Antibacterial effects of Melaleuca leucadendra Ecoenzyme on Pseudomonas aeruginosa
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Introduction: Pseudomonas aeruginosa, a Gram-negative opportunistic pathogen, poses a significant threat in hospital settings, causing nosocomial infections with severe consequences. The bacterium’s high antibiotic resistance, particularly through biofilm formation via quorum sensing (QS), complicates treatment strategies. This study explores the potential of eucalyptus (Melaleuca leucadendra), known for its antimicrobial properties especially due to 1,8-cineole, ecoenzyme in inhibiting Pseudomonas aeruginosa. Materials and Methods: This study is a posttest-only control group design. Pseudomonas aeruginosa bacteria were samped using simple random sampling. The study utilized the agar-well diffusion method on Mueller Hinton agar to assess the antibacterial effect of eucalyptus (Melaleuca leucadendra) ecoenzyme. Concentrations tested ranged from 10% to 100% with three repetitions and incubation at 37 °C for 24 hours. Data were obtained by measuring the inhibition zone using calipers. Results: Contrary to expectations, the study found no antibacterial effect of eucalyptus (Melaleuca leucadendra) ecoenzyme on Pseudomonas aeruginosa at all concentrations tested (100%, 90%, 70%, 60%, 50%, 40%, 30%, 20%, and 10%). Conclusion: The investigation into eucalyptus (Melaleuca leucadendra) ecoenzyme revealed no discernible antibacterial activity against Pseudomonas aeruginosa. These findings challenge the initial hypothesis and underscore the importance of thorough experimentation in assessing the potential of natural agents for combating nosocomial infections. Further research is needed to elucidate the complex interactions between Pseudomonas aeruginosa and eucalyputs (Melaleuca leucadendra).This paper presented the influence of Al(III) on biodegradability, micromorphology, composition and functional groups characteristics of the biofilm extracellular polymeric substances (EPS) during different growth phases. The sequencing batch biofilm reactors were developed to cultivate biofilms under different Al(III) dosages. The results elucidated that Al(III) affected biofilm development adversely at the beginning of biofilm growth, but promoted the biofilm mass and improved the biofilm activity with the growth of the biofilm. The micromorphological observation indicated that Al(III) led to a reduction of the filaments and promotion of the EPS secretion in growth phases of the biofilm, also Al(III) could promote microorganisms to form larger colonies for mature biofilm. Then, the analysis of EPS contents and components suggested that Al(III) could increase the protein (PN) of tightly bound EPS (TB-EPS) which alleviated the metal toxicity inhibition on the biofilm during the initial phases of biofilm growth. The biofilm could gradually adapt to the inhibition caused by Al(III) at the biofilm maturation moment. Finally, through the Fourier transform infrared spectroscopy, it was found that Al(III) was beneficial for the proliferation and secretion of TB-EPS functional groups, especially the functional groups of protein and polysaccharides.
Extracellular polymeric substance
Bacterial growth
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Pseudomonas infection
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Cross‐reactions between Pseudomonas aeruginosa and 36 other bacterial species were studied by various quantitative immunoelectrophoretic techniques. A complex Pseudomonas aeruginosa antigen and a corresponding rabbit antiserum were used as a reference system. Ten of the 55 Pseudomonas aeruginosa antigens were cross‐reactive with antigens from as many as 33 other bacterial species, gram‐negative as well as gram‐positive. As judged by absorption of antibodies the degree of cross‐reactivity of each of the 10 Pseudomonas aeruginosa antigens with antigens from other species was found to be 25–100%, depending on the species and the antigen in question. The closest antigenic relationship to Pseudomonas aeruginosa was found in 5 other Pseudomonas species, but members of the Enterobacteriaceae also cross‐reacted fairly extensively with Pseudomonas aeruginosa . One of the cross‐reactive antigens reacted with a normally occurring antibody in sera from rabbits.
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Biofilms are surface-associated communities of microorganisms embedded within self-secreted extracellular polymeric substances, and a major cause of chronic and persistent infections. Respiratory Pseudomona aeruginosa infection is the leading reason for morbidity and mortality in cystic fibrosis patients. The formation of biofilms by P. aeruginosa in the airway is thought to increase persistence and antibiotic resistance during infection. Biofilm formation of P. aeruginosa is regulated by complicated signaling systems including quorum sensing and two-component systems that control the synthesis of extracellular polymeric substances. Furthermore, iron is an essential and scarce nutrient for bacteria and an important signal factor. P. aeruginosa has developed multiple iron uptake systems to sequester enough iron for its survival, with important regulatory roles in both release of virulence factors and formation of biofilms. In this review, we summarize recent advances in biofilm formation and its regulation along with the iron-uptake strategies in P. aeruginosa, to provide new insights and understanding to fight bacterial biofilms.生物被膜是单细胞微生物通过其分泌的胞外多聚基质粘附于介质表面并将其自身包绕其中而成的膜样微生物细胞聚集物。生物被膜的形成使细菌具有更强的适应外界环境的能力，也是导致微生物产生耐药性及慢性感染性疾病难以治疗的重要原因之一。铜绿假单胞菌在肺部的定殖是肺囊性纤维化病患者发病和死亡主要原因，其造成的感染通常与形成抗生素抗性极强的生物被膜有关。铜绿假单胞菌生物被膜的形成受控于多种复杂的细菌调控体系之下，包括群体感应系统及参与调节胞外多聚基质合成的双组分调控系统等。此外，为了利用低浓度的环境铁来维持生存并完成各种生理功能，铜绿假单胞菌进化出了一系列铁摄取系统，这些系统对其毒力因子的释放和生物被膜的形成又起着重要的调控作用。本文主要对铜绿假单胞菌生物被膜的形成与调控机制及其铁摄取系统进行了综述，为进一步了解及清除铜绿假单胞菌引发的问题提供途径与思路。.
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Objective To conduct real-time observation of living biofilm formation and determine the thickness of the Pseudomonas aeruginosa biofilm.Methods After green fluorescent protein(GFP)expression plasmid was transfected to Pseudomonas aeruginosa,the horizontal section scanning of living biofilm was done in real-time with confocal laser scanning microscope(CLSM).The thickness of living biofilm was determined according to Z axial distance.Results The biofilm formation of Pseudomonas aeruginosa was observed in three stages,which were the adherence phase from 0 to 6 hours,the assembly phase from 6 to 24 hours,and the maturation phase from 24 to 72 hours.The thickness of the biofilm at 6,24,48,and 72 hr were 6.1±2.8,29.2±2.3,61.4±1.4,and 61.8±1.1μm,respectively.Statistical analysis showed that the thickness of the biofilm at 6 hr was less than that of at 24 hr(P0.01)and the thickness of the biofilm at 24 hr was less than that of at 48 hr(P0.01).There was no difference in the thickness of the biofilm between the time of 48 hr and 72 hr(P0.05).Conclusion CLSM can be used to observe the biofilm formation of Pseudomonas aeruginosa in real-time and to determine its thickness.
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Introduction. Bacterial cell hydrophobicity and adherence to a substrate are one of the most important factors in biofilm formation. Group A streptococcus is an unstable and low biofilm productor. Importance of biofilm production in streptococcal pathogenesis is still unknown. Objective. The aim of this study was to determine the impact of hydrophobicity and adherence on the biofilm production of group A streptococcal invasive and noninvasive isolates, and also to evaluate the stability of biofilm production in time function. Methods. Adherence, hydrophobicity and biofilm production were investigated in a total of 172 isolates divided into three groups: noninvasive, low invasive and highly invasive. Adherence to uncoated and laminin-coated microtiter plates and biofilm production after 12, 24 and 48 hours of incubation was determined using the method described by Stepanovic et al. Hydrophobicity was measured using the MATH test by Rosenberg and SAT test by Lindhal. Results. Correlation between adherence and biofilm production was detected in the group of noninvasive isolates. These isolates were stable biofilm productors during all three time periods of biofilm production. In the groups of invasive and noninvasive isolates no statistical correlation was detected among the analysed variables. The invasive isolates were unstable biofilm productors. Conclusion. Noninvasive isolates were stable biofilm producers; as detected, they showed a direct correlation between adherence and biofilm production, and a negative impact of hydrophobicity on the biofilm production. Invasive isolates were unstable biofilm productors; it was observed that there was no correlation between adherence and hydrophobicity with biofilm production.
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Homoserine
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Results of minimal inhibitory concentration tests with a diversity of bacterial strains showed that 9-chloro-9-(4-diethylaminophenyl)-10-phenylacridan (C-390) inhibited the growth of all microorganisms tested (other than Pseudomonas aeruginosa) at 25 microgram/ml or less, whereas MICs obtained for P. aeruginosa ranged from to to greater than 100 microgram/ml. Therefore, C-390 was evaluated as a potential selective agent for P. aeruginosa in pseudomonas agar F. Recovery tests were conducted on this medium with 53 strains o P. aeruginosa, and the results were compared to those obtained in similar tests on commercially available selective media, i.e., pseudomonas isolation agar and Pseudosel agar. The results of these comparisons indicated that pseudomonas agar F with C-390 was significantly less inhibitory than Pseudosel agar and pseudomonas isolation agar and more selective than pseudomonas isolation agar. The incorporation of C-390 in pseudomonas agar F also provided a medium that was both selective and differential. Preliminary evidence also suggested that C-390 may be added to other basal media with comparable results.
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