Development of an (S)-Equol-Producing Recombinant Strain with an Engineered Dihydrodaidzein Reductase
(S)-Equol, a well-known potential phytoestrogen, is a metabolite derived by certain human gut microorganisms. Its use and industrial production have been developed by exploiting naturally equol-forming bacteria, but its production has been limited by low productivity and the requirement of anoxic culture conditions. Lee et al. (p. 1992–2002) developed a recombinant (S)-equol-producing Escherichia coli strain whose (S)-equol yield from daidzein and productivity were increased under oxic conditions by introducing a dihydrodaidzein reductase P212A mutant. This work suggests that the developed strain, with its mutant dihydrodaidzein reductase and enhanced enantioselectivity, could be used for effective production of (S)-equol.
Bioaccumulation Patterns and Thermal Stabilities of Enteric Viruses in Live Oysters
The consumption of uncooked contaminated bivalve shellfish continues to pose a public health risk. These bivalve filter feeders can efficiently accumulate enteric pathogens within shellfish tissues. Araud et al. (p. 2086–2099) found that major enteric foodborne viruses exhibited different bioaccumulation patterns in oysters cultivated under natural conditions. The thermal stabilities of these viruses can be ranked from the most heat stable to the least stable as follows: hepatitis A virus > human rotavirus > Tulane virus > murine norovirus. By optimizing thermal processing parameters, all major enteric foodborne viruses can be efficiently inactivated in oyster tissues. These findings are critical for developing effective measures to limit shellfish-associated virus outbreaks.
A Novel Oral Streptococcus with Properties That Can Promote Dental Health
The definitive identification of beneficial bacteria in the human oral cavity has proven challenging but could facilitate the development of cost-effective strategies to control ubiquitous oral infectious diseases. Huang et al. (p. 2187–2201) characterized a potentially new oral Streptococcus species (A12) with an exceptionally high capacity to prevent acidification of oral biofilms. Further, A12 strongly inhibits the growth of the dental caries pathogen Streptococcus mutans and blocks intercellular communication systems that control the production of bacteriocins by this pathogen. Detailed characterization of similar oral isolates could support the rational design of probiotics that prevent oral infectious diseases.
Microfluidic Droplet Streaking for Single-Cell Cultivation and Bacterial Diversity Recovery
Enormous efforts have been made to unravel the unexplored diversity of microbial species, which represents the last truly untapped frontier in the diversity of life on Earth. Jiang and colleagues (p. 2210–2218) introduced a simple microfluidic streak plate (MSP) work flow involving the direct streaking of thousands of droplets on petri dishes for cultivation of single cells from complex microbial communities. The authors demonstrated that the MSP methodology is effective in obtaining abundant species as well as in the recovery of rare microbes. This newly developed method may increase the rate of isolation of uncultured and rare species for elucidation of their roles in the environment.
Using Magnetotactic Bacteria To Kill Staphylococcus aureus via Magnetic Hyperthermia
The systematic application of antibiotics has resulted in a worldwide emergence of both hospital-associated and community-associated methicillin-resistant Staphylococcus aureus strains. Chen et al. (p. 2219–2226) propose using magnetotactic bacteria to kill S. aureus via magnetic hyperthermia. Bacteria producing magnetic nanoparticles are attached to pathogenic S. aureus cells through high-affinity binding of S. aureus surface protein A to the Fc fragment of polyclonal antibodies coating the surface of magnetotactic bacteria. This work demonstrates that the application of an alternating magnetic field effectively kills S. aureus cells bound to the magnetic bacteria, both in vitro and in vivo, indicating a promising application in the fight against S. aureus skin or wound infections.
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- Development of an (S)-Equol-Producing Recombinant Strain with an Engineered Dihydrodaidzein Reductase
- Bioaccumulation Patterns and Thermal Stabilities of Enteric Viruses in Live Oysters
- A Novel Oral Streptococcus with Properties That Can Promote Dental Health
- Microfluidic Droplet Streaking for Single-Cell Cultivation and Bacterial Diversity Recovery
- Using Magnetotactic Bacteria To Kill Staphylococcus aureus via Magnetic Hyperthermia
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