Production and recovery process of polyhydroxybutyrate (PHB) from waste activated sludge.

Polyhydroxybutyrate (PHB) is bacterial storage polyester, currently receiving much attention because of its biodegradable potential. Production of microbial polymers is expensive due to supplementary carbon source and downstream processing cost. The present study aimed at reducing the fermentation carbon source cost by using waste activated sludge and wastewater, and evaluating the use of proper solvent for the recovery of PHB from activated sludge to minimize the downstream cost. To improve the recovery process efficiency, different strategies for the extraction and recovery of the polymer from the waste activated sludge were applied. The maximum solubility of PHB (80%) was observed in chloroform, and precipitation with methanol (95%) was observed. Impurities interference in the PHB recovery process was also studied. By using these optimized recovery processes with optimized C:N ratio 10, the maximum product recovery was observed to be 62.3% (w/w). The results are presented and discussed in this paper.

Effect of exposure to domestic cooking fuels on bronchial asthma.

The effect of indoor air pollution due to domestic cooking with biomass fuel and liquefied petroleum gas (LPG) on the course of bronchial asthma was examined in one hundred non-smoking female asthmatics. The parameters for evaluation were symptoms, emergency visits, and drug requirements. The patients also measured peak expiratory flow rate (PEFR) at home five times daily over a period of one week and the levels of carboxyhaemoglobin (COHb) were estimated randomly during clinic visits. The COHb levels (%) were 4.1 +/- 0.9 and 3.5 +/- 0.6 in the two groups with 22-30% of the subjects reporting increased symptoms during cooking. The number of emergency admissions and the daily requirement of steroids were comparable in both the groups. The PEFR values were lower than the predicted values in both the groups at all times. Further, the readings after exposure to cooking fuels were lower than those before cooking in both the groups (p < 0.01) and these values were similar to those observed during early morning records at 6 AM, which were the lowest. It was concluded that exposure to biomass fuel and LPG affect pulmonary function (PEFR) in asthmatics and both types of fuels affect the airway function and symptoms of bronchial asthma in a similar manner.

Detection of HIV seropositivity during an outbreak of Japanese encephalitis in Manipur.

An epidemic outbreak of Japanese encephalitis (JE) occurred during mid 1995. Sixteen serum samples from patients with history of febrile headache, convulsions, mental confusion, neck rigidity etc. were sent to the Department of Virology, School of Tropical Medicine, Calcutta, in August, 1995. Twelve (75%) showed HIV antibody against JEV. Out of these 12 sera showing HIV antibody titre between 1:40 and 1:160, eight (66.6%) showed IgM antibody, giving the presumptive diagnosis of recent JEV infection. Five of these 16 sera showed HIV seropositivity (31.25%). Concomitant JEV and HIV infection could be detected in 3 cases. However, in 2 sera HIV titre were less than 1:20. This is probably the first documentation of concomitant JEV and HIV infection in the eastern India.

HCV activity in Calcutta--a serological study.

HCV infection, a global public health problem is quite prevalent in India. In the present study conducted during February-July 1996 a total of 153 samples of different age groups and of both sexes were tested by ELISA for detection of Anti-HCV antibody. Anti-HCV was found in 13% of multi-transfused cases and in 8.8% cases with multiple needle-stick injury. Maximum seropositivity (20%) could be observed amongst males between 31-40 yrs. age group. HCV activity was noted more in males (13%) than in females (8.2%) and more relatively in subjects without a history of jaundice (11.5%) than those having the features of jaundice (10.5%). An increasing trend has also been observed amongst the multi-transfused cases in Calcutta.

An in vitro qualitative assay for the detection of antibodies to HIV type 1/2 contained in human saliva.

There is ample evidence that saliva contains secretory antibody against most infections. Therefore, saliva has been recommended as a non invasive, safe and effective alternative to serum, for HIV antibody testing. The present study attempted comparative evaluation of antibody detection by serum and saliva specimens in laboratory by ELISA and Western Blot for diagnosis of HIV infection in the Indian situation. From a study of 42 test sera it is concluded that test apart from its simplicity and reproducibility, is almost free from any false positive and false negative reactions.

Plasmid-determined degradative metabolism and halophilism of Vibrio parahaemolyticus.

A set of 25 Kanagawa(+) and Kanagawa(-) strains of V. parahaemolyticus was studied for their ability to degrade hydrocarbons in minimal media. All strains gave positive results with respect to crystal violet (CV), methyl violet, liquid paraffin, benzene, naphthalene and phenol. The CV double ring (CVDR) response had earlier appeared to be a significant pathogenic marker [Chakrabarti et al, Indian J Med Res, 85 (1987) 508]. The CVDR response was found also to be a biodegradative marker, and correlates perfectly well with polymyxin resistance and low level of halophilism (4% NaCl). All these markers (characters) were found to be controlled by a single plasmid in the wild type. Elimination of the plasmid, as confirmed by gel electrophoresis studies, resulted in loss of CVDR response, polymyxin resistance, and acquisition of halophilism at a higher level (> 7%). The massive drainage of industrial effluents, rich in hydrocarbons, in the estuarine areas in many countries might have altered the ecosystem in favour of V. parahaemolyticus and its emergence as a new biodegradative and enterotoxigenic pathogen, contaminating fauna and flora in the littoral sea regions, with increased changes of communicability to humans.