European Academic Research ISSN 2286-4822
ISSN-L 2286-4822
Impact Factor: 3.4546 (UIF)
DRJI Value : 5.9 (B+)
Article Details :
Article Name :
The effect of Cloeme gynandra (‘Rotho’) extract, temperature and pH on attachment and biofilm formation by Escherichia coli 11229, Bacillus cereus ATCC 11778 and Pseudomonas aeruginosa ANCIMB 8295 on stainless steel
Author Name :
Tiroyaone Shimane Tshikantwa; Benau, A. Gashe; Sisai, F. Mpuchane
Publisher :
Bridge Center
Article URL :
Abstract :
An extract of Cloeme gynandra (‘Rotho’), an indigenous leafy vegetable consumed as relish in Botswana, was obtained from sundried leaves of the plant by combining 10g in 100ml of sterile distilled water and filtered using whatman No. 4 paper. Serial dilutions were prepared with Nutrient Broth (NB) (OXOID CM1). Biofilm formation by Escherichia coli 11229, Bacillus cereus ATCC 11778 and Pseudomonas aeruginosa ANCIMB 8295 was investigated by addition of 0.1 ml nutrient broth (NB) of cultures (about 50 cells) into various dilutions of extract on which 2.5cm2 sterile stainless steel coupons were placed. The same procedure was used for pH experiments and pH of the NB was adjusted by adding sterile 0.1M Lactic acid or 0.1M Sodium hydroxide to obtain pH: 4.5, 5.5, 6, 6.92 (control – no acid/base added), 7.5, 8 and 8.5. On the other hand, a similar protocol was used to investigate the effect of temperature on biofilm formation and incubation temperatures of 20oC and 30oC were used. The Cloeme gynandra (‘Rotho’) extract reduced biofilm development for B. cereus but increased it for both E. coli and P. aeruginosa; the period for optimum biofilm formation by Escherichia coli, Pseudomonas aeruginosa, and Bacillus cereus) in NB was two (2) days. Biofilm formed by the same organisms are enhanced by pH levels around neutral (pH 6.92) while acidic and basic extremes reduce attachment. An increase in temperature of incubation was has shown to have a strong positive effect on the development of a biofilm by all the three organisms investigated. However, P. aeruginosa demonstrated more temperature dependence than both E. coli and B. cereus as evidenced in the graphs for results where the highest population of cells recorded was about 600 CFU/ml.
Keywords :
Cloeme gynandra (‘Rotho’); Escherichia coli 11229, Bacillus cereus ATCC 11778 and Pseudomonas aeruginosa ANCIMB 8295; Biofilms; Extract; Stainless steel; Coupon

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