Antony van Leeuwenhoek's entire output is contained in the hundreds of letters that he wrote from 1673 to 1723. This article discusses the content, features, and circumstances of the letters and their contemporary publishing history, especially in the Royal Society's Philosophical Transactions, as well as a brief history of the project begun in 1932 to publish a complete edition of Leeuwenhoek's letters in Dutch and English translation with linguistic, scientific, and historical annotations.

As a native CoQ10 producer, Rhodobacter sphaeroides has been extensively engineered to enhance CoQ10 production. However, the genetic manipulations using plasmids suffer from risk of plasmid loss during propagation process, biomass impairment due to cellular burden and bio-safety concerns. In this paper, genomic manipulations via Tn7 transposition was conducted to boost the CoQ10 biosynthesis in R. sphaeroides. The titer production and content of CoQ10 were improved by 18.44% and 18.87%, respectively compared to the wild type, when an additional copy of dxs and dxr were integrated into the genome. Further overexpression of idi and ispD by genomic integration created strain RSPCDDII with CoQ10 production and content of 81.23 mg/L and 5.93 mg/g, which were 54.28 and 55.97% higher than those of the wild type. The gene segments were successfully inserted into the attTn7 site of the R. sphaeroides genome. Meanwhile, the biomass was not affected. Compared to overexpression of genes on plasmids, this strategy could enhance protein expression to a proper level without affecting cell growth, and in a more stable manner.

Catecholamine stress hormones (norepinephrine, epinephrine, and dopamine) are signals that have been shown to be used as environmental cues, which affect the growth and virulence of normal microbiota as well as pathogenic bacteria. It has been reported that Escherichia coli and Salmonella use the two-component system proteins QseC and QseE to recognise catecholamines and so act as bacterial adrenergic receptors. In this study, we mutated the E. coli O157:H7 and Salmonella enterica serovar Typhimurium genes encoding QseC and QseE and found that this did not block stress hormone responsiveness in either species. Motility, biofilm formation, and analysis of virulence of the mutants using two infection models were similar to the wild-type strains. The main differences in phenotypes of the qseC and qseE mutants were responses to changes in temperature and growth in different media particularly with respect to salt, carbon, and nitrogen salt sources. In this physiological respect, it was also found that the phenotypes of the qseC and qseE mutants differed between E. coli and Salmonella. These findings collectively suggest that QseC and QseE are not essential for E. coli and Salmonella to respond to stress hormones and that the proteins may be playing a role in regulating metabolism.

We evaluated the antibiotic minimum inhibitory concentrations (MICs) of 123 Bacillus velezensis strains predominantly isolated from fermented soybean foods from Korea. When the 2018 European Food Safety Authority breakpoint values for Bacillus spp. were applied, all the strains were sensitive to chloramphenicol, clindamycin, erythromycin, gentamicin, kanamycin, tetracycline and vancomycin, and eight strains (6.5%) were resistant to streptomycin. The population distribution in MIC tests with streptomycin was continuous and the profile was clearly different from that expected for acquired antibiotic resistance. As of 25 October 2021, there were 181 complete published genomes of B. velezensis strains; 175 (96.7%) and 136 (75.2%) of these strains, respectively, possess potential tetracycline and streptomycin resistance genes tetL and ant(6) in the chromosome. In Bacillus licheniformis, SpeG confers resistance to clindamycin and there is an 'speG' gene annotated in the genomes of 180 B. velezensis strains; however, the gene products exhibit ≤26.6% amino acid identity with that from B. licheniformis DSM 13T. All the potential antibiotic resistance genes in the 181 B. velezensis strains were intrinsic, and traits of lateral gene transfer were not found. In this context, B. velezensis may not present a high risk in terms of antibiotic resistance in food fermentation or human use.

Escherichia fergusonii, an opportunistic zoonotic pathogen, has a greatly increased importance in public health with the discovery of cephalosporin- and colistin-resistant strains. The IncHI2 plasmid carrying mcr-1 has been reported in E. fergusonii, but the other types of plasmids carrying mcr-1 have never been reported. In this study, 268 samples of cecal contents or anal swabs were collected from slaughterhouses and farms in two cities in Zhejiang, China, where 54 E. fergusonii strains (18.88%) were isolated between 2020 and 2021. To our knowledge, this is the first report of the isolation of E. fergusonii in meat ducks (slaughterhouse). The minimum inhibitory concentration (MIC) of isolates was determined by the broth microdilution method, in which it was determined that the tetracycline resistance rate was the highest (83.33%) and the multidrug-resistance (MDR) rate was 75.93%. A total of four strains of colistin-resistant E. fergusonii were found and identified as mcr-1-positive by PCR. Importantly, these strains could transfer the mcr-1 gene to strain E. coli J53 by conjugation. Genome sequencing revealed that the mcr-1 genes of the above four strains were all located on the Incl2 plasmid, and the mobile element ISApl1 upstream of mcr-1 was missing. Moreover, the plasmid pEF45-4 (61 140 bp) harboring mcr-1 in strain EF20JDJ4045 was revealed by Oxford Nanopore Technology, showing high homology with the previously reported in E. coli. Taken together, the high antimicrobial resistance (AMR) rate of E. fergusonii may herald a novel reservoir of AMR genes and IncI2 plasmid may be an important factor affecting mcr-1 transfer in poultry.

Nitric oxide (NO) homeostasis plays a versatile role in pathogen-host interactions. To maintain NO homeostasis in favor of pathogens, microbes have evolved NO degradation systems besides NO synthesis pathway, in which the flavohemoglobin and S-nitrosoglutathione (GSNO) reductase are two key enzymes. We previously proved that MoSFA1, a GSNO reductase, is required for the growth and pathogenicity in Magnaporthe oryzae. In the present work, MoFHB1, a flavohemoglobin-encoding gene in M. oryzae was functionally characterized. Although the expression of the MoFHB1 gene was developmentally regulated during conidial germination and appressorium development, disruption of MoFHB1 did not change vegetative growth, conidiation and virulence. However, compared with the Δmosfa1 mutant, the Δmofhb1 mutant was significantly more sensitive to NO stress, and the expression of MoSFA1 gene in the Δmofhb1 mutant was significantly upregulated. Double deletion of MoSFA1 and MoFHB1 led to greater sensitivity of the fungus to NO stress than either of the single gene mutant, but no further reduction in pathogenicity was found compared with that of Δmosfa1 mutant. Taken together, MoFHB1 played an important role in NO detoxification but was dispensable for virulence of M. oryzae.