Use Of Bactericides Research Articles

Phytofabrication of Silver Nanoparticles Using Three Flower Extracts and Their Antibacterial Activities Against Pathogen Ralstonia solanacearum Strain YY06 of Bacterial Wilt.

Bacterial wilt caused by the phytopathogen Ralstonia solanacearum (R. solanacearum) is a devastating plant disease worldwide. The use of bactericides and antibiotics for controlling bacterial wilt has shown low efficiency and posed environmental risks. This study was to phytofabricate silver nanoparticles (AgNPs) mediated by canna lily flower (Canna indica L.), Cosmos flower (Cosmos bipinnata Cav.), and Lantana flower (Lantana camara L.). The biosynthesized AgNPs were confirmed and characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscope (TEM), and scanning electron microscopy (SEM). UV-visible spectra showed absorption peak bands at 448, 440, and 428 nm of AgNPs synthesized by C. indica L., C. bipinnata Cav., and L. camara L. flowers, respectively. FTIR spectra confirmed that biofunctional groups of flower extract were involved in the synthesis of AgNPs as capping and stabilizing agents. The spherical AgNPs synthesized by C. indica L., C. bipinnata Cav., and L. camara L. flowers had average diameters of 43.1, 36.1, and 24.5 nm, respectively. The AgNPs (10.0 μg/ml) synthesized by L. camara L. flower had a maximum suppression zone of 18 mm against R. solanacearum strain YY06 compared with AgNPs synthesized by C. indica L. and C. bipinnata Cav. flowers. Bacterial growth, biofilm formation, swimming motility, efflux of nucleic acid, cell death, cell membrane damage, and reactive oxygen species (ROS) generation of R. solanacearum were also negatively affected by AgNPs with high concentration and small size. In summary, the biosynthesized AgNPs can be used as an efficient and environmentally friendly antibacterial agent to reasonably inhibit R. solanacearum.

Screening of Endophytic Bacteria as Biocontrol Agents Against Bacteria Leaf Blight (Xanthomonas oryzae)

Bacterial leaf blight (BLB) is one of major threats in rice production as it can cause 100% yield loss. Concern on the environment and human health has led an attempt to replace existing methods of chemical control and avoid extensive use of bactericides by using endophytic bacteria. The present study was conducted to screen and characterize bacteria isolated from different sources that has potential as antagonistic bacteria against Xanthomonas oryzaepv. oryzae (Xoo), the causal agent of bacterial leaf blight of paddy. Two hundred and thirty-three endophytic bacteria were successfully isolated from roots and leaves from paddy field. Only 17 endophytic bacterial isolates showed positive antagonistic activity indicated by inhibition zone around bacterial colony against Xoo on nutrient agar plate with 2 endophytic isolates (BCA 3 and BCA 12) showed highest inhibitory effect with 35±0.00 mm in diameter. Molecular identification by 16S rRNA amplification successfully identified the antagonistic endophytic bacteria as Pseudomonas fluorescensand Geobacillus thermoparaffinivorans. Findings in this study revealed the biocontrol abilities of isolated endophytes as an excellent option to be used by agriculture sectors to have sustainable environment.

Cationic Organic Nanoaggregates as AIE Luminogens for Wash-Free Imaging of Bacteria and Broad-Spectrum Antimicrobial Application.

The increase in the use of bactericides is a matter of grave concern and a serious threat to human health. The present situation demands rapid and efficient detection and elimination of antibiotic-resistant microbes. Herein, we report the synthesis of a simple C3-symmetric molecular system (TGP) with an intrinsic positive charge through a single-step Schiff base condensation. In a water-dimethyl sulfoxide (DMSO) solvent mixture (80:20 v/v), TGP molecules self-aggregate to form spherical nanoparticles with a positively charged surface that displays efficient fluorescence owing to the aggregation-induced emission (AIE) phenomenon. Both Gram-positive and Gram-negative bacteria could be effectively detected through "turn-off" fluorescence spectroscopy as the electrostatic interaction of the resultant nanoaggregates with the negatively charged bacterial surface induced quenching of fluorescence of the nanoparticles. The fluorescence analysis and steady-state lifetime studies of TGP nanoparticles suggest that a nonradiative decay through photoinduced electron transfer from the nanoparticles to the bacterial surface leads to effective fluorescence quenching. Further, the TGP nanoaggregates demonstrate potent antimicrobial activity against microbes such as multidrug-resistant bacteria and fungi at a concentration as low as 74 μg/mL. A combination of factors including ionic surface characteristics of the nanoparticles for strong electrostatic binding on the bacterial surface followed by possible photoinduced electron transfer from the nanoaggregates to the bacterial membrane and enhanced oxidative stress in the membrane resulting from reactive oxygen species (ROS) generation is found accountable for the high antimicrobial activity of the TGP nanoparticles. The effective disruption of membrane integrity in both Gram-positive and Gram-negative bacteria upon interaction with the nanoaggregates can be observed from field emission scanning electron microscopy (FESEM) studies. The development of simple pathways for the molecular design of multifunctional broad-spectrum antimicrobial systems for rapid and real-time detection, wash-free imaging, and eradication of drug-resistant microbes might be crucial to combat pathogenic agents.

Novel S-Thiazol-2-yl-furan-2-carbothioate Derivatives as Potential T3SS Inhibitors Against Xanthomonas oryzae on Rice.

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv oryzae (Xoo) is considered as the most destructive disease of rice. The use of bactericides is among the most widely used traditional methods to control this destructive disease. The excessive and repeated use of the same bactericides is also becoming the reason behind the development of bactericide resistance. The widely used method for finding the new antimicrobial agents often involves the bacterial virulence factors as a target without affecting bacterial growth. Type III secretion system (T3SS) is a protein appendage and is considered as having essential virulence factors in most Gram-negative bacteria. Due to the conserved construct, T3SS has been regarded as an important mark for the blooming of novel antimicrobial drugs. Toward the search of new T3SS inhibitors, an alternative series of 1,3-thiazole derivatives were designed and synthesized. Their structures were characterized and confirmed by 1H NMR, 13C NMR, MS, and elemental analysis. All the title compounds inhibited the promoter activity of hpa1 gene significantly. Eight of them showed better inhibition than our previous T3SS inhibitor TS006 (o-coumaric acid, OCA). The treatment of Xoo with eight compounds significantly attenuated HR without affecting bacterial growth. The mRNA levels of some representative genes (hrp/hrc genes) were reduced up to different extents. In vivo bioassay results showed that eight T3SS inhibitors could reduce bacterial leaf blight and bacterial leaf streak symptoms on rice, significantly.

Development of a multiplex PCR assay based on the pilA gene sequences to detect different types of Acidovorax citrulli

Bacterial fruit blotch (BFB) of cucurbits, caused by Acidovorax citrulli, is a major threat to commercial watermelon and melon production worldwide. At present, there are at least two genetically distinct sub-populations (group I and II) of A. citrulli that differ in host preference among cucurbit species and copper sensitivity. In this study, we analyzed the pilA gene sequences of 103 A. citrulli strains from China and other countries. Based on these data, we classified all tested A. citrulli strains into three types. The pilA-based type 1 strains in this study coincided with the previously established group I strains; while the type 2 strains coincided with group II strains. Ten strains that did not cluster with group I or II strains were classified into a new type, designated type 3. Based on differences in pilA sequences, we designed a multiplex PCR assay to distinguish the three A. citrulli pilus types. This multiplex PCR assay has proven to be viable for strain typing of 139 A. citrulli strains and for the detection of this pathogen in artificially inoculated seeds and leaves and naturally infected leaves and fruits. This assay proved to be rapid, accurate, reliable and applicable for early distinction of A. citrulli types associated with BFB epidemics. It may also inform the judicious and environmentally sound use of bactericides, especially copper-based compounds.

Corrosion of High Carbon Steel by Bacteria under Aerobic and Anaerobic Conditions

The role of microbes in the corrosion of metals is due to the chemical activities (metabolism) associated with the microbial growth and reproduction. A lot of researches have shown that enormous loss of resources and even lives has been experienced in many countries of the world due to corrosion. There is therefore need to device a means of combating this menace so as to save different countries of the world including Nigeria the cost encured due to corrosion. This research has helped to determine the role of bacteria in the corrosion of high carbon steel under aerobic and anaerobic conditions was investigated using sulphate reducing bacteria and other aerobes. A sample of high carbon steel grade of chemical composition: 96% iron (Fe), 1.08% carbon (C), 0.349% silicon (Si), 0.841% manganese (Mn), 0.005% phosphorus (P) and 0.005% sulphur (S), was obtained in the form of steel plate. Eighteen (18) samples of the high carbon steel were prepared. Standard microbiological methods were used to isolate aerobic and anaerobic bacteria isolates. The microbes isolated from the soil included; aerobes (Bacillus species, Pseudomonas species) and anaerobes (Desulfovibrio species, Thiobacillus species). The role of bacteria in the corrosion of high carbon steel was estimated using the weight loss technique and the electrochemical potential measurement technique. Eighteen samples of a high carbon steel of known compositions were exposed to sulphate reducing bacteria under different environments (aerobic, anaerobic and control). The physical and chemical changes were examined and monitored on weekly basis for six weeks. It was observed that the coupons immersed in the media with sulphate reducing bacterium underwent fast activation and numerous corrosion sites were formed on the surfaces. The average corrosion rate for six weeks (42 days) period of time as determined by the weight loss method and electrochemical testing were found to be 0.0004595 mm/year, -0.712 mV in aerobic environment, 0.0005646 mm/year, -0728 mV in anaerobic environment and 0.0004458 mm/year, -0702 mV in the control or reference environment (distilled water environment). High carbon steel was found to corrode more only in the anaerobic environment. In view of this, high carbon steels were found to be relatively more corrosion resistant than mild and medium carbon steels and may be suitable for application in industries such as the petrochemical industry. Therefore, treating the environment with chlorine but with caution as solutions of chlorine gas in water is corrosive to steels while the use of bactericides or biocides to arrest the action of microbes is important.

Use of Bactericides to Control Acid Mine Drainage from Surface Operations

Use of Bactericides to Control Acid Mine Drainage from Surface Operations

Metabolism of tryptophan in soil

Production of auxins in soil is stimulated by the addition of l-tryptophan ( l-Trp) as a precursor. Metabolism of l-Trp results in the formation of many products including niacin (kynurenine pathway) and serotonin (hydroxylation) in addition to auxins and is regulated by two distinct enzymes, L-TRP-2,3-dioxygenase (TDO) and indole-2,3-dioxygenase (IDO). The roles of IDO and TDO in l-Trp metabolism and indole-3-acetic acid (IAA) formation in soil were studied by the use of bactericides and specific enzyme inhibitors. The addition of a broad spectrum bactericide, chloramphenicol, to soil resulted in a significant decrease of l-Trp catabolism and stimulated hydroxylation of l-Trp. There was no evidence in this work to support the view that l-Trp is transformed through extracellular reactions in soil. Inhibition of TDO by the addition of benzaldehyde and norharman (a potent inhibitor of TDO and IDO) also reduced l-Trp catabolism in soil. Although IAA was detected in all soils treated with bactericides or enzyme inhibitors, production of this secondary metabolite (IAA) was not reduced by blocking the kynurenine pathway or hydroxylation. Auxins were not detected in soils tested with the addition of intermediates of the TDO and IDO pathways (kynurenine and 5-hydroxytryptophan, respectively). Incubation of d-TRP as a possible auxin precursor in California soils resulted in a significant decrease in metabolism compared with l-Trp additions as measured by CO 2 evolution and HPLC analysis. Rhizosphere bacteria isolated from lettuce ( Lactuca sativa) were found to produce more IAA derived from l-Trp after they had been cultured on a medium containing l-alanine, l-asparagine and l-lysine compared with cultures that had been exposed to l-Trp or nutrient agar and then gron on a l-TRP supplemented minimal salts liquid medium. A soil which had extremely low yields of l-TRP-derived IAA increased production of auxin derivatives, including TRP-derived IAA, when incubated for 1 week with the amino acids, l-lysine, l-asparagine and l-alanine. The results suggest that synthesis of IAA in soil may not be the result of direct catabolism of l-Trp but may be linked to the cometabolism of l-Trp by the broad specificity of l-aminotransferases present in soil.

Use of bactericides in emulsion-type lubricating-cooling fluids in service

Use of bactericides in emulsion-type lubricating-cooling fluids in service

Economy in the Use of Drugs

THE first edition of the Medical Research Council's War Memorandum No. 3, entitled "Economy in the Use of Drugs in War-time", was issued in March 1941. It represented the views of the Council's Therapeutic Requirements Committee and a first Supplement to it was issued in November 1941. A second revised edition is now issued (H.M. Stationery Office, 1944. 3d.). It includes an appendix on economy in the use of bactericides and disinfectants, large quantities of which are, the appendix says, used in hospitals and private practice under conditions in which they are not likely to be effective. Sterilization by heat is always preferable to the use of disinfectants and should be used if possible. Mercurial disinfectants have to be imported, and mercury is required for munitions, so that the indigenous coal-tar disinfectants should be used as much as possible. The same Council's War Memorandum No. 6 on "Prevention of 'Hospital Infection' of Wounds" contains recommendations for the use of disinfectants of the phenolic type.

Economy in Use of Bactericides

Economy in Use of Bactericides