at 500 ppm gave a 7.76-fold improvement, and produced high titers of lycopene (775+/-5 mg/l) in a medium supplemented with vitamin A acetate.

The biomass obtained after the extraction of forskolin from the roots of Coleus forskohlii was evaluated as a substrate for the production of acetone-butanol-ethanol (ABE). The spent biomass constituting more than 90% of the raw material showed 50–70% carbohydrates with starch and cellulose being the major constituents. This study was undertaken to optimize enzymatic hydrolysis of C. forskohlii roots for maximum release of fermentable sugars and subsequent fermentation to ABE. The root biomass was hydrolyzed using the Stargen® 002 and Accellerase® 1500. Cocktail of both enzymes (16U Stargen® 002 and 60 FPU Accellerase® 1500) could produce 41.2 g/l of total reducing sugars (glucose equivalent to 32.33 g/l). The production of ABE was optimized in a batch fermentation using Clostridium acetobutylicum NCIM 2877. The maximum ABE production using the root hydrolysates was 0.55 g/l. Pretreatment with lime and Amberlite XAD-4 increased the production of total solvent to 5.33 g/l.

This study explored the use of gellan gum as an immobilization matrix for production of cyclosporin A (CyA) by immobilized spores and mycelia of Tolypocladium inflatum MTCC 557. Different carriers, such as gellan gum, sodium alginate, celite beads and silica, were tested as immobilization carriers, along with the role of the carrier concentration, biomass weight, number of spore-inoculated beads, and repeated utilization of the immobilized fungus. The maximum CyA production was 274 mg/l when using gellan gum (1 % w/v) and a mycelial weight of 7.5 % w/v supported the maximum production of CyA. Additionally, a combination of L-valine (6 g/l) and L-leucine (5 g/l) after 48 h of fermentation produced 1,338 mg/l when using gellan gum. The immobilized mycelia beads were found to remain stable for four repetitive cycles, indicating their use for semi-continuous CyA production.

Depletion of energy sources has drawn attention towards production of bio-butanol by fermentation. However, the process is constrained by product inhibition which results in low product yield. Hence, a new strategy wherein butanol was produced from butyraldehyde using alcohol dehydrogenase and NADH as a cofactor was developed. Butyraldehyde can be synthesized chemically or through fermentation. The problem of cofactor regeneration during the reaction for butanol production was solved using substrate coupled and enzyme coupled reactions. The conventional reaction produced 35% of butanol without regeneration of cofactor using 300 μM NADH. The process of substrate coupled reaction was optimized to get maximum conversion. NADH (30 μM) and 100 μg per ml of alcohol dehydrogenase (320 U mg−1) could convert 17.39 mM of butyraldehyde to butanol using ethanol (ratio of butyraldehye to ethanol 1 : 4) giving a maximum conversion of 75%. The enzyme coupled reaction under the same conditions showed only 24% conversion of butyraldehyde to butanol using the glutamate dehydrogenase-L-glutamate enzyme system for the regeneration of cofactor. Hence, substrate coupled reaction is suggested as a better method over the enzyme coupled reaction for the cost effective production of butanol.