Paracoccus sp. Strain LL1 as a Single Cell Factory for the Conversion of Waste Cooking Oil to Polyhydroxyalkanoates and Carotenoids

Background and objective: Polyhydroxyalkanoates have drawn significant attention as alternative to petroleum-based plastics; however, their industrial production is still hindered by the costly feed materials. Co-generation of other high-value products in addition to polyhydroxyalkanoate by the same microbial strains can be helpful in alleviating overall production cost up to 50%. This study for the first time demonstrates that polyhydroxyalkanoate and astaxanthin-rich carotenoids can be co-produced by Paracoccus sp. LL1 using waste cooking oil as substrate.Material and methods: The halophilic strain of Paracoccus sp. LL1 was grown under batch fermentation using mineral media supplemented with 1% (v v-1) waste cooking oil. Different surfactants were used to improve substrate utilization. Polyhydroxyalkanoate obtained after the fermentation was characterized by fluorescent microscopy, gas chromatography, and Fourier Transform Infra-Red spectroscopy.Results and conclusion: Oil as a substrate, led to 1.0 g l-1 poly (3-hydroxybutyrate-co-3-hydroxyvalerate) with concomitant production of 0.89 mg l-1 of carotenoids after 96 h. An enhancement of 2.7-folds in total cell dry mass was achieved when 0.1% (v v-1) Tween-80 was used as surfactant for ease in oil metabolism. Paracoccus sp. LL1 has the potential to serve as a single cell factory for bioconversion of cheap substrates into high value products.Conflict of interest: The authors declare no conflict of interest

Managing a Fleet of Autonomous Mobile Robots (AMR) using Cloud Robotics Platform

In this paper, we provide details of implementing a system for managing a fleet of autonomous mobile robots (AMR) operating in a factory or a warehouse premise. While the robots are themselves autonomous in its motion and obstacle avoidance capability, the target destination for each robot is provided by a global planner. The global planner and the ground vehicles (robots) constitute a multi agent system (MAS) which communicate with each other over a wireless network. Three different approaches are explored for implementation. The first two approaches make use of the distributed computing based Networked Robotics architecture and communication framework of Robot Operating System (ROS) itself while the third approach uses Rapyuta Cloud Robotics framework for this implementation. The comparative performance of these approaches are analyzed through simulation as well as real world experiment with actual robots. These analyses provide an in-depth understanding of the inner working of the Cloud Robotics Platform in contrast to the usual ROS framework. The insight gained through this exercise will be valuable for students as well as practicing engineers interested in implementing similar systems else where. In the process, we also identify few critical limitations of the current Rapyuta platform and provide suggestions to overcome them.Comment: 14 pages, 15 figures, journal pape

Identification, Activity and Disulfide Connectivity of C-di-GMP Regulating Proteins in Mycobacterium tuberculosis

C-di-GMP, a bacterial second messenger plays a key role in survival and adaptation of bacteria under different environmental conditions. The level of c-di-GMP is regulated by two opposing activities, namely diguanylate cyclase (DGC) and phosphodiesterase (PDE-A) exhibited by GGDEF and EAL domain, respectively in the same protein. Previously, we reported a bifunctional GGDEF–EAL domain protein, MSDGC-1 from Mycobacterium smegmatis showing both these activities (Kumar and Chatterji, 2008). In this current report, we have identified and characterized the homologous protein from Mycobacterium tuberculosis (Rv 1354c) named as MtbDGC. MtbDGC is also a bifunctional protein, which can synthesize and degrade c-di-GMP in vitro. Further we expressed Mtbdgc in M. smegmatis and it was able to complement the MSDGC-1 knock out strain by restoring the long term survival of M. smegmatis. Another protein Rv 1357c, named as MtbPDE, is an EAL domain protein and degrades c-di-GMP to pGpG in vitro. Rv1354c and 1357c have seven cysteine amino acids in their sequence, distributed along the full length of the protein. Disulfide bonds play an important role in stabilizing protein structure and regulating protein function. By proteolytic digestion and mass spectrometric analysis of MtbDGC, connectivity between cysteine pairs Cys94-Cys584, Cys2-Cys479 and Cys429-Cys614 was determined, whereas the third cysteine (Cys406) from N terminal was found to be free in MtbDGC protein, which was further confirmed by alkylation with iodoacetamide labeling. Bioinformatics modeling investigations also supported the pattern of disulfide connectivity obtained by Mass spectrometric analysis. Cys406 was mutated to serine by site directed mutagenesis and the mutant MtbC406S was not found to be active and was not able to synthesize or degrade c-di-GMP. The disulfide connectivity established here would help further in understanding the structure – function relationship in MtbDGC

Highly sensitive bovine serum albumin biosensor based on liquid crystal

A highly sensitive liquid crystal (LC) based bovine serum albumin (BSA) protein biosensor is designed. A uniform homeotropic alignment of nematic LC was observed in BSA free substrate which changed into homogeneous in presence of BSA. The change in the LC orientation is found to depend strongly on BSA concentration. This change in the LC alignment is attributed to the modification in the surface conditions which is verified by contact angle measurements. We have detected an ultra low concentration (0.5 mu g/ml) of BSA. The present study demonstrates the utilization of LC in the realization of high sensitivity biosensors