Development of operating process for continuous production of biomass by Tetradesmus obliquus (MT188616.1) in a hollow fiber membrane photobioreactor.

An effective prototype of photobioreactor namely hollow fiber membrane bioreactor is employed to produce algal biomass for biofuel production. The effect of two-stage cultivation system on the biomass productivity and lipid production is studied using freshwater green microalga Tetradesmus obliquus MT188616.1. The hybrid system combines exponential biomass production in hollow fiber membrane photobioreactor (HFMPBr) and a coordinated high-lipid stimulation phase in nitrogen-deprived medium by the shake flask method. This work is proposed to examine the usefulness of HFMPBr module to enhance the microalgal growth rate through the effective mass transfer by standardizing the culture medium re-circulation flow rates (5 - 45 mL min-1) through the hollow fiber membranes. Cultivation is carried out at continuous mode in HFMPBr containing polysulfone fabricated membranes at fixed light intensity of 50 µmol m-2 s-1 and temperature at 28 °C. Biomass productivity and specific growth rate obtained are 0.44 g L-1d-1 and 1.61 µ d-1 with a lipid yield of 0.1 g L- 1. The key operating parameter i.e., liquid flow rate is optimized based on biomass production. The highest biomass concentration is produced at the flow rate of 45 mL min-1. The results showed that HFMPBr module is a better choice for the algal-cultivation to obtain higher biomass yield.

Soy whey based medium for optimized phytase activity in Saccharomyces cerevisiae MTCC 5421 and α-D-galactosidase and antibacterial activities in Lactobacillus plantarum MTCC 5422 by response surface methodology.

Soy whey based growth medium for yeast enabled the native isolate of Saccharomyces cerevisiae MTCC 5421 to produce 198 U/ml of phytase activity against that of 135 U/ml in potato dextrose broth. In the same medium for lactic acid bacteria, the isolate of Lactobacillus plantarum MTCC 5422 was able to elaborate α-D-galactosidase activity of 10.6 U/ml in comparison to 6 U/ml in Lactobacillus MRS broth. Using this formulated medium, a central composite experimental design based on 5 variables of 3 factors namely incubation temperature, pH level and incubation period showed that S. cerevisiae could produce 200 U/ml of phytase in 36 h at 30 °C and pH 3.5. Similarly, L. plantarum in 33 h at 37 °C and pH 6.6 exhibited 14.2 U/ml of α-D-galactosidase activity, whereas the antibacterial activity of 14.4 AU/ml against Bacillus cereus was evident in 42 h at 42 °C and pH 6.0. The phytase and antibacterial activity units visualized in response surface plots were more or less close to those obtained with the experimental design treatments.

Molecular characterization of native isolates of lactic acid bacteria, bifidobacteria and yeasts for beneficial attributes.

In a changing scenario of food habits being associated with wellness factors through the concepts of probiotics and prebiotics, an attempt has been made to characterize on molecular basis, the desirable benefits associated with natural isolates of lactic acid bacteria, bifidobacteria, and yeasts. From a diverse range of foods and related samples, based on conventional microbiological protocols, three well-characterized natural isolates of Lactobacillus plantarum MTCC 5422, Bifidobacterium adolescentis MTCC 5423 and Saccharomyces cerevisiae MTCC 5421 were selected. The cultures of L. plantarum and B. adolescentis showed positive polymerase chain reaction (PCR) amplification with oligonucleotide primers targeting genus-specific 16 S rRNA for Lactobacillus and fructose-6-phosphate phosphoketolase for Bifidobacterium. Similarly, species-specific positive amplification in PCR was observed with primers of phytase (acid phosphatase) in S. cerevisiae and alpha-D: -galactosidase and bile salt hydrolase in L. plantarum and B. adolescentis. The cultures of L. plantarum and B. adolescentis exhibited a broad spectrum antibacterial activity against selected foodborne pathogenic bacterial species and tolerance to acid and bile. Gene sequence of respective PCR-amplified products confirmed the genetic identity of the isolated cultures as L. plantarum and B. adolescentis showing 99% homology with the documented sequence of established gene bank.