Paper-based electrochemical biosensor for diagnosing COVID-19: Detection of SARS-CoV-2 antibodies and antigen.

Genome sequencing of Streptomyces, myxobacteria, and fungi showed that although each strain contains genes that encode the enzymes to synthesize a plethora of potential secondary metabolites, only a fraction are expressed during fermentation. Interest has therefore grown in the activation of these cryptic pathways. We review current progress on this topic, describing concepts for activating silent genes, utilization of “natural” mutant-type RNA polymerases and rare earth elements, and the applicability of ribosome engineering to myxobacteria and fungi, the microbial groups known as excellent searching sources, as well as actinomycetes, for secondary metabolites.

/pdf/new-strategies-for-drug-discovery-activation-of-silent-or-x84hyxxii6.pdf

New strategies for drug discovery: activation of silent or weakly expressed microbial gene clusters

New strategies for drug discovery: Activation of silent or weakly expressed microbial gene clusters

Regulation of antibiotic production in Actinobacteria: new perspectives from the post-genomic era.

Lipopeptide surfactants: Production, recovery and pore forming capacity.

Coronavirus disease 2019 (COVID-19), which emerged in Wuhan, China in December 2019, is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and has become a major global public h...

https://www.tandfonline.com/doi/pdf/10.1080/22221751.2020.1773324

Patterns of IgG and IgM antibody response in COVID-19 patients.

Daptomycin, a cyclic lipopeptide antibiotic produced by Streptomyces roseosporus, displays potent activity against a variety of gram-positive pathogens. There is a demand for generating high-producing strains for industrial production of this valuable antibiotic. Ribosome engineering is a powerful strategy to enhance the yield of secondary metabolites. In this study, the effect of a diterpenoid antibiotic pleuromutilin resistance mutation on daptomycin production was assessed. Spontaneous pleuromutilin-resistant derivatives of S. roseosporus were isolated. Sequencing of rplC locus (encoding the ribosomal protein L3) showed a point mutation at nt 455, resulting in the substitution of glycine with valine. G152V mutants showed increased production of daptomycin by approximately 30% in comparison with the wild-type strain. Its effect on daptomycin production was due to enhanced gene transcription of the daptomycin biosynthetic genes. In conclusion, pleuromutilin could be used as a novel ribosome engineering agent to improve the production of desired secondary metabolites.

/pdf/improvement-of-daptomycin-production-in-streptomyces-3xtl6fh82b.pdf

Improvement of Daptomycin Production in Streptomyces roseosporus through the Acquisition of Pleuromutilin Resistance

Aims: Daptomycin, one of the A21978C factors produced by Streptomyces roseosporus, is an acidic cyclic lipopeptide antibiotic with potent activity against a variety of Gram-positive pathogens To increase the titre of this extensively used and clinically important antibiotic, we applied a reported-guided rpsL mutation selection system to generate strains producing high levels of A21978C



Methods and Results:  In the reporter design, dptE was chosen as the overexpressing target, and neo-encoding neomycin phosphotransferase as the reporter Using this reporter-guided selection system, 20% of the selected, streptomycin-resistant mutants produced greater amounts of A21978C than the starting strain The selection system increased the screening efficiency about 10-fold with a frequency of 1·7% A21978C overproducing strains among strr mutants A21978C production was increased approximately 2·2-fold in the rpsL K43N mutant



Conclusions:  The combination of ribosome engineering and reporter-guided mutant selection generated an A21978C overproducing strain that produced about twice as much A21978C as the parental strain



Significance and Impact of the Study:  The strategies presented here, which integrated the advantages of both ribosome engineering and reporter-guided mutation selection, could be applied to other bacteria to improve their yield of secondary metabolites

Improvement of A21978C production in Streptomyces roseosporus by reporter-guided rpsL mutation selection.

Aims
The wblA gene, encoding a homolog of the WhiB family protein, was identified in the sequenced genome of daptomycin producer S.roseosporus. To explore the function of wblA, we construct wblA disruption strains, complemented strains and overexpression strains to test whether it can affect the production of secondary metabolites and morphogenesis.

Methods and results
We constructed disruption strains by homologous recombination in S.roseosporus. The disruption mutant of wblA could block aerial mycelium sporulation and enhance the production of daptomycin by 51%. In contrast, overexpression of wblA resulted in significantly decreased the yield of daptomycin. In agreement with it, the transcription of key daptomycin regulatory genes atrA, dptR2 and dptR3 and structural gene dptE remarkably increased in the wblA disruption mutant.

Conclusions
wblA plays a key role in control of daptomycin biosynthesis and is essential for sporulation. The disruption of wblA could accumulate the transcription level of some key genes involving in daptomycin biosynthesis.

Significance and Impact of the Study
Daptomycin is an important antibiotic with potent activity against a variety of Gram-positive pathogens. This study demonstrates that valuable improvement in the yield of daptomycin can be achieved through modulating the expression of wblA transcription regulator.

This article is protected by copyright. All rights reserved.

https://sfamjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/jam.13512

wblA, a pleiotropic regulatory gene modulating morphogenesis and daptomycin production in Streptomyces roseosporus

Objective To study the regulation of laeA overexpression on mevastatin production and sporulation in Penicillium citrinum Methods We cloned the laeA gene from Penicillium citrinum and constructed the vector pGiHTGi-laeA The plasmid pGiHTGi-laeA was transformed in Penicillium citrinum by agrobacterium tumefaciens-mediated transformation Positive transformants were detected by cloning the hygromycin gene The mevastatin production of the wild type and OE:: laeA was compared by HPLC The conidia number was counted by blood counting chamber The biosynthetic gene cluster expression quantity of mevastatin in the wild type and OE: :laeA were analyzed by qRT-PCR Results We constructed the plasmid pGiHTGi-laeA, and screened the positive transformants that overexpress the laeA in Penicillium citrinum With the overexpression of laeA, the mevastatin production was increased from (069 ± 012) mg/g to (402 ± 050) mg/g dry cell weight Compared to the wild type strain, the laeA expression quantity in the OE :: laeA strain increased 29%, and the mlcB expression increased 72%, the mlcR expression increased 153% Moreover, the overexpression of laeA would decrease the conidia number Conclusion Overexpression of LaeA enhances mevastatin production and reduces sporulation of Penicillium citrinum, with increases expression of pathway-regulator mlcR, and biosynthetic gene MlcR These results could guide global regulatory mechanism of mevastatin biosynthesis and the exploitation of high-production strain

Changhua Hu

Papers

Patterns of IgG and IgM antibody response in COVID-19 patients.

Improvement of Daptomycin Production in Streptomyces roseosporus through the Acquisition of Pleuromutilin Resistance

Improvement of A21978C production in Streptomyces roseosporus by reporter-guided rpsL mutation selection.

wblA, a pleiotropic regulatory gene modulating morphogenesis and daptomycin production in Streptomyces roseosporus

Overexpression of LaeA enhances mevastatin production and reduces sporulation of Penicillium citrinum