Download (5Mb) - Covenant University Repository

More documents

Recommendations

Info

1134 Actinomyces, Micrococcus and Sarcina, Gram-negative Flavobacterium and yeasts (Hutchinson et al., 1943). This paper reports a negative interaction of P. aeruginosa strains isolated from different aquatic sources against coliforms E. coli and E. aerogenes (Kruse, 1896). Tests were conducted to detect this phenomenon by measuring population of P. aeruginosa and coliform bacteria incubated simultaneously by simulating a recent coliform contamination in an environment where pyocyaninproducing P. aeruginosa strains were already established. MATERIALS AND METHODS Bacterial strains, media and identification methods A total of sixteen aquatic strains of P. aeruginosa were investigated in this study. All strains were isolated from environmental and clinical water samples surrounding Recife, capital of the state of Pernambuco, Brazil and data are shown in Table 1. Representative E. coli EC-5 and E. aerogenes EA-1, respectively, were isolated from distinct well water samples where P. aeruginosa was absent. The reference type strains of P. aeruginosa ATCC 27853, E. coli ATCC 25922 and E. aerogenes ATCC 15012 were also included in the study. All P. aeruginosa strains were identified by using asparagine and acetamide broth at 37±2°C for 24-48h of incubation, fluorescence at 360±20nm wavelength, growth on cetrimide Agar (Acumedia, Maryland, US) and enzymatic oxidase test (Probac do Brasil, São Paulo, Brazil). In order to guarantee conditions favouring the Canadian Journal of Pure and Applied Sciences Table 1. The aquatic sources of Pseudomonas aeruginosa strains. enhancement of pyocyanin, P. aeruginosa strains were grown on Pseudomonas P medium. During the tests, the presence of pyocyanin was verified by the discoloration of acidic KMnO4 solution and by observing fluorescence at 360±20nm (Health Protection Agency, 2003; APHA et al., 1998). E. coli and E. aerogenes strains were identified by using lactose broth and green brilliant bile broth at 37±2°C for 24-48h of incubation, and confirmed in EC broth and eosin-methylene-blue agar, respectively. Biochemical tests: indole production, methyl-red test, Vokes-Proskauer test and citrate utilization, were also performed (APHA et al., 1998). Antibiotic sensitivity was assessed using Müeller-Hinton agar (Merk, Darmstadt, Germany) and antibiotic disks (Sensidisc-DME, São Paulo, Brazil). Characterization of strains inhibitory to coliform The assay was conducted as described by Ichikawa et al. (1971). P. aeruginosa strains were subcultured onto the surface of Müeller-Hinton agar disks and incubated in sterilized Petri dishes at 37±2°C for 48h. Then, coliforms were spread on the surface of Müeller-Hinton agar and disks containing grown P. aeruginosa were transferred onto the agar surface and incubated at 37±1°C overnight. Tests were carried out in triplicate. The inhibition zones formed were measured. A greater inhibition zone diameter indicated more coliform susceptibility to P. aeruginosa. Strains Source Counts (MPN.100ml -1 ) Multi-drug resistance (from 8 antibiotics tested) PA1 Várzea Cemitery (well #1) > 1600 0 PA2 Várzea Cemitery (well #2) 17x10 3 2 PA3 Várzea Cemitery (well #3) > 1600 0 PA4 Tap (hospital) 7x10 3 0 PA5 Bottled water 26x10 3 0 PA6 Storage tank (hospital) 17x10 4 0 PA7 Well (domestic) 11x10 2 PA8 Water cooler (school) ND 0 PA9 Tap (school) ND 0 PA10 Tap (school’s kitchen) ND 0 PA11 Tap (kinder care’s kitchen) ND 0 PA12 Tap (hospital) 23x10 4 0 PA13 Tap (UFPE campus bathroom) ND 0 PA14 Landfill (influent tank) 6x10 5 PA15 Landfill (facultative lagoon) 2x10 4 0 PA16 Well (industry plant) ND 3 ND – not determined. Strain was isolated without quantification 0 3
Inhibitory activity test in liquid-state The three most harmful strains in the selective inhibitory activity assay on solid medium were studied using diluted Müeller-Hinton Broth (Vetec, Rio de Janeiro, Brazil). The assay comprised the P. aeruginosa and coliform enumeration of the Most-Probable-Number for a period of 96h at intervals of 24h by using the multiple tube technique with 5 tubes per dilution: 10.0, 1.0 and 0.1mL. A sample from P. aeruginosa suspension (around 10 2 CFU/mL) was inoculated and incubated at 37±1°C for 72h, after which either EA-1 or EC-5 inoculation occurred by transferring their suspensions (around 10 2 CFU/mL) into the flask and re-incubating overnight. Tests were also conducted between reference type strains. Control tests with each strain grown individually were also carried out using the same conditions and time intervals. RESULTS AND DISCUSSION In this study we investigated the antagonistic interactions among pyocyanin-producing P. aeruginosa strains characterized by in vitro assays on solid and in liquid medium where the coliform bacteria represented a recent contamination in an environment where P. aeruginosa has already been established. All P. aeruginosa strains previously confirmed their ability to produce pyocyanin and further showed antimicrobial activity against coliform bacteria, detected by measuring the inhibition zone diameters formed. Fluorescein production was also observed in five strains. Diameters from 9 to 17±0.1mm for EC-5 and from 7 to Vaconcelos et al. 1135 29±0.1mm for EA-1 (p
Page 2 and 3: EDITOR MZ Khan, SENRA Academic Publ
Page 4 and 5: SENRA Academic Publishers, Burnaby,
Page 6 and 7: Table1. Evolution of glucosamine an
Page 8 and 9: Dunsford, BR., Knabe, DA. and Hacns
Page 12 and 13: 1136 shown in figure 1. Among wild-
Page 14 and 15: 1138 (75/10) and tobramycin (10). T
Page 16 and 17: SENRA Academic Publishers, Burnaby,
Page 18 and 19: Sodium dodecyl sulfate-polyacrylami
Page 20 and 21: 2). RCG1 was purified as a single 1
Page 22 and 23: (100 µg/ml), which showed highest
Page 24 and 25: Rabinovich, GA. and Gruppi, A. 2005
Page 26 and 27: 1152 2009). The main vegetated area
Page 28 and 29: 1154 vehicle disturbs the animals a
Page 30 and 31: 1156 Population and Status of Small
Page 32 and 33: 1158 6.95%, Cape Hare 3.64%, Mouse
Page 34 and 35: 1160 S. No. Scientific name Common
Page 36 and 37: 1162 Grimmett, R., Inskipp, C. and
Page 38 and 39: 1164 housed in clean cages, and pla
Page 40 and 41: 1166 kidneys of all the experimenta
Page 42 and 43: 1168 Prockop, DJ. 1964. Isotopic st
Page 44 and 45: 1170 copper(II) nitrate and zinc(II
Page 46 and 47: 1172 Infrared spectra The relevant
Page 48 and 49: 1174 step was the loss of two molec
Page 50 and 51: 1176 note that though the Mn(II) co
Page 52 and 53: 1178 dimethyl-2H-indazol-6-yl)methy
Page 54 and 55: 1180 prepare the rats feed. The rat
Page 56 and 57: 1182 The result of the mean interna
Page 58 and 59: 1184 Table 8. Histopathology result
Page 60 and 61:
SENRA Academic Publishers, Burnaby,
Page 62 and 63:
RMSE and MBE are statistical instru
Page 64 and 65:
Figure 2 is similar to Figure 1, fo
Page 66 and 67:
dH/dt nT/min (Obs) AE nT (Obs) Dst
Page 68 and 69:
Tables 2 (a-f) contain summaries of
Page 70 and 71:
Pulkkinen, A., Viljanen, A., Pajunp
Page 72 and 73:
1200 that a significant fraction of
Page 74 and 75:
1202 Nino and La Nina periods are a
Page 76 and 77:
1204 periods (1981, 1984, 1991, 199
Page 78 and 79:
1206 Degtyarev, AI, Smirnova, TG. a
Page 80 and 81:
1208 The purpose of the present stu
Page 82 and 83:
1210 Quantitative screening for lip
Page 84 and 85:
1212 A bsorbance 0.70 0.65 0.60 0.5
Page 86 and 87:
1214 Effect of supplementation of C
Page 88 and 89:
1216 surface modification of acryli
Page 90 and 91:
1218 { e1,..., en; en+ 1,..., en+ p
Page 92 and 93:
SENRA Academic Publishers, Burnaby,
Page 94 and 95:
eadings (Q), density (), viscosity
Page 96 and 97:
flow of crude oil and air in horizo
Page 98 and 99:
1128 summarized as ‘By the end of
Page 100 and 101:
1130 Evaluation by EvalAccess 2.0 a
show all

Download (5Mb) - Covenant University Repository

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?