Light-driven soft microrobots based on hydrogels and LCEs: development and prospects.

In the daily life of mankind, microrobots can respond to stimulations received and perform different functions, which can be used to complete repetitive or dangerous tasks. Magnetic driving works well in robots that are tens or hundreds of microns in size, but there are big challenges in driving microrobots that are just a few microns in size. Therefore, it is impossible to guarantee the precise drive of microrobots to perform tasks. Acoustic driven micro-nano robot can achieve non-invasive and on-demand movement, and the drive has good biological compatibility, but the drive mode has low resolution and requires expensive experimental equipment. Light-driven robots move by converting light energy into other forms of energy. Light is a renewable, powerful energy source that can be used to transmit energy. Due to the gradual maturity of beam modulation and optical microscope technology, the application of light-driven microrobots has gradually become widespread. Light as a kind of electromagnetic wave, we can change the energy of light by controlling the wavelength and intensity of light. Therefore, the light-driven robot has the advantages of programmable, wireless, high resolution and accurate spatio-temporal control. According to the types of robots, light-driven robots are subdivided into three categories, namely light-driven soft microrobots, photochemical microrobots and 3D printed hard polymer microrobots. In this paper, the driving materials, driving mechanisms and application scenarios of light-driven soft microrobots are reviewed, and their advantages and limitations are discussed. Finally, we prospected the field, pointed out the challenges faced by light-driven soft micro robots and proposed corresponding solutions.

Antimicrobial Resistance and Molecular Characterization of Escherichia coli from Healthy Chickens in Shandong, China from 2009 to 2014.

Antimicrobial resistance (AMR) is a great threat to animal and public health. Here, we conducted a surveillance of Escherichia coli isolated from healthy chickens during 2009-2014 to identify the characteristics of AMR. A total of 351 (95.64%) E. coli isolates were obtained from 367 healthy chicken fecal samples collected from 6 farms located in Shandong Province, China. The susceptibility to 10 antimicrobials, the prevalence of antibiotic resistance genes (ARGs), phylogenetic clustering, and multilocus sequence typing were evaluated. The isolates exhibited high resistant rates (>95%) to ampicillin, cefotaxime, ciprofloxacin, ceftiofur, and enrofloxacin. The most prevalent ARGs were blaCTX-M (36.36%), aac(6')-Ib-cr (30.79%), qnrS (29.62%), oqxAB (27%), mcr-1 (15.83%), blaTEM (9.09%), qnrC (3.52%), qnrD (0.88%), and qepA (0.29%). Phylogenetic clustering analysis indicated that the most prevalent group was group D (37.89%), followed by group B1 (34.76%), A (24.22%), and B2 (3.13%). Fifty-seven sequence types (STs) were identified among the 124 blaCTX-M-positive strains, and the dominant STs were ST354 (13.71%), ST117 (5.65%), ST155, ST2309, and ST2505 (4.84% each). There was a significant association between 17 pairs of AMR phenotypes, 14 pairs of ARGs, and 11 pairs of AMR-ARGs. The strongest association was found between ST602 and qnrC (odds ratios: 22.2). This study implied that E. coli isolated from healthy chickens could potentially serve as a reservoir of AMR and ARGs, and significant associations exist among AMR, ARGs, phylogenetic groups, and STs. Our study highlighted the need for routine surveillance of AMR in healthy chickens, and promoting appropriate antibiotic use and implementing regular monitoring of resistance in broilers are crucial for fostering the development of the poultry industry and safeguarding public health.

Toxin gene detection and antibiotic resistance of Clostridium perfringens from aquatic sources.

Clostridium perfringens is a zoonotic opportunistic pathogen that produces toxins that can cause necrotic enteritis and even "sudden death disease". This bacterium is widely distributed in the intestines of livestock and human, but there are few reports of distribution in aquatic animals (Hafeez et al., 2022). In order to explore the isolation rate of C. perfringens and the toxin genes they carry, 141 aquatic samples, including clams (Ruditapes philippinarum), oysters (Ostreidae), and mud snails (Bullacta exerata Philippi), were collected from the coastal areas of Shandong Province, China. C. perfringens strains were tested for cpa, cpb, etx, iap, cpb2, cpe, netB, and tpeL genes. 45 clam samples were boiled at 100 °C for 5 min before bacteria isolation. 80 strains were isolated from 141 samples with the positive rate being 57 %.And the positive rates of cooked clams was 87 % which was higher than the average. In detection of 8 toxin genes, all strains tested cpa positive, 3 strains netB positive, and 2 cpb and cpe, respectively. 64 strains were selected to analyze the antibiotic resistance phenotype of 10 antibiotics. The average antibiotic resistance rates of the strains to tetracycline, clindamycin, and ampicillin were 45 %, 20 %, and 16 % respectively, and the MIC of 4 strains to clindamycin was ≥128 µg/mL. A high isolation rate of C. perfringens from aquatic animals was shown, and it was isolated from boiled clams for the first time, in which cpe and netB toxin genes were detected for the first time too. The toxin encoded by cpe gene can cause food poisoning of human, thus the discoveries of this study have certain guiding significance for food safety. Antibiotics resistant C. perfringens of aquatic origin may arise from transmission in the terrestrial environment or from antibiotic contamination of the aquaculture environment and is of public health significance.

Genomic analysis and experimental pathogenic characterization of Riemerella anatipestifer isolates from chickens in China.

Waterfowl have a high likelihood of being infected with Riemerella anatipestifer. Although the pathogen is found in domestic ducks, turkeys, geese, and wild birds, there is little information available about the consequences of infection during egg laying and hatching in chickens. Here, we present the first report of a novel sequence type of R. anatipestifer S63 isolated from chickens in China. On the basis of pan-genome analysis, we showed S63's genome occupies a distinct branch with other R. anatipestifer isolates from other hosts. Galleria mellonella larval tests indicated that S63 is less virulent than R. anatipestifer Ra36 isolated from ducks. Ducks and hens are susceptible to S63 infection. There is no mortality rate for chickens or ducks, but adult chickens experience neurological symptoms that reduce egg production and hatching rates. In chickens, S63 might be passed vertically from parents to offspring, resulting in "jelly-like" lifeless embryos. Using quantitative PCR, S63 was detected in the brain, liver, reproductive organs, and embryos. As far as we know, this is the first report of R. anatipestifer in hens, a disease that can reduce egg productivity, lower hatching rates, and produce jelly-like lifeless embryos, and the first report to raise the possibility that hens can be infected by roosters via semen.

Characterization, taxonomic classification, and genomic analysis of two newly isolated bacteriophages with potential to infect Escherichia coli.

Escherichia coli is a pathogenic bacterium that is widely distributed and can lead to serious illnesses in both humans and animals. As there is rising incidence of multidrug resistance among these bacteria, it has become imperative to discover alternative therapies beyond antibiotics to effectively treat such infections. Bacteriophage (phage) therapy has the potential to treat infections caused by E. coli, as phages contain enzymes that can cause lysis or destruction of bacterial cells. Simultaneously, the easy accessibility and cost-effectiveness of next-generation sequencing technologies have led to the accumulation of a vast amount of phage sequence data. Here, phages IME177 and IME267 were isolated from sewage water of a hospital in China. Modern phylogenetic approaches and key findings from the genomic analysis revealed that phages IME177 and IME267 are classified as members of the Kayfunavirus genus, Autographiviridae family, and a newly proposed Suseptimavirus genus under subfamily Gordonclarkvirinae, respectively. Further, the Kuravirus genus reshaped into three different genera: Kuravirus, Nieuwekanaalvirus, and Suspeptimavirus, which are classified together under a higher taxonomic rank (subfamily) named Gordonclarkvirinae. No genes related to virulence were detected in the genomes of the phages IME177 and IME267. Both phages exhibited a high degree of resilience to a wide range of conditions, including pH, temperature, exposure to chloroform, and UV radiation. Phages IME177 and IME267 are promising biological agents that can infect E. coli, making them suitable candidates for use in phage therapies.IMPORTANCEBiological and taxonomic characterization of phages is essential for facilitating the development of effective strategies for phage therapy and disease control. Escherichia coli phages are incredibly diverse, and their isolation and classification help us understand the scope and nature of this diversity. By identifying new phages and grouping them into families, we can better understand the genetic and structural variations between phages and how they affect their infectivity and interactions with bacteria. Overall, the isolation and classification of E. coli phages have broad implications for both basic and applied research, clinical practice, and public health.

Genome sequence of Shiga toxin-producing Escherichia coli jumbo bacteriophage vB_EcoM_JNE01.

Bacteriophage vB_EcoM_JNE01 was isolated from chicken farm sewage using Escherichia coli O157:H7 as the host bacteria. The total length of the vB_EcoM_JNE01 genome is 355,583 bp, with 584 open reading frames and 36% G+C content. It shares an 80% nucleotide identity with 59% query coverage with the bacteriophage PBECO4 (NC_027364).

Phage Tail Fiber Protein as a Specific Probe for Recognition of Shiga Toxin-Producing Escherichia coli O91, O103, and O111.

The ability to quickly identify specific serotypes of Shiga toxin-producing Escherichia coli (STEC) could facilitate the monitoring and control of STEC pathogens. In this study, we identified the receptors and receptor-binding proteins (RBPs) of three novel phages (pO91, pO103, and pO111) isolated from hospital wastewater. Recombinant versions of these RBPs (pO91-ORF43, pO103-ORF42, and pO111-ORF8) fused to a fluorescent reporter protein were then constructed. Both fluorescence microscopy and transmission electron microscopy showed that all three recombinant RBPs were bound to the bacterial surface. Indirect enzyme-linked immunosorbent assay was used to verify that each recombinant RBP bound specifically to E. coli O91, O103, or O111, but not to any of the 83 strains of E. coli with different O-antigens, nor to 10 other bacterial species that were tested. The recombinant RBPs adsorbed to their respective host bacteria within 10 min of incubation. The minimum concentration of bacteria required for detection by the recombinant RBPs was 33 colony-forming units (CFU)/mL (range: 3.3 × 10 to 3.3 × 108 CFU/mL). Furthermore, each recombinant RBP was also able to detect bacteria in lettuce, chicken breast meat, and infected mice, indicating that their usage will facilitate the detection of STEC and may help to reduce the spread of STEC-related infections and diseases.

Phage Endolysins: Advances in the World of Food Safety.

As antimicrobial resistance continues to escalate, the exploration of alternative approaches to safeguard food safety becomes more crucial than ever. Phage endolysins are enzymes derived from phages that possess the ability to break down bacterial cell walls. They have emerged as promising antibacterial agents suitable for integration into food processing systems. Their application as food preservatives can effectively regulate pathogens, thus contributing to an overall improvement in food safety. This review summarizes the latest techniques considering endolysins' potential for food safety. These techniques include native and engineered endolysins for controlling bacterial contamination at different points within the food production chain. However, we find that characterizing endolysins through in vitro methods proves to be time consuming and resource intensive. Alternatively, the emergence of advanced high-throughput sequencing technology necessitates the creation of a robust computational framework to efficiently characterize recently identified endolysins, paving the way for future research. Machine learning encompasses potent tools capable of analyzing intricate datasets and pattern recognition. This study briefly reviewed the use of these industry 4.0 technologies for advancing the research in food industry. We aimed to provide current status of endolysins in food industry and new insights by implementing these industry 4.0 strategies revolutionizes endolysin development. It will enhance food safety, customization, efficiency, transparency, and collaboration while reducing regulatory hurdles and ensuring timely product availability.

Application of the Intelligent High-Throughput Antimicrobial Sensitivity Testing/Phage Screening System and Lar Index of Antimicrobial Resistance.

To improve the efficiency of antimicrobial susceptibility testing (AST) and phage high-throughput screening for resistant bacteria and to reduce the detection cost, an intelligent high-throughput AST/phage screening system, including a 96-dot matrix inoculator, image acquisition converter, and corresponding software, was developed according to AST criteria and the breakpoints of resistance (R) formulated by the Clinical & Laboratory Standards Institute (CLSI). AST and statistics of minimum inhibitory concentration (MIC) distributions (from R/8 to 8R) of 1,500 Salmonella strains isolated from poultry in Shandong, China, against 10 antimicrobial agents were carried out by the intelligent high-throughput AST/phage screening system. The Lar index, meaning "less antibiosis, less resistance and residual until little antibiosis", was obtained by calculating the weighted average of each MIC and dividing by R. This approach improves accuracy in comparison with using the prevalence of resistance to characterize the antimicrobial resistance (AMR) degree of highly resistant strains. For the strains of Salmonella with high AMR, lytic phages were efficiently screened from the phage library by this system, and the lysis spectrum was computed and analyzed. The results showed that the intelligent high-throughput AST/phage screening system was operable, accurate, highly efficient, inexpensive, and easy to maintain. Combined with the Shandong veterinary antimicrobial resistance monitoring system, the system was suitable for scientific research and clinical detection related to AMR.

Characterization of the Clostridium perfringens phage endolysin cpp-lys and its application on lettuce.

Clostridium perfringens is an important foodborne pathogen that can have severe consequences, including mortality and economic losses. In this study, the gene encoding cpp-lys, an endolysin from the C. perfringens phage cpp has been cloned and overexpressed. The encoded protein was characterized, and then its efficacy in controlling C. perfringens on lettuce was evaluated. The endolysin cpp-lys presented lytic activity against seven strains of C. perfringens that produce different types of toxins. It maintained stability across a wide range of temperatures (4 °C - 50 °C), and demonstrated tolerance to varying pH levels (4-9). Storage of endolysin cpp-lys under room-temperature conditions (16 °C-25 °C) and cold-temperature conditions (4 °C, -20 °C, and -80 °C) for 30 days did not affect its lytic activity. However, the lytic activity of cpp-lys decreased by 40 % and 18 % after storage for 30 d at 42 °C and 37 °C, respectively. The endolysin cpp-lys did not display cytotoxic activity against normal eukaryotic cells. The bacterial viability on lettuce was significantly lower in the group treated with endolysin cpp-lys than in the PBS group, and >4-log of C. perfringens J1 were removed within 15 min. Cpp-lys plus Zn2+ inhibited the activity of cpp-lys. The EDTA-treated cpp-lys significantly reduced the number of bacteria by up to 0.6-log CFU compared with the endolysin cpp-lys group. The findings of this study demonstrated that endolysin cpp-lys has potential applications in controlling C. perfringens in the food industry.

Genome Sequence of Novel Clostridium perfringens Bacteriophage vB_CpeS-17DYC, Isolated from Wastewater in China.

Phage vB_CpeS-17DYC was isolated from wastewater from a poultry market using Clostridium perfringens strain DYC. The vB_CpeS-17DYC genome is 39,184 bp long, with 65 open reading frames and a GC content of 30.6%. It shared 93.95% nucleotide identity, with 70% query coverage, with Clostridium phage phiCP13O (GenBank accession number NC_019506.1). Virulence factor genes were not found in the vB_CpeS-17DYC genome.

Temperate phage influence virulence and biofilm-forming of Salmonella Typhimurium and enhance the ability to contaminate food product.

Salmonella is a food-borne zoonotic pathogen that threatens food safety and public health security. Temperate phages can influence bacterial virulence and phenotype and play an important role in bacterial evolution. However, most studies on Salmonella temperate phages focus on prophage induced by bacteria, with few reports on Salmonella temperate phages isolated in the environment. Moreover, whether temperate phages drive bacterial virulence and biofilm formation in food and animal models remains unknown. In this study, Salmonella temperate phage vB_Sal_PHB48 was isolated from sewage. TEM and phylogenetic analysis indicated that phage PHB48 belongs to the Myoviridae family. Additionally, Salmonella Typhimurium integrating PHB48 was screened and designated as Sal013+. Whole genome sequencing revealed that the integration site was specific and we confirmed that the integration of PHB48 did not change the O-antigen and coding sequences of Sal013. Our in vitro and in vivo studies showed that the integration of PHB48 could significantly enhance the virulence and biofilm formation of S. Typhimurium. More importantly, the integration of PHB48 significantly improved the colonization and contamination ability of bacteria in food samples. In conclusion, we isolated Salmonella temperate phage directly from the environment and systematically clarified that PHB48 enhanced the virulence and biofilm-forming ability of Salmonella. In addition, we found that PHB48 increased the colonization and contamination ability of Salmonella in food samples. These results indicated that the highly pathogenic Salmonella induced by temperate phage was more harmful to food matrices and public health security. Our results could enhance the understanding of the evolutionary relationship between bacteriophages and bacteria, and raise public awareness of large-scale outbreaks resulting from Salmonella virulence enhancement in food industry.

Phage-Derived Depolymerase: Its Possible Role for Secondary Bacterial Infections in COVID-19 Patients.

As of 29 July 2022, there had been a cumulative 572,239,451 confirmed cases of COVID-19 worldwide, including 6,390,401 fatalities. COVID-19 patients with severe symptoms are usually treated with a combination of virus- and drug-induced immuno-suppression medicines. Critical clinical complications of the respiratory system due to secondary bacterial infections (SBIs) could be the reason for the high mortality rate in COVID-19 patients. Unfortunately, antimicrobial resistance is increasing daily, and only a few options are available in our antimicrobial armory. Hence, alternative therapeutic options such as enzymes derived from bacteriophages can be considered for treating SBIs in COVID-19 patients. In particular, phage-derived depolymerases have high antivirulent potency that can efficiently degrade bacterial capsular polysaccharides, lipopolysaccharides, and exopolysaccharides. They have emerged as a promising class of new antibiotics and their therapeutic role for bacterial infections is already confirmed in animal models. This review provides an overview of the rising incidence of SBIs among COVID-19 patients. We present a practicable novel workflow for phage-derived depolymerases that can easily be adapted for treating SBIs in COVID-19 patients.

Disarm The Bacteria: What Temperate Phages Can Do.

In the field of phage applications and clinical treatment, virulent phages have been in the spotlight whereas temperate phages received, relatively speaking, less attention. The fact that temperate phages often carry virulent or drug-resistant genes is a constant concern and drawback in temperate phage applications. However, temperate phages also play a role in bacterial regulation. This review elucidates the biological properties of temperate phages based on their life cycle and introduces the latest work on temperate phage applications, such as on host virulence reduction, biofilm degradation, genetic engineering and phage display. The versatile use of temperate phages coupled with their inherent properties, such as economy, ready accessibility, wide variety and host specificity, make temperate phages a solid candidate in tackling bacterial infections.

Phage Engineering for Targeted Multidrug-Resistant Escherichia coli.

The lytic bacteriophages have potential application value in the treatment of bacterial infections. However, the narrow host spectrum of these phages limits their range of clinical application. Here, we demonstrate the use of scarless Cas9-assisted recombination (no-SCAR) gene-editing technology to regulate phage-host range. We used phage PHB20 as the scaffold to create agents targeting different multidrug-resistant Escherichia coli by replacing its phage tail fiber gene (ORF40). The engineered phages were polyvalent and capable of infecting both the original host bacteria and new targets. Phage-tail fiber genes can be amplified by PCR to construct a recombinant phage PHB20 library that can deal with multidrug-resistant bacteria in the future. Our results provide a better understanding of phage-host interactions, and we describe new anti-bacterial editing methods.

A Multifunctional Light-Driven Swimming Soft Robot for Various Application Scenarios.

The locomotor behavior of creatures in nature can bring a lot of inspiration for the fabrication of soft actuators. In this paper, we fabricated a bionic light-driven swimming soft robot that can perform grasping of tiny objects and achieve the task of object transfer. By adding carbon nanotubes (CNTs), the temperature-sensitive hydrogels can be endowed with light-responsive properties. The fabricated composite hydrogel structure can control the contraction and expansion of volume by light, which is similar to the contraction and diastole behavior of muscles. The oscillation of the fish tail and the grasping action of the normally closed micromanipulator can be achieved by the control of the irradiation of the xenon light source. The bending of the bionic arm can be controlled by the irradiation of a near-infrared (NIR) laser, which transforms the spatial position and posture of the micromanipulator. The proposed scheme is feasible for miniaturized fabrication and application of flexible actuators. This work provides some important insights for the study of light-driven microrobots and light-driven flexible actuators.

Exploring the Benefits of Metal Ions in Phage Cocktail for the Treatment of Methicillin-Resistant Staphylococcus aureus (MRSA) Infection.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is an important zoonotic pathogen worldwide. Infections due to MRSA are associated with higher mortality rates compared with methicillin-susceptible S. aureus. Meanwhile, bacteriophages have been shown to overcome the emergence of MRSA. Methods: Phage PHB22a, PHB25a, PHB38a, and PHB40a were isolated. Here, we evaluated the ability of a phage cocktail containing phages PHB22a, PHB25a, PHB38a, and PHB40a against MRSA S-18 strain in vivo and in vitro. Phage whole-genome sequencing, host-range determination, lytic activity, and biofilm clearance experiments were performed in vitro. Galleria mellonella larvae and a mouse systemic infection model to evaluate the efficacy of phage therapy in vivo. Results: The phage cocktail exhibited enhanced antibacterial and anti-biofilm effects compared to the single phage. Phage cocktail contained with Ca2+/Zn2+ significantly reduced the number of viable bacteria (24-h or 48-h biofilm) by more than 0.81-log compared to the phage cocktail alone. Furthermore, we demonstrated that the addition of Ca2+ and Zn2+ phage cocktail could increase the survival rate of G. mellonella larvae infected with S. aureus by 10% compared with phage cocktail alone. This was further confirmed in the mouse model, which showed a 2.64-log reduction of host bacteria S-18, when Ca2+ and Zn2+ were included in the cocktail compared with the phage cocktail alone. Conclusion: Our results indicated that phage cocktail supplemented with Ca2+/Zn2+ could effectively remove bacteria in biofilms and mice tissues infected with S. aureus.

Recent advances in acoustic microfluidics and its exemplary applications.

Acoustic-based microfluidics has been widely used in recent years for fundamental research due to its simple device design, biocompatibility, and contactless operation. In this article, the basic theory, typical devices, and technical applications of acoustic microfluidics technology are summarized. First, the theory of acoustic microfluidics is introduced from the classification of acoustic waves, acoustic radiation force, and streaming flow. Then, various applications of acoustic microfluidics including sorting, mixing, atomization, trapping, patterning, and acoustothermal heating are reviewed. Finally, the development trends of acoustic microfluidics in the future were summarized and looked forward to.

A temperate Siphoviridae bacteriophage isolate from Siberian tiger enhances the virulence of methicillin-resistant Staphylococcus aureus through distinct mechanisms.

The emergence and worldwide spread of Methicillin-resistant Staphylococcus aureus (MRSA) pose a threat to human health. While bacteriophages are recognized as an effective alternative to treat infections caused by drug resistant pathogens, some bacteriophages in particular the temperate bacteriophage may also influence the virulence of the host bacteria in distinct ways. In this study, we isolated a bacteriophage vB_Saus_PHB21 from an epidermal sample of Siberian tiger (Panthera tigris altaica) using an MRSA strain SA14 as the indicator. Our following laboratory tests and whole genome sequencing analyses revealed that vB_Saus_PHB21 was a temperate bacteriophage belonging to the Siphoviridae family, and this bacteriophage did not contain any virulence genes. However, the integration of PHB21 genome into the host MRSA increased the bacterial capacities of cell adhesion, anti-phagocytosis, and biofilm formation. Challenge of the lysogenic strain (SA14+) caused severe mortalities in both Galleria mellonella and mouse models. Mice challenged with SA14+ showed more serious organ lesions and produced higher inflammatory cytokines (IL-8, IFN-γ and TNF-α) compared to those challenged with SA14. In mechanism, we found the integration of PHB21 genome caused the upregulated expression of many genes encoding products involved in bacterial biofilm formation, adherence to host cells, anti-phagocytosis, and virulence. This study may provide novel knowledge of "bacteria-phage-interactions" in MRSA.

Insight-HXMT observations of jet-like corona in a black hole X-ray binary MAXI J1820+070.

A black hole X-ray binary produces hard X-ray radiation from its corona and disk when the accreting matter heats up. During an outburst, the disk and corona co-evolves with each other. However, such an evolution is still unclear in both its geometry and dynamics. Here we report the unusual decrease of the reflection fraction in MAXI J1820+070, which is the ratio of the coronal intensity illuminating the disk to the coronal intensity reaching the observer, as the corona is observed to contrast during the decay phase. We postulate a jet-like corona model, in which the corona can be understood as a standing shock where the material flowing through. In this dynamical scenario, the decrease of the reflection fraction is a signature of the corona's bulk velocity. Our findings suggest that as the corona is observed to get closer to the black hole, the coronal material might be outflowing faster.