Biopreservation of Tomatoes (Solanum Lycopersicum) Using Partially Purified Bacteriocin Produced by Lactobacillus Apis HBAM1 and Lactobacillus Plantarum SJC103
Thesis (M.S.)--Kwara State University (Nigeria), 2021
Includes bibliographical references
Lactic acid bacteria (LAB) are a group of Gram positive, catalase negative and fastidious bacteria that can ferment carbohydrate to produce lactic acid, acetic acid and some can also produce bacteriocin-a ribosomally synthesized antimicrobial peptide. The study aims to characterize and partially purify bacteriocin from Lactobacillus plantarum SJC103 and L. apis HBAm1 and use the partially purified bacteriocin as biopreservative on tomatoes. Fresh samples of goat milk, cow milk, cheese, kunu, nunu and fermented locust beans were obtained from Malete, Kwara state. LABs were isolated under aseptic condition using spread plate method. After biochemical characterization, the isolates obtained were screened for their ability to produce bacteriocin using agar spot and agar well diffusion method. The isolates that produced the widest zone of inhibition were then identified using 16SrRNA gene sequencing analysis. The antibacterial activity of the bacteriocin was tested against Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus. The ability of the isolates to withstand varying temperature, pH and enzymes was determined. Partial purification of the bacteriocin was performed using ammonium sulphate precipitation and the partially purified bacteriocin was used as a biopreservative on tomatoes. A total of thirty-six isolates were obtained in all out of which nine produced bacteriocin, however, two of these isolates produced the widest zone of inhibition and these were later identified as L. plantarum SJC103 and L. apis HBAm1. Bacteriocin from L. Plantarum at 100 0C for 1 hour produced an inhibition zone of 5.50 ± 0.50 mm while for L. apis, 11.00 ± 0.00 mm was obtained at the same temperature. At pH 3, L. apis produced the highest zone of inhibition of 8.00 ± 0.00 mm while L. plantarum produced a zone of inhibition of 4.50 ± 0.50 mm. Treatment with protease produced no inhibitory effect. The biopreservative potential of bacteriocin from both isolates produced a reduction in colony for the treated tomatoes with 1.10 x 107 cfu/g and 2.15 x 107 cfu/g for L. plantarum and L. apis respectively which was significantly reduced when compared with the S. aureus infected tomatoes with 9.25 x 107 cfu/g on day 10 of preservation. It was concluded that bacteriocin from LAB can be harnessed as natural antibacterial in the preservation of fruits such as tomatoes
Electronic reproduction. Ann Arbor, Mich. : ProQuest, 2021
