Isolation and characterization of bacteria from the skins of guava and apple

Abstract

In recent years, cut fruit products get a warmest hit among current community. A rapid lifestyle changes among most civilizations leads them to choose a convenient way to get balanced meal and nutrients. The control of microbial growth in cut fruits is an important aspect. This study aimed to isolate and characterize the bacteria from apple and guava fruit skins. Moreover, this study also aimed to investigate the effect of temperature and antimicrobial agent in controlling the growth of bacteria from fruit skins. Six bacteria from guava and seven bacteria from apple fruit skins were successfully isolated. These bacteria were then characterized using biochemical tests. Based on Bergey’s manual, the bacteria were classified as Staphylococcus spp., Proteus spp., Micrococcus spp., Bacillus spp., Pseudomonas spp., Erwinia spp. and Enterobacter spp.. Two parameters, which were antimicrobial agent (XY-12) concentration and temperature, were optimized to control the growth of bacteria in the fruit skins. Results revealed that the optimum XY-12 concentration and temperature in retarding the growth of bacteria were 0.6 mL/L and 4°C respectively. A total of 99.4% of bacterial growth reduction was achieved when guava skins were treated with 0.6 mL/L of XY-12 and incubated at 4°C for 4 days in comparison with the control. In addition, a 100% of bacterial growth inhibition was observed when apple skins were treated under the same conditions. The antimicrobial assays (disc diffusion method) were also performed individually on the 13 isolated bacteria. At 0.6 mL/L of XY-12, largest zone of inhibition (2.70 cm) was observed in strain SA 4 after 24 hours of incubation followed by 2.60 cm (strain SG 5) and 2.46 cm (strain SA 2 and SA 3). Negative control (disc with distilled water) did not show any zone of inhibition.