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In this study, polyhydroxyalkanoates (PHA) accumulation by Halomonas venusta KT832796, a moderate halophilic bacteria isolated from marine source was studied. Both nutritional requirements and process parameters for submerged cultivation of the organism in bioreactor have been standardized. From the shake flask studies, glucose and ammonium citrate as carbon and nitrogen source produced maximum PHA at a ratio 20 with 3.52 g/L of dry cell weight and 70.56% of PHA content. However, ammonium sulfate as the nitrogen source was found to be more suitable for fed-batch cultivation. Several feeding strategies including pH-based fed-batch and variants of pulse feeding were studied to improve the PHA levels. pH-based feeding, although improved PHA level to 26 g/L, most of the carbon flux was diverted towards biomass formation; hence, the percent PHA was only 39.15% of the dry cell weight. Maximum PHA of 33.4 g/L, which corresponded to 88.12% of the dry cell, was obtained from high concentration single pulse method. There was a net 8.65-fold increase in PHA using this feeding strategy when compared to batch studies. According to our knowledge, this is the highest amount of PHA reported for a Halomonas venusta strain.

Fermentation of batter is an integral part of the preparation of jilebi, a traditional ready-to-eat sweet product of Indian sub-continent. The flowability and pourability of batter are crucial for forming jilebi strands during frying. Flowability and pourability have been determined from simulation studies based on the movement of batter on an inclined surface and the exit from an orifice, respectively; simple gadgets have been designed to determine these two characteristics along with providing the definitions. Response surface experimental design consisting of moisture content (50-65%), amount of added curd (0-10%) and time of fermentation (0-24 h) has been employed. The response functions are pH, flowability and pourability. Strong interaction effects of added curd and time of fermentation on the response functions have been observed. An increase in added curd and time of fermentation decreases pH in a curvilinear manner as both linear and quadratic effects are significant (p≤0.01). Moisture content has a non-significant effect on pH but markedly affects the flowability and pourability of batter. Flowability and pourability decreases when there is an increase in consistency index or apparent viscosity.

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