Bovine lactoferrin (bLf) has been well characterized as a multifunctional glycoprotein belonging to the transferrin family with antibacterial, antioxidant, anti-tumor, and antiviral activities. The main aim of this study was to determine the feeding strategies in fed-batch fermentation to obtain high-cell density in Pichia pastoris KM71H-3 for production of bLf. During the growth phase, two feeding strategies were performed: (i) Feeding glycerol solution; and (ii) feeding glycerol and nitrogen source solution with a carbon-to-nitrogen ratio of 3:1. In addition, two feeding induction strategies were applied: One-time feeding and continuous feeding with 0.5% of methanol every 24 h. The results showed that the highest cell density at OD 600 was 362.67 ± 2.04 when the feeding phase used a mix-feed solution of glycerol and nitrogen sources with a carbon to nitrogen ratio of 3:1 in the 2-L scale. Up-scaled production of lactoferrin from this strain was successfully employed in the 10-L and 100-L bioreactor with the highest OD 600 reaching 338.20 ± 3.38 and 375.50 ± 2.98, respectively. For optimal lactoferrin expression, methanol was fed continuously, corresponding to an induced methanol concentration of 0.5% per 24 h. The appropriate induction time was 48 h. This research provides information on cell growth and fed-batch strategies for enhanced bLf production using P. pastoris as a host, which may be applicable to the expression of other proteins from P. pastoris strains.

At the end of 2019, a novel coronavirus (CoV) appeared in Wuhan, China and has since spread to several countries and regions throughout the world. The disease caused by the novel CoV has been officially named CoV disease 2019 . This study provides additional data for the presence of anti-SARS-CoV-2 IgM and IgG antibodies in COVID-19 patients in Vietnam. The study also presents the development of a lateral flow immunoassay (LFA) strip for rapid simultaneous detection of the IgA/IgM/IgG antibodies against the SARS-CoV-2 virus in COVID-19 patients. The properties of the LFA test strip were evaluated by testing specimens from COVID-19 positive and negative patients confirmed by real-time PCR. Reproducibility and repeatability reached 100%. The LFA test strip did not show any cross-reactivity with 13 different pathogens and did not interfere with anticoagulants. The sensitivity and specificity of the LFA test strips were evaluated with 633 clinical samples and were found to be 91.06% and 98.74%, respectively. The Kappa statistics showed almost perfect agreement and correlation between our test strip and real-time PCR results (k coefficient = 0.902). From the obtained results, it could be suggested that the LFA test strip is a useful tool for rapid detection of antibodies against SARS-CoV-2 to accelerate epidemiological surveillance, to determine the situation of exposure to SARS-CoV-2, and to increase the diagnostic accuracy of the real-time PCR method for COVID-19.

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Abstract:In the present article, we report the biosensor can detect superparamagnetic nanoparticles (less than 10 nm in size) at various and low particle concentrations, which is of the importance role in biosensing applications.