Continuous production of oxytetracycline in fluidized bed bioreactor by immobilized cells of Streptomyces varsoviensis MTCC-1537: effect of dilution and glucose loading rates.

Oxytetracycline (OT) production using glutaraldehyde cross-linked calcium alginate immobilized cells of Streptomyces varsoviensis in continuous fluidized bed reactor (FBR) was investigated. Initially, batch experiments were carried in stirred tank reactor (STR) and FBR using calcium alginate immobilized cells. Higher OT production of 0.45 gm/L was achieved by FBR when compared with 0.33 g/L of OT in STR. All subsequent studies were carried out in continuous mode of operation in FBR. During 21 days of operation, effect of glucose concentration and different dilution rates were studied. A maximum of 0.75 g/L OT was achieved in the medium having 10 g/L of glucose concentration. The highest OT concentration of 0.92 g/L and the highest yield of OT with respect to biomass at 0.1713 g/g were obtained at the dilution rate of 0.25 day(-1).

Lactic acid production by Lactobacillus delbrueckii in a dual reactor system using packed bed biofilm reactor.

AIMS: An integrated dual reactor system for continuous production of lactic acid by Lactobacillus delbrueckii using biofilms developed on reticulated polyurethane foam (PUF) is demonstrated. METHODS AND RESULTS: Lactobacillus delbrueckii was immobilized on PUF, packed in a bioreactor and used in lactic acid fermentation. The rate of lactic acid production was significantly high with a volumetric productivity of 5 g l(-1) h(-1) over extended period of time. When coupled to a bioreactor, the system could be operated as dual reactor for over 1000 h continuously without augmentation of inoculum and no compromise on productivity. CONCLUSIONS: Polyurethane foams offer an excellent support for biofilm formation. SIGNIFICANCE AND IMPACT OF THE STUDY: The system was very robust and could be operated for prolonged period at a volumetric productivity of 4-6 g l(-1) h(-1).

Enhanced production of antimicrobial sesquiterpenes and lipoxygenase metabolites in elicitor-treated hairy root cultures of Solanum tuberosum.

Potato (Solanum tuberosum) hairy root cultures, established by infecting potato tuber discs with Agrobacterium rhizogenes, were used as a model system for the production of antimicrobial sesquiterpenes and lipoxygenase (LOX) metabolites. Of the four sesquiterpene phytoalexins (rishitin, lubimin, phytuberin and phytuberol) detected in elicitor-treated hairy root cultures, rishitin (213 micrograms g-1 dry wt) was the most predominant followed by lubimin (171 micrograms g-1 dry wt). The elicitors also induced LOX activity (25-fold increase) and LOX metabolites, mainly 9-hydroxyoctadecadienoic acid and 9-hydroxyoctadecatrienoic acid, in potato hairy root cultures. The combination of fungal elicitor plus cyclodextrin was the most effective elicitor treatment, followed by methyl jasmonate plus cyclodextrin in inducing sesquiterpenes and LOX metabolites.

Antimicrobial activity of Ixora coccinea leaves.

Ether and methanol extracts of Ixora coccinea dry leaves were tested for their antimicrobial activity. Ether fraction was found to be more active than the methanol fraction.

Microbial degradation of pyridine using Pseudomonas sp. and isolation of plasmid responsible for degradation.

Pseudomonas (PI2) capable of degrading pyridine was isolated from the mixed population of the activated sludge unit which was being used for treating complex effluents, the strain was characterized. Aerobic degradation of pyridine was studied with the isolated strain and the growth parameters were evaluated. Pyridine degradation was further conformed by chromatography (HPLC) analysis. The process parameters like biomass growth and dissolved oxygen consumption were monitored during pyridine degradation. In order to conform with the plasmid capability to degrade pyridine, the requisite plasmid was isolated and transferred to DH 5alpha Escherichia coli. The subsequent biodegradation studies revealed the ability of the transformed plasmid capability to degrade the pyridine.

Enhanced production of plumbagin in immobilized cells of Plumbago rosea by elicitation and in situ adsorption.

Cell cultures of Plumbago rosea were immobilized in calcium alginate and cultured in Murashige and Skoog's basal medium containing 10 mM CaCl(2) for the production of plumbagin, an important medicinal compound. Studies were carried to find out the impact of immobilization on the increased accumulation of this secondary metabolite. Immobilization in calcium alginate enhanced the production of plumbagin by three, two and one folds compared to that of control, un-crosslinked alginate and CaCl(2) treated cells respectively. Cell loading at a level of 20% to the polymer volume (Na-alginate) was optimal and maximum plumbagin was obtained. At higher cell loading (40-50%), lower plumbagin accumulation was noticed. Addition of 200 mg l(-1) chitosan as an elicitor to the immobilized cells resulted in eight and two folds higher accumulation of plumbagin over control and immobilized cells. Also, more than 70% of the plumbagin was released into the medium, which is highly desirable for easy recovery of the product. Sucrose utilization rate of the cells was higher when cells were subjected to in situ product removal using Amberlite XAD-7. This may indicate that the toxicity of plumbagin was reduced on cells when it was removed from the medium. Cells subjected to combined treatments of chitosan, immobilization and in situ extraction showed a synergistic effect and yielded 92.13 mg g(-1) DCW of plumbagin which is 21, 5.7, 2.5 times higher than control, immobilized, immobilized and elicited cells respectively.

Biotreatability studies of pharmaceutical wastewater using an anaerobic suspended film contact reactor.

The pharmaceutical industrial effluents, which include several organic solvents and other toxic chemicals, are generally treated by aerobic process, which is cost intensive in nature. The alternative anaerobic route to degrade the toxic effluents is attractive due to the lower cost of treatment and the generation of gas, which can supplement the energy requirements. There are few reports on the anaerobic treatment of the pharmaceutical effluents. In the present investigation, the effluents from a bulk drug industry, which utilizes several organic chemicals, have been taken to assess their applicability for anaerobic treatment. The organic loading rates were varied from 0.25 kg/m3/day to 2.5 kg/m3/day and the COD reduction was found to be in the range of 60 to 80%. Long term operation of an anaerobic suspended film contact reactor carried out with 1.25 kg/m3/day was found to be optimum. The biogas generated during the degradation process was monitored and the methane content was found to be 60-70%.

The influence of inert solids on ethanol production by Saccharomyces cerevisiae.

The catalytic role of various inert solid supports on acceleration of alcohol fermentation by Saccharomyces cerevisiae was investigated. The enhanced rate of alcohol production was dependent on the nature of the support as well as on the amount used. Among all the tested supports, chitosan flakes showed the maximum yield of alcohol (93% of theoretical yield). This higher rate of alcohol production was associated with the twofold increase in the activity of alcohol dehydrogenase over control. Our results suggest that the addition of a small fraction of solids in submerged fermentations to facilitate cell anchorage for enhanced metabolic activity is easier and more economical compared to cell immobilization processes.

Synthesis of cyclodextrin glucosyl transferase by Bacillus cereus for the production of cyclodextrins.

A potent indigenous bacillus isolate identified as Bacillus cereus (RJ-30) was found to produce Cyclodextrin Glucosyl Transferase (CGTase) extracellularly. Process optimization of various fermentation parameters has been established for optimal growth of bacillus and the maximum enzyme synthesis. The organism had the highest specific growth rate (0.7 mu) with a generation time of 1 h in glucose containing medium at the conditions of pH 7.0, 37 degrees C at 300 rpm, 1.5 vvm of agitation, and aeration. At these conditions, it exhibited the maximum activity of 54 U/mL at the synthesis rate of 2.7 U/L/h. CGTase was produced from the early exponential growth and peaked during the midsporulating stage of about 16 h thereafter maintained at the same level of 50 U/mL. Saccharides containing media were better inducers than starch, and the influence of carbohydrate substrates has shown that enzyme synthesis is promoted by xylose (65 U/mL) and, more remarkably, by the supplementation of wheat bran extract in glucose medium (106 U/mL). This organism produced CGTase stably in a chemostat culturing over a period of 400 h with a maximum productivity of 5.4 kU/L/h (threefold higher than obtained in batch culturing [1.75 kU/L/h]). Comparatively, CGTase was produced by immobilized cells in a continuous fluidized bed reactor for over approx 360 h, at a relatively high dilution rate of 0.88 h-1 resulting in the productivity of 23.0 kU/L/h.