Efficient antibacterial polyphosphazene material with potential to prominent wound healing

Reducing the toxicity of silver-based antibacterial agents used in gels and improving their biocompatibility are of great significance in the development of wound dressings. Thus, a highly crosslinked organic–inorganic hybrid porous polyphosphazene nanospheres (PRV-HMSs) were prepared via precipitation polymerization. The structures and properties were investigated. The results indicated that PRV-HMSs have uniform particle size about 500 nm, excellent thermal stability, high silver loading (26.5 wt.%) and remarkable sustained-release properties after loading AgNO3 (up to 2 weeks). The antibacterial effects were investigated with zone of inhibition testing, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), Live/Dead bacterial staining assay and bacterial growth curve assays. The silver-loaded nanospheres have excellent bactericidal effects for E. coli or S. aureus and an average bactericidal rate of 94.02% and 94.67% in the 120 hour long-acting antibacterial test. The cytotoxicity and laser confocal immunofluorescence staining experiments indicate that the simple combination of nanospheres and agar not only give low cytotoxicity, but also significantly promote the activation of macrophages, which showing potential application in the wound dressings based on hydrogel.

Comparison of E. coli based self-inducible expression systems containing different human heat shock proteins

IPTG-inducible promoter is popularly used for the expression of recombinant proteins. However, it is not suitable at the industrial scale due to the high cost and toxicity on the producing cells. Recently, a Self-Inducible Expression (SILEX) system has developed to bypass such problems using Hsp70 as an autoinducer. Herein, the effect of other heat shock proteins on the autoinduction of green fluorescent protein (EGFP), romiplostim, and interleukin-2 was investigated. For quantitative measurements, EGFP expression was monitored after double-transformation of pET28a-EGFP and pET21a-(Hsp27/Hsp40/Hsp70) plasmids into E.coli using fluorimetry. Moreover, the expression level, bacterial growth curve, and plasmid and expression stability were compared to an IPTG- inducible system using EGFP. Statistical analysis revealed a significant difference in EGFP expression between autoinducible and IPTG-inducible systems. The expression level was higher in Hsp27 system than Hsp70/Hsp40 systems. However, the highest amount of expression was observed for the inducible system. IPTG-inducible and Hsp70 systems showed more lag-time in the bacterial growth curve than Hsp27/Hsp40 systems. A relatively stable EGFP expression was observed in SILEX systems after several freeze–thaw cycles within 90 days, while, IPTG-inducible system showed a decreasing trend compared to the newly transformed bacteria. Moreover, the inducible system showed more variation in the EGFP expression among different clones than clones obtained by SILEX systems. All designed SILEX systems successfully self-induced the expression of protein models. In conclusion, Hsp27 system could be considered as a suitable autoinducible system for protein expression due to less metabolic burden, lower variation in the expression level, suitable plasmid and expression stability, and a higher expression level.

Application of liquid-infused membranes to mitigate biofouling

The novel liquid-infused membranes have been shown to mitigate membrane biofouling. Here, the long-term stability of these membrane have been tested and analyzed using bacterial growth curve models.

Biosurfactant Screening of Halomonas meridiana BK-AB4 for Microbial Enhanced Oil Recovery

Biosurfactant is produced by a certain microorganism to reduce surface tension. Microbial enhanced oil recovery (MEOR) is one of the many applications of biosurfactant. However, the biosurfactant for MEOR needs to be able to withstand the extreme environment of oil reservoirs with high temperature and high salinity. Halomonas meridiana BK-AB4 is a halophilic bacterium obtained from the Bledug Kuwu crater in Central Java, Indonesia. The similarity of both environment condition indicates the potential to produce suitable biosurfactant. This study evaluates the potential of Halomonas meridiana BK-AB4 in producing biosurfactant compared to several bacteria isolated from the crater. The blood agar test of Halomonas meridiana BK-AB4 exhibited greenish discoloration around the colony, indicating the ability of type α-hemolysis. The interfacial tension was measured using the Du Nouy ring method to represent the biosurfactant activity, with the results of 0.014 dyne/cm. These results showed that Halomonas meridiana BK-AB4 has a very good potential for producing biosurfactant for MEOR. The optimum time of the culture starter for production is 6 hours, as determined from the bacterial growth curve.

Analysis of Routine and Integrative Data from Clostridioides difficile Infection Diagnosis and the Consequent Observations

Background: Clostridioides difficile Infection (CDI) is an acute disease that needs a fast proper treatment. Unfortunately, the diagnosis, and above all the understanding of the results, remain arduous. Objective: This study analyzed routine and integrative results of all fecal samples from patients over time. Our aim was to understand the dynamics of CDI infection and the meaning of “difficult to interpret” results, to make physicians better understand the various tools they can use. Methods: We evaluated routine results obtained from 815 diarrheal stools with Enzyme Immunoassay (EIA) that detects C. difficile Glutamate Dehydrogenase (GDH) antigen and toxin B. We also reanalyzed a part of samples using integrative tests: a Real-time polymerase chain reaction (RT-PCR) for C. difficile toxin B gene (tcdB) and the automated immunoassay VIDAS C. difficile system for GDH and toxins A/B. Results: EIA GDH positivity increased through multiple testing over time, with a P value <0.001, depicting a sort of bacterial growth curve. Eighty-five percent of GDH positive/toxin B negative, i.e., discrepant, samples PCR were tcdB positive, 61.5% of discrepant tcdB positive samples were VIDAS toxins A/B positive, and 44.4% of GDH EIA negative stools were VIDAS GDH positive. Conclusion: The results confirmed the low sensitivity of the EIA system for C. difficile GDH and toxins, questioned the use of the latter for concluding any CDI diagnostic algorithm, and led us to indicate the algorithm beginning with tcdB molecular research, and continuing in positive cases with VIDAS CD GDH method, as the most effective for CDI.

Complete Genome Sequence and Characterization of a Polyethylene Biodegradation Strain, Streptomyces Albogriseolus LBX-2

A bacterial strain, Streptomyces albogriseolus LBX-2, was isolated from a soil sample in Chengdu, China. S. albogriseolus LBX-2 is an aerobic and Gram-positive microorganism that is capable of using the polyethylene as the sole carbon source. Results of scanning electron microscopy and tensile tests indicated that S. albogriseolus LBX-2 could cause the damages to polyethylene (PE). Suspension culture of LBX-2 resulted in the weight loss in the PE powder over a 15-day period. The bacterial growth curve assay clearly demonstrated the utilization of n-hexadecane and n-octadecane for the strain LBX-2. Phylogenetic analysis showed that it was grouped in the same clade as S. albogriseolus belonging to Streptomyces. The complete genome of strain LBX-2 consists of a chromosome of 7,210,477 bp and a linear plasmid of 336,677 bp. Compared with other strains of Streptomyces, the genome size of S. albogriseolus LBX-2 was smaller than the average but its guanine and cytosine content (72.47%) was higher than the others. The Non-Redundant Protein Database (NR), Kyoto Encyclopedia of Genes and Genomes (KEGG), SwissProt, Gene Ontology (GO) and Clusters of Orthologous Groups (COG) annotations provided information on the specific functions of encoded proteins. A total of 21 monooxygenase and 22 dioxygenase genes were found in its genome. Synteny comparison with the genome of Streptomyces coelicolor A3(2) revealed a low overall genetic diversity between them. This study provides valuable information to reveal the underlying mechanisms on PE degradation by S. albogriseolus LBX-2.

Panax Notoginseng Extract Possesses Significant Antibacterial Activity against Pathogenic Streptococci

Background: In traditional Chinese medicine, Panax notoginseng is used to treat inflammation and bleeding but has not been shown to affect bacterial pathogens. Objectives: Our aim was to assess the antibacterial potential of Panax notoginseng extract (PNE) against bacterial pathogens. Methods: PNE was dissolved in autoclaved distilled water. Antimicrobial activity was measured by the disc diffusion test and bacterial growth curve assays, in which the concentration of bacterial colony forming units was monitored at several time points in the presence or absence of PNE. Results: Disc diffusion and growth curve assays demonstrated that PNE significantly inhibited the growth of Streptococcus pyogenes, Streptococcus pneumoniae, and Haemophilus influenzae (p < 0.05). In contrast, the growth of the oral commensal bacteria Streptococcus intermedius, Streptococcus salivarius, and Streptococcus anginosus was not inhibited. Therefore, S. pyogenes clinical isolates were analyzed. PNE had antimicrobial effects on all tested isolates in both aerobic and anaerobic conditions. In addition, when S. pyogenes was co-cultured with S. intermedius in the presence of PNE, PNE inhibited the growth of S. pyogenes, but did not inhibit the growth of S. intermedius. Conclusion: Our findings suggested that PNE inhibited S. pyogenes without affecting oral commensal bacteria. Therefore, PNE could be used for the treatment of S. pyogenes infections.

Green Synthesis of Silver Nanoparticles for Antibacterial Application

Tomato, as a fresh or processed product,has a high nutritional value due to its content of bioactive components such as phenolic compounds. Tomato fruit juice is used as a reducing and capping agents for the biosynthesis of silver nano particles (AgNPs). Ultraviolet spectroscopic analysis offered peaks in the range of 396‒420 nm that indicate the production of AgNPs. Silver in ionic or nanoparticle forms has a high antimicrobial activity and is therefore widely used for various sterilization purposes including materials of medical devices and water sanitization. The Scanning electron microscopy images showed that the particles were of mostly spherical shape and confirms the size of NPs that varies from 10 to 30 nm. the bacteriological tests of AgNPs also showed good antibacterial activity against(Escherichia coli)The efficacious bioactivities indicate that the tomato AgNPs can be used efficiently in pharmaceutical and medical industries. The aqueous extract of Lycopersicon esculentum (red tomato) was used for the rapid synthesis of AgNP,which is very simple and eco-friendly in nature. The UV-visible spectroscopy technique was employed to establish the formation of AgNP. For the bacteriological tests,the microorganism E. coli,were inoculated on Luria broth (LB) agar plate in the presence of varied amounts of AgNP. The antibacterial activity was obvious from the zone of inhibition. At concentration 50 μg/ml and above,the AgNP showed a clear zone of inhibition and the minimum inhibitory concentration of AgNP was 20 μg/ml. From the slope of the bacterial growth curve,it has been concluded that the nanoparticles are bacteriostatic at low concentration and bactericidal at high concentration. Therefore,these nanoparticles are believed to act as preventive for bacterial contamination.