Improving Production of Tacrolimus In Streptomyces Tacrolimicus (ATCC 55098) Through Development of Novel Mutant by Dual Mutagenesis

ABSTRACT Tacrolimus is a polyketide macrolide produced by Streptomyces species which is widely used as anti-fibrotic agent and potent immunosuppressant. In this article dual mutagenesis approach using mutagens (NTG+EMS+UV) was used to develop a mutant strain of Streptomyces tacrolimicus (ATCC 55098) for higher tacrolimus production and this strain showed higher tacrolimus production at 82.5 mg/l. Interestingly; addition of L-Lysine (0.2 g/l) into the production medium further enhanced the tacrolimus production to ~102 mg/l at 7-L fed-batch bioreactor. To the best of our knowledge this is the first report mentioning efficient strain development for higher production of tacrolimus using dual mutagenesis. The obtained data presents an impressive model for higher production of tacrolimus and enhanced our understanding regarding improvement in production capacity of tacrolimus in Streptomyces tacrolimicus.

Effect of smoking on atopic predisposition and sensitisation to allergens.

BACKGROUND: Previous studies elsewhere have shown higher serum immunoglobulin E (IgE) levels in smokers and an association between smoking and sensitisation to allergens. Such information is not available for Indian population. Hence, the present study was carried out to evaluate the effect of smoking on atopic predisposition and sensitisation to aeroallergens. METHODS: A total of 70 subjects were included in the present study comprising of 25 smokers, 22 reformed smokers and 23 non-smokers. Absolute eosinophil count (AEC), serum total IgE levels and skin prick test (SPT) against common aeroallergens were performed in all the subjects along with breath carbon monoxide (CO) levels and pulmonary function tests. RESULTS: Smokers showed significantly higher serum total IgE levels (328.80 +/- 161.82 IU/mL) as compared to reformed smokers 177.27 +/- 86.47 IU/mL) and non-smokers (29.56 +/- 9.75 IU/mL). A number of subjects among smokers and reformed smokers elicited positive SPT reactions to various allergen extracts. Non-smokers did not show any significant positive skin reaction. The AECs were slightly higher in smokers (350 +/- 1145.61/mm3) as compared to reformed smokers (305 +/- 146.33/ mm3). Breath CO was considerably higher (greater than three times) in smokers than reformed smokers. However, reformed smokers showed greater airways obstruction than smokers. The former also had higher Brinkman index (646.81 +/- 392.32) as compared to the latter (448.36 +/- 279.86). CONCLUSIONS: Smokers had significantly higher IgE serum levels than reformed smokers and non-smokers. Smoking seems to induce an atopic orientation and allergen sensitisation in individuals.

Relevance of serum IgE estimation in allergic bronchial asthma with special reference to food allergy.

Studies suggest the importance of serum total and specific IgE in clinical evaluation of allergic manifestations. Such studies are lacking in Indian subcontinent, though a large population suffer from bronchial asthma. Here relevance of serum total and specific IgE was investigated in asthmatics with food sensitization. A total of 216 consecutive patients (mean age 31.9 years, S.D. 11.8) were screened by various diagnostic testing. Out of 216 patients, 172 were with elevated serum total IgE (201 to > 800 IU/ml). Rice elicited marked positive skin prick test reactions (SPT) in 24 (11%) asthma patients followed by black gram 22 (10%), lentil 21 (9.7%) and citrus fruits 20 (9.2%). Serum total IgE and specific IgE showed significant correlation, p = 0.005 and p = 0.001, respectively, with positive skin tests. Blinded food challenges (DBPCFC) with rice and or black gram confirmed food sensitization in 28-37% of cases. In summary, serum total IgE of 265 IU/ml or more with marked positive SPT (4 mm or more) can serve as marker for atopy and food sensitization. Specific IgE, three times of normal controls correlates well with positive DBPCFC and offers evidence for the cases of food allergy.