Indoor Screening of Bactericides against Kiwifruit Bacterial Canker

[ Objective ] The paper was to screen the effective agents against kiwifruit bacterial canker in Wanzhou District of China. [ Method ] Ten kinds of com- mon commercial bactericides preliminarily screened were selected for indoor antibacterial test using paper plate method and plate streaking method, and six kinds of bactericides with good antibacterial effects were further screened for indoor toxicity test. [ Result] Chloramphenicoloethylicin had the best antibacterial effect, with EC50 of 36.34 rag/L; followed by Xintianxlucai No. 6 and embamycin, with EC50 of 83.21 and 92.34 mg/L, respectively. [ Conclusion] Cldoramphenicoloethylicin, Xintianxiucai No. 6 and embamycin screened in the test had good antibacterial effect against kiwifruit bacteriai canker in Wanzhou District, and chlorampheni- coleethylicin was the most effective agent. These three agents could be directly applied to control kiwifruit bacterial canker in production, while application time and climate conditions in fields should also be considered during the actual application process. It is suggested that three agents can be used alternatively in order to de- lay the resistance of plants.

Identification,Characterization,and Probiotic Potentials of Lactobacillus pentosus SF-1

In recent years probiotics have been considered as a potential substitution of antibiotics to control pathogens and treat infectious diseases in aquaculture.In the present study a strain of Lactobacillus pentosus,named as L.pentosus SF-1,was isolated from waters in aquaculture.The species identification of this strain was conducted by 16S rRNA sequence,and the physiological and biochemical characteristics of this strain were assessed.Furthermore,the virulence,antibiotic sensitivity,cell surface characteristics and acid/base-resistance of L.pentosus SF-1 were determined to evaluate the probiotic potentials of this strain.Specifically,L.pentosus SF-1 is sensitive to most common antibiotics,and no hemolysin was generated from it,indicating the safety of this strain to hosts.In addition,L.pentosus SF-1 was able to tolerate the artificial gastric juice at pH 3 for 4 h and the artificial intestinal fluid at pH 6.8 or 8.0 for 6 h.Moreover,the analysis of self-aggregation and the adhesion of L.pentosus SF-1 to organic solvents suggested a high potential of L.pentosus SF-1 to inhabit the hosts,which was confirmed by testing the colonization of L.pentosus SF-1 in germ-free zebrafish.Interestingly,L.pentosus SF-1 displayed a high bactericidal activity against several bacterial pathogens.Consistently,the incubation of L.pentosus SF-1 significantly promoted the expression of antimicrobial components in zebrafish,contributing to the protection of the fish from E.tarda infection in vivo.Taken together,the probiotic strain L.pentosus SF-1 could be applied as anti-infection reagent in aquaculture.

Excellent lubricating hydrogels with rapid photothermal sterilization for medical catheters coating

Bacterial infection and tissue damage caused by friction are two major threats to patients’health in medical catheter implantation.Hydrogels with antibacterial and lubrication effects are competitive candidates for catheter coating materials.Photothermal therapy(PTT)is a highly efficient bactericidal method.Here,a composite hydrogel containing MXene nanosheets and hydrophilic 3-sulfopropyl methacrylate potassium salt(SPMK)is reported,which is synthesized through the one-pot method and heat-initiated polymerization.The hydrogel shows excellent antibacterial performance against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)in 3 min in the air or 20 min in the water environment under near-infrared light(NIR;808 nm)irradiation.The friction coefficient of the hydrogel is about 0.11,which is 48%lower than that without SPMK.The rapid photothermal sterilization is attributed to the outstanding antibacterial ability and thermal effect of photoactivated MXene.The ultra-low friction is the result of the hydration lubrication mechanism.This study provides a potential strategy for the surface coatings of biomedical catheters,which enables rapid sterilization and extremely low interface resistance between catheters and biological tissues.

Different bactericidal abilities of plasma-activated saline with various reactive species prepared by surface plasma-activated air and plasma jet combinations

Plasma-activated water(PAW),as an extended form of cold atmospheric-pressure plasma,greatly expands the application of plasma-based technology.The biological effects of PAW are closely related to the aqueous reactive species,which can be regulated by the activation process.In this study,surface plasma-activated air(SAA)and a He+O_(2)plasma jet(Jet)were parallelly combined(the SAA+Jet combination)or sequentially combined(the SAA→Jet combination and the Jet→SAA combination)to prepare plasma-activated saline(PAS).The PAS activated by the combinations exhibited stronger bactericidal effects than that activated by the SAA or the Jet alone.The concentrations of H_(2)O_(2)and NO_(2)^(-)were higher in the PAS activated by the Jet→SAA combination,while ONOO^(-)concentrations were close in the three kinds of PAS and^(1)O_(2)concentrations were higher in the PAS activated by the SAA+Jet combination.The analysis of scavengers also demonstrated that H_(2)O_(2),^(1)O_(2),and ONOO^(-)in the PAS activated by the SAA+Jet combination,and^(1)O_(2)in the PAS activated by the Jet→SAA combination played critical roles in bactericidal effects.Further,the effective placement time of the three PAS varied,and the PAS activated by the Jet→SAA combination could also inactivate 2.6-log_(10)of MRSA cells after placement for more than 60 min.The regulation of reactive species in plasma-activated water via different combinations of plasma devices could improve the directional application of plasma-activated water in the biomedical field.

Anti-infective immune functions of type Ⅳ interferon in grass carp(Ctenopharyngodon idella):A novel antibacterial and antiviral interferon in lower vertebrates

Type Ⅳ interferon(IFN-υ)is a recently discovered cytokine crucial for host defense against viral infections.However,the role and mechanisms of IFN-υin bacterial infections remain unexplored.This study investigated the antibacterial and antiviral functions and mechanisms of grass carp(Ctenopharyngodon idella)IFN-υ(CiIFN-υ)both in vivo and in vitro.The CiIFN-υgene was first identified and characterized in grass carp.Subsequently,the immune expression of CiIFN-υsignificantly increased following bacterial challenge,indicating its response to bacterial infections.The eukaryotic recombinant expression plasmid of CiIFN-υwas then constructed and transfected into fathead minnow(FHM)cells.Supernatants were collected and incubated with four bacterial strains,followed by plate spreading and colony counting.Results indicated that CiIFN-υexhibited more potent antibacterial activity against gram-negative bacteria compared to gram-positive bacteria and aggregated gram-negative bacteria but not gram-positive bacteria.In vivo experiments further confirmed the antibacterial function,showing high survival rates,low tissue edema and damage,reduced tissue bacterial load,and elevated proinflammatory response at the early stages of bacterial infection.In addition,the antiviral function of CiIFN-υwas confirmed through in vitro and in vivo experiments,including crystal violet staining,survival rates,tissue viral burden,and reverse transcription-quantitative real-time polymerase chain reaction(RT-qPCR).This study highlights the antibacterial function and preliminary mechanism of IFN-υ,demonstrating that IFN-υpossesses dual functions against bacterial and viral infections.

Preparation and Application of Natural Bactericidal Deodorizer

Jasmine essential oil and lemon essential oil were selected for deodorizing ingredient.Lysine and silver ions were selected as auxiliary raw material.The product was prepared by emulsion dissolution technology.The minimum inhibitory concentration of various bacteria were during 100~2,000 mg/L.In the test,the germicidal efficiency of 2.0%(w/w)deodorant was 99%.The removal efficiency of trimethylamine and methanthiol were more than 95%by 3.0%(w/w).deodorant.The removal efficiency of ammonia and methanthiol were more than 92%by 3.0%(w/w)deodorant.In addition,The removal efficiency of isovaleric acid was 98%by 2.0%(w/w)deodorant.In analysis result,common pathogenic bacteria were effectively suppressed,kitchen and toilet odors were efficiently removed by natural plant deodorant.

In Vitro Anti-Bacterial and Anti-Fungal Activities of Extracts from Different Parts of 7 Zingiberaceae Plants

This study aimed to explore the anti-bacterial and anti-fungal activities of extracts from different parts of plants in the Zingiberaceae family.The inhibitory rate,minimum inhibitory concentration(MIC),and minimum bactericidal concentration(MBC)of leaf and stem,and root and rhizome extracts from Alpinia katsumadai Hayata,Alpinia oxyphylla Miq×Alpinia henryi K.Schumann,Alpinia oblongifolia Hayata,Alpinia nigra(Gaertn.)Burtt,Amomum villosum Lour,Alpinia zerumbet(Pers.)Burtt.et Smith and Alpinia oxyphylla Miq were determined using the fungus cake method and double dilution method.The seven Zingiberaceae plants exhibited characteristic antibacterial activities against pathogenic bacteria and fungi.At a 1.5 mg mL^(−1),A.zerumbet root and rhizome extracts exhibited strong inhibitory activity against S.aureus and E.coli,with 83.23%and 79.62%,respectively.In addition,A.zerumbet leaf and stem extracts had an inhibitory rate of 90.85%against P.aeruginosa.At the same concentration,the leaf and stem,root and rhizome extracts of A.katsumadai had the best anti-bacterial effect against F.oxysporum,with inhibition rates of 84.46%and 84.73%,respectively.Moreover,A.katsumadai and A.zerumbet leaf and stem extracts had the most significant antibacterial effect against S.aureus,with a MIC of 0.063 mg mL^(−1).Thus,both A.katsumadai and A.zerumbet extracts had significant antibacterial activity.In addition,by comparing the inhibitory effect of extracts from different parts,it was found that the inhibitory rate and average inhibitory rate of extracts from leaf and stem were higher than those from root and rhizome.The chemical constituents of A.katsumadai and A.zerumbet,determined by the high-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS),revealed that citric acid(CA),alpinetin,and pinocembrin(PNCB)were the functional constituents yielding the antibacterial activity.Overall,A.katsumadai and A.zerumbet have the potential to be developed as new plant fungicides and bactericides.

Ultra-Violet (UV): A Good Bacterial Sterilizer?

Introduction: The aim of this study was to improve the DISTER-UV and to perform microbiological quality control at the biomedical laboratory of the West African Polytechnic University from January 2022 to November 2022. Methodology: During this eleven-month prospective study, we set up a quality control device (QCD). For microbiological quality control, we performed different cultures of bacteria with different bacteriological and morphological characteristics at T0 (no sterilization) and at T30 (after 30 minutes of sterilization under DISTER-UV). Results: After the realization, the DCQ attached to the DISTER-UV1 allows to display of the UV wavelength present in the light box. This device also displays and alerts when the UV intensity emitted by the lamps is below 250 nm. During microbiological quality control, the cultures carried out at T30 and incubated for 24 hours did not reveal any bacterial colonies. This shows the bactericidal character of DISTER-UV-2. Conclusion: The improvement and the microbiological quality control allowed us to switch from DISTER-UV1 (without sensor) to DISTER-UV-2 (with sensor or DCQ). The biological control allowed us to affirm that the DISTER-UV-2 is bactericidal.

在线凝胶色谱串联气相色谱-质谱对食品中七种杀菌剂残留量的测定

The determination of 7 bactericidals residues,including chlorthalonil,dichlofluanid,tolylfluanid,captan,folpet,captafol and deltamethrin,in foods by using on-line gel permeation chromatography(GPC) coupled with gas chromatography-mass spectrometry(GC-MS).Bactericidal residues were extracted with acetonitrile,and cleaned up by ENVI-Crab,LC-NH2 column and GPC,respectively.The analysis of 7 bactericidals residues was performed by GC-MS.The average recoveries of analytes were range of 75%-120% with RSD of 3.5%-10.3%.

Antibacterial Performance of Protective and Decorative Deposits

By way of bactericidal halo test, the antibacterial performance of various electroplated deposits (cobalt, zinc, copper, silver, gold, nickel, chromium, cobalt-containing alloy of nickel, and nickel-containing alloy of cobalt) were determined. The results of the test show that the electroplated deposits of zinc, cobalt, cobalt-containing alloy of nickel, and nickel-containing alloy of cobalt, silver and copper possess a distinct antibacterial capability against the growth of pathogenic bacteria tested, and that SUS304 stainless steel and chromium deposit have no antibacterial activity. The relationship between the antibacterial capability and the rest potentials of the deposits was investigated. It was found that the higher the antibacterial activity of the electroplated deposit was, the more negative the rest potential of deposit was.

Effect of Degree of ClO‾Hypochlorite on the Wet Synthesis of Ferrate (VI)

This work is a result of previously done studies on the synthesis of A2FeVIO4 wet ferrate (VI) formula, using chlorine as an oxidant. The major problem of these ferrates is related to their stability over time. This brings us to identify and optimize the critical parameters influencing the preparation of the Na2FeO4 at room stable phase with acceptable performance. The use of water bleach (hypochlorite ClO‾) at a chlorometric degree of 50°F in the synthesis of the Na2FeO4 ambient stable phase promotes the oxidation of iron (II) iron to (VI) in a concentrated NaOH alkaline medium. The synthesis reaction is in the presence of FeSO4 7H2O hydrated iron sulfate at a temperature of about 55°C in order to simplify the synthesis process, to enhance the production of the Fe (VI) and to meet the growing demand of ferrates (VI) for their interest in the treatment of water. Monitoring the degradation of synthesized Na2FeO4 shows its stability up to 12 months, which facilitates storage and transportation. The phases obtained were characterized by IR spectroscopy, and RX by UV spectrophotometer, measuring the optical density at 507 nm.

Antibacterial activity of honey against clinical isolates of Escherichia coli,Pseudomonas aeruginosa and Salmonella enterica serovar Typhi

Objective:To ascertain the potential antibacterial activity of honey against clinical isolates of Escherichia coli(E.coli),Pseudomonas aeruginosa(P.aeruginosa) and Salmonella enterica serovar Typhi(S.enterica serovar Typhi) by in vitro methods.Methods:The partial inhibitory concentration(PIC),minimum inhibitory concentration(MIC) and minimum bactericidal concentration(MBC) values of the autoclaved honey(extracted from Apis indica hive by indigenous method) were determined for S.enterica serovar Typhi(n=8:from blood cultute), E.coli(n=5:from urine culture) and P.aeruginosa(n=5:from pus culture) isolates by in vitro methods.Results:The PICs of the honey tested for the isolates ranged 0.50%-1.25%(v/v) for S. enterica serovar Typhi,0.75%-1.50%(v/v) for E.coli and 1.00%-1.25%(v/v) for P.aeruginosa, while the MICs ranged 1.75%-3.00%(v/v),3.00%-3.50%(v/v) and 3.50%(v/v),respectively.The P.aeruginosa and E.coli isolates had MBC value of 4.00%(v/v):the S.enterica serovar Typhi showed MBCs in between 3.00%and 3.50%(v/v).The bactericidal activity of honey was achieved at concentration 3.00%(v/v) for S.enterica serovar Typhi and E.coli,and at 3.50%(v/v) for P. aeruginosa.Conclusions:The excellent antibacterial activity of honey against clinical bacterial isolates indicates the usefulness of honey in clinical practice against bacterial infection.

Anti-Helicobacter pylori activities of Chenopodium ambrosioides L. in vitro and in vivo

AIM: To investigate the bactericidal effects of Chenopodium ambrosioides L.(CAL) against Helicobacter pylori(H.pylori) both in vitro and in vivo.METHODS: For in vitro experiments, the inhibitory activity of CAL was tested using an agar dilution method; H.pylori strain NCTC11637 was incubated on Columbia blood agar plates containing serial concentrations of CAL.The minimal inhibitory concentration(MIC) was determined by the absence of H.pylori colonies on the agar plate.Time-kill curves were used to evaluate bactericidal activity; the average number of colonies was calculated at 0, 2, 8 and 24 h after liquid incubation with concentrations of CAL at 0.5, 1, and 2 × MIC.For in vivo experiments, H.pylori-infected mice were randomly divided into CAL, triple therapy(lansoprazole, metronidazole, and clarithromycin), blank control, or H.pylori control groups.The eradication ratios were determined by positive findings from rapid urease tests(RUTs) and by histopathology.RESULTS: In vitro, the MIC of CAL against H.pylori was 16 mg/L.The time-kill curves showed a stable and persistent decreasing tendency with increasing CAL concentration, and the intensity of the bactericidal effect was proportional to dose; the 1 and 2 × MIC completely inhibited the growth of H.pylori at 24 h.In vivo, the eradication ratios in the CAL group were60%(6/10) by RUT and 50%(5/10) by histopathology.Ratios in the triple therapy group were both 70%(7/10), and there was no difference between the CAL and triple therapy groups.Histopathologic evaluation revealed massive bacterial colonization on the surface of gastric mucosa and slight infiltration of mononuclear cells after inoculation with H.pylori, but no obvious inflammation or other pathologic changes in gastric mucosa of mice from CAL and triple therapy groups.CONCLUSION: CAL demonstrates effective bactericidal activity against H.pylori both in vitro and in vivo.

TiO_2 thin film photocatalyst

It is well known that the photocatalytic activity of TiO_2 thin filmsstrongly depends on the preparing methods and post-treatment conditions, since they have a decisiveinfluence on the chemical and physical properties of TiO_2 thin films. Therefore, it is necessary toelucidate the influence of the preparation process and post-treatment conditions on thephoto-catalytic activity and surface microstructures of the films. This review deals with thepreparation of TiO_2 thin film photo-catalysts by wet-chemical methods (such as sol-gel,-reversemicellar and liquid phase deposition) and the comparison of various preparation methods as well astheir advantage and disadvantage. Furthermore, it is discussed that the advancement ofphotocatalytic activity, super-hydrophilicity and bactericidal activity of TiO_2 thin filmphotocatalyst in recent years.

Combined antibacterial activity of stingless bee(Apis mellipodae)honey and garlic(Allium sativum)extracts against standard and clinical pathogenic bacteria

Objective:To investigate the synergic antibacterial activity of garlic and tazma honey against standard and clinical pathogenic bacteria.Methods:Antimicrobial activity of tazma honey,garlic and mixture of them against pathogenic bacteria were determined.Chloramphenicol and water were used as positive and negative controls,respectively.Minimum inhibitory concentration(MIC)and minimum bactericidal concentration of antimicrobial samples were determined using standard methods.Results:Inhibition zone of mixture of garlic and tazma honey against all tested pathogens was significantly(P≤0.05)greater than garlic and tazma honey alone.The diameter zone of inhibition ranged from(18±1)to(35±1)mm for mixture of garlic and tazma honey,(12±1)to(20±1)nun for tazma honey and(14±1)to(22±1)mm for garlic as compared with(10±1)to(30±1)mm for chloramphenicol.The combination of garlic and tazma honey(30-35 mm)was more significantly(P≤0.05)effective against Salmonella(NCTC 8385),Staphylococcus aureus(ATCC 25923),Lyesria moncytogenes(ATCC 19116)and Streptococcus pneumonia(ATCC 63).Results also showed considerable antimicrobial activity of garlic and tazma honey.MIC of mixture of garlic and tazma honey at 6.25%against total test bacteria was 88.9%.MIC of mixture of garlic and tazma honey at6.25%against Gram positive and negative were 100%and 83.33%,respectively.The bactericidal activities of garlic,tazma honey,and mixture of garlic and tazma honey against all pathogenic bacteria at 6.25%concentration were 66.6%,55.6%and 55.6%,respectively.Conclusions:This finding strongly supports the claim of the local community to use the combination of tazma honey and garlic for the treatment of different pathogenic bacterial infections.Therefore,garlic in combination with tazma honey can serve as an alternative natural antimicrobial drug for the treatment of pathogenic bacterial infections.Further in vivo study is recommended to come up with a comprehensive conclusion.

In vitro control of Staphylococcus aureus (NCTC 6571) and Escherichia coli (ATCC 25922) by Ricinus communis L.

Objective:To evaluate antibacterial activity of hot and cold ethanol and methanol leaf extracts of Ricinus communis L(R.communis)against Staphylococcus aureus(S.aureus)(NCTC 6571)and Escherichia coli(E.coli)(ATCC 25922).Methods:Leaf powder of R.communis L.was extracted with hot(in Soxhlet)and cold ethanol and methanol,separately.The antibacterial activity of the extracts was determined by agar well diffusion and macro broth dilution methods.The extracts were also subjected to phytochemical analysis.Results:All the four test extracts showed inhibition on both S.aureus and E.coli.Hot and cold ethanol extracts revealed significantly(P<0.05)higher inhibition on S.aureus than methanol extracts,and the hot ethanol extract had the lowest minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)values(5 mg/mL and 10 mg/mL,respectively).E.coli was highly inhibited by hot extracts of both ethanol and methanol with the MIC and MBC of 40 mg/mL and 80 mg/mL,respectively.Phytochemical analysis revealed the presence of saponins,cardiac glycosides,tannins,flavonoids and terpenoids in all test extracts.Conclusions:This study demonstrates that the hot and cold methanol and ethanol extracts are potential sources for control of S.aureus and E.coli.Especially,the hot and cold extracts of ethanol are more inhibitive against 5.aureus even at lower concentration.Further study is needed to identify the specific bioactive compounds,their mode of action and their nontoxic nature in vivo condition.

Biological Stability of Water-Based Cutting Fluids:Progress and Application

The application of cutting fluid in the field of engineering manufacturing has a history of hundreds of years,and it plays a vital role in the processing efficiency and surface quality of parts.Among them,water-based cutting fluid accounts for more than 90%of the consumption of cutting fluid.However,long-term recycling of water-based cutting fluid could easily cause deterioration,and the breeding of bacteria could cause the cutting fluid to fail,increase manufacturing costs,and even endanger the health of workers.Traditional bactericides could improve the biological stability of cutting fluids,but they are toxic to the environment and do not conform to the development trend of low-carbon manufacturing.Low-carbon manufacturing is inevitable and the direction of sustainable manufacturing.The use of nanomaterials,transition metal complexes,and physical sterilization methods on the bacterial cell membrane and genetic material could effectively solve this problem.In this article,the mechanism of action of additives and microbial metabolites was first analyzed.Then,the denaturation mechanism of traditional bactericides on the target protein and the effect of sterilization efficiency were summarized.Further,the mechanism of nanomaterials disrupting cell membrane potential was discussed.The effects of lipophilicity and the atomic number of transition metal complexes on cell membrane penetration were also summarized,and the effects of ultraviolet rays and ozone on the destruction of bacterial genetic material were reviewed.In other words,the bactericidal performance,hazard,degradability,and economics of various sterilization methods were comprehensively evaluated,and the potential development direction of improving the biological stability of cutting fluid was proposed.

Studies on the Antibacterial Activity of the Extract of Stachytarpheta angusti folia

To investigate the scientific bases for t/te traditional use of Stachy-tarpheta angustifolia. Methods: In vitro antibacterial activity of the aqueous and ethanol extract of the plant was investigated using the agar cup plate diffusion method. Results: The ethanol extract of the plant showed antibacterial activity against Escherichia coli, Streptococcus faecalis, Shigella dysenterme, Slaphylococcus aureus (S. aureus) , Salmonella sp. , Pseudomonas aeruginosa and Neisseria gonor-r/iaeae, while the water extract was active against Escherichia coli, Streptococcus faecalis, Shigella dysenterme, Sta-phylococcus aureus and. Pseudomonas aeruginosa. The etlianol extract exhibited higher antibacterial activity than the water extract. The minimum inhibitory concentration (MIC) and minimum bactericidal, concentration (MBC} of the ethanol extract were 0. 65 mg/mt and 0. 85 mg/ml, respectively , against S. aureus. Treatment of the extract at higher temperature, 60℃ increased the sensitivity of the test organisms to the plant extract. Phytochemical analysis indicated t/tat the plant possesses tannins, saponins as well as phenols. Conclusion: A scientific basis exists that the plant possesses antibacterial activity and it could be a probable source of therapeutic agent.

Bactericidal/permeability-increasing protein originates in both the testis and the epididymis and localizes in mouse spermatozoa

Bactericidal/permeability-increasing protein （BPI） is an endogenous antibiotic protein with activity against gram-negative bacteria. In the present study, we examined the expression of BPI in postnatal mouse testes and epididymides as well as the subcellular localization within epididymal spermatozoa. Our results showed that, BPI mRNA was expressed in testis and epididymis independently. Throughout the epididymis, the BPI protein level gradually decreased in the epididymal epithelium in a spatial manner, specialized within the cytoplasm of clear cells in the cauda part. We detected BPI proteins in intact acrosome, implying its testicular origin; on the other hand, after the acrosome reaction, BPI proteins were observed dispersed across the entire sperm head, especially enriched at the equatorial segment. Our findings suggested a dual origin of the BPI that generated both in the testis and epididymis, and associated with mouse spermatozoa. BPI protein might be involved in the dynamics modification of the sperm plasma membrane and also the fertilization process.

The effect of gas additives on reactive species and bacterial inactivation by a helium plasma jet

In this paper,the influences of gas doping(O2,N2,Air)on the concentrations of reactive species and bactericidal effects induced by a He plasma jet are studied.Firstly,results show that gas doping causes an increase in voltage and a decrease in current compared with the pure He discharge under the same discharge power,which might be attributed to the different chemical characteristics of O2 and N2 and verified by the changes in the gaseous reactive species shown in the optical emission spectroscopy(OES)and Fourier transform infrared(FTIR)spectroscopy.Secondly,the concentrations of aqueous reactive oxygen species(ROS)and reactive nitrogen species(RNS)are tightly related to the addition of O2 and N2 into the working gas.The concentrations of aqueous NO-2 and NO-3 significantly increase while the concentrations of aqueous ROS decrease with the admixture of N2.The addition of O2 has little effect on the concentrations of NO-2 and NO-3 and pH values;however,the addition of O2 increases the concentration of O-2 and deceases the concentrations of H2O2 and OH.Finally,the results of bactericidal experiments demonstrate that the inactivation efficiency of the four types of plasma jets is He+O2>He+Air>He>He+N2,which is in accordance with the changing trend of the concentration of aqueous O.-2 Simultaneously to the better understanding of the formation and removal mechanisms of reactive species in the plasma–liquid interaction,these results also prove the effectiveness of regulating the concentrations of aqueous reactive species and the bacteria inactivation effects by gas doping.