An Aerobic Anoxygenic Phototrophic Bacterium Fixes CO2 via the Calvin-Benson-Bassham Cycle

Aerobic anoxygenic phototrophic bacteria (AAnPB) are photoheterotrophs, which use light as auxiliary energy and require organic carbon (OC) for growth. Herein, we report the unusual strain B3, which is a true AAnPB because it requires oxygen for growth, harbours genes for cbb3- and bd-type cytochromes and acsF, and produces bacteriochlorophyll. The B3 genome encodes the complete metabolic pathways for AAnPB light utilization, CO2 fixation via Calvin-Benson-Bassham (CBB) cycle and oxidation of sulfite and H2, and the transcriptome indicated that all components of these pathways were fully transcribed. Expression of the marker genes related to photosynthesis, including pufM for light harnessing and rbcL for CO2 fixation, and the activity of RubisCO, the key enzyme in the Calvin-Benson-Bassham (CBB) cycle, increased in response to decreased OC supply. Large amounts of cell biomass were obtained in liquid BG11 medium under illumination. The strain thus likely photoautotrophically grows using sulfite or H2 as an electron donor. Similar GC contents between photosynthesis, the CBB cycle and 16S rRNA genes and the consistency of their phylogenetic topologies implied that light harnessing and carbon fixation genes evolved vertically from an anaerobic phototrophic ancestor of Rhodospirillaceae in Alphaproteobacteria. In conclusion, strain B3 represents a novel AAnPB characterized by photoautotrophy using the CBB cycle. This kind of AAnPB may be ecologically significant in the global carbon cycle.

Draft Genome Sequence of Enterococcus faecalis AS003, a Strain Possessing All Three Type II-a CRISPR Loci

ABSTRACT Enterococcus faecalis is a clinically significant member of the human microbiome. Three CRISPR-Cas loci are located in conserved locations. Previous studies provide evidence that E. faecalis strains with functional CRISPR-Cas genes are negatively correlated with antibiotic resistance. Here, we report the genome sequence of an unusual strain possessing all three CRISPR-Cas loci.

An invasive group A streptococcal infection outbreak: a community nursing experience

Invasive group A streptococcus (iGAS) can cause serious infections. Between January and July 2018, seven patients, living in the same geographical area and receiving district nursing care for wound management, were identified with iGAS. Further microbiological analysis of the cases identified the iGAS cases were the same type, emm 94. This was an unusual strain and suggested there was likely transmission via staff and contaminated equipment. Outbreak measures were implemented, including staff screening followed by commencement of chemoprophylaxis without waiting for results. No staff were identified as positive and no further cases identified. This outbreak report discusses the implementation of mass staff screening and the prompt commencement of chemoprophylaxis. This approach enabled staff to continue providing services and was an effective approach to managing outbreaks of this nature in a community setting. However, effective implementation requires early engagement from stakeholders to ensure clear communication and rationale is provided for staff.

Barista’s fracture: a new occupational hazard

Lesson Stress fracture of the clavicle is a rare injury usually occurring in high-level athletes. It is typically a result of repetitive sporting activity or unusual strain. We present the first case of an occupational clavicle stress fracture in a young female barista. The patient initially presented with insidious onset clavicular pain. There was no history of trauma, and an undisplaced fracture was present on the plain radiograph but overlooked by the emergency physicians. Two weeks later, the patient presented again with worsening symptoms, and a displaced fracture of the clavicle was diagnosed on plain radiograph. A thorough occupational history revealed the cause of her pain, which was the mechanical activity of coffee tamping and the fracture went on to unite with no further complications. No other cause was found on investigations including magnetic resonance imaging. The fracture healed with cessation of coffee tamping. This case highlights a previously unrecognised occupational hazard of coffee tamping as a potential cause of stress fracture of clavicle.

A family of all sp2-bonded carbon allotropes of topological semimetals with strain-robust nodal-lines

A family of all sp2-bonded, superelastic carbon allotropes of topological semimetals are predicted, exhibiting unusual strain-robust nodal-lines.

Tuning friction to a superlubric state via in-plane straining

Controlling, and in many cases minimizing, friction is a goal that has long been pursued in history. From the classic Amontons–Coulomb law to the recent nanoscale experiments, the steady-state friction is found to be an inherent property of a sliding interface, which typically cannot be altered on demand. In this work, we show that the friction on a graphene sheet can be tuned reversibly by simple mechanical straining. In particular, by applying a tensile strain (up to 0.60%), we are able to achieve a superlubric state (coefficient of friction nearly 0.001) on a suspended graphene. Our atomistic simulations together with atomically resolved friction images reveal that the in-plane strain effectively modulates the flexibility of graphene. Consequently, the local pinning capability of the contact interface is changed, resulting in the unusual strain-dependent frictional behavior. This work demonstrates that the deformability of atomic-scale structures can provide an additional channel of regulating the friction of contact interfaces involving configurationally flexible materials.