Characterization of Riboflavin-Producing Strains of Lactobacillus plantarum as Potential Probiotic Candidate through in vitro Assessment and Principal Component Analysis.

Lactic acid bacteria (LAB) are known for their probiotic properties, but only a few strains produce riboflavin. We evaluated the probiotic properties of four riboflavin-producing strains of Lactobacillus plantarum (BBC33, BBC32A, BIF43, and BBC32B) by using in vitro assessment and carried out multivariate principal component analysis (PCA) to select the best strain. Safety, antioxidant, and exopolysaccharide-producing properties were also studied. Lact. plantarum BBC33 showed better probiotic potential, followed by strain BIF43. Lact. plantarum BBC32A degraded mucin and excluded as a potential probiotic candidate. Lact. plantarum BIF43, BBC33, and BBC32A tolerated simulated gastrointestinal conditions and their overnight cell-free culture supernatants (CFSs, pH 4.0-4.3) inhibited the growth of Escherichia coli AF10, Salmonella Typhi MTCC98, Bacillus cereus NCDC250, and Pseudomonas aeruginosa NCDC105. Lact. plantarum BIF43 and BBC33 did not degrade mucin, adhered to human epithelial colorectal adenocarcinoma Caco-2 cells (22-25%), and aggregated with indicators (30-50%). Moreover, both were non-hemolytic and sensitive to most antibiotics tested. Of the two selected strains, BIF43 showed better exopolysaccharides (EPS) producing phenotype. The CFSs of all strains showed high (85-93%) 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. PCA confirmed the results obtained from in vitro probiotic experiments and supported the selection of Lact. plantarum BIF33 and BBC43, as potential probiotics.

New insights into mammalian signaling pathways using microfluidic pulsatile inputs and mathematical modeling.

Temporally modulated input mimics physiology. This chemical communication strategy filters the biochemical noise through entrainment and phase-locking. Under laboratory conditions, it also expands the observability space for downstream responses. A combined approach involving microfluidic pulsatile stimulation and mathematical modeling has led to deciphering of hidden/unknown temporal motifs in several mammalian signaling pathways and has provided mechanistic insights, including how these motifs combine to form distinct band-pass filters and govern fate regulation under dynamic microenvironment. This approach can be utilized to understand signaling circuit architectures and to gain mechanistic insights for several other signaling systems. Potential applications include synthetic biology and biotechnology, in developing pharmaceutical interventions, and in developing lab-on-chip models.

Band-pass processing in a GPCR signaling pathway selects for NFAT transcription factor activation.

Many biological processes are rhythmic and proper timing is increasingly appreciated as being critical for development and maintenance of physiological functions. To understand how temporal modulation of an input signal influences downstream responses, we employ microfluidic pulsatile stimulation of a G-protein coupled receptor, the muscarinic M3 receptor, in single cells with simultaneous real-time imaging of both intracellular calcium and NFAT nuclear localization. Interestingly, we find that reduced stimulation with pulses of ligand can give more efficient transcription factor activation, if stimuli are timed appropriately. Our experiments and computational analyses show that M3 receptor-induced calcium oscillations form a low pass filter while calcium-induced NFAT translocation forms a high pass filter. The combination acts as a band-pass filter optimized for intermediate frequencies of stimulation. We demonstrate that receptor desensitization and NFAT translocation rates determine critical features of the band-pass filter and that the band-pass may be shifted for different receptors or NFAT dynamics. As an example, we show that the two NFAT isoforms (NFAT4 and NFAT1) have shifted band-pass windows for the same receptor. While we focus specifically on the M3 muscarinic receptor and NFAT translocation, band-pass processing is expected to be a general theme that applies to multiple signaling pathways.

Cavitation assisted synthesis of fatty acid methyl esters from sustainable feedstock in presence of heterogeneous catalyst using two step process.

The present work reports the intensification aspects for the synthesis of fatty acid methyl esters (FAME) from a non-edible high acid value Nagchampa oil (31 mg of KOH/g of oil) using two stage acid esterification (catalyzed by H2SO4) followed by transesterification in the presence of heterogeneous catalyst (CaO). Intensification aspects of both stages have been investigated using sonochemical reactors and the obtained degree of intensification has been established by comparison with the conventional approach based on mechanical agitation. It has been observed that reaction temperature for esterification reduced from 65 to 40 °C for the ultrasonic approach whereas there was a significant reduction in the optimum reaction time for transesterification from 4h for the conventional approach to 2.5h for the ultrasound assisted approach. Also the reaction temperature reduced marginally from 65 to 60 °C and yield increased from 76% to 79% for the ultrasound assisted approach. Energy requirement and activation energy for both esterification and transesterification was lower for the ultrasound based approach as compared to the conventional approach. The present work has clearly established the intensification obtained due to the use of ultrasound and also illustrated the two step approach for the synthesis of FAME from high acid value feedstock based on the use of heterogeneous catalyst for the transesterification step.