Comparative bacteriocin activity, growth response to inorganic salts and protein supplementation, fermentation kinetics and structural genes of pediococcus acidilactici isolates / Hamid Ahmadian-Moghadam ; Francisco B. Elegado, chair, advisory committee.

Date

7-2015

Abstract

Bacteriocins are antimicrobial peptides produced by certain bacteria, which can be considered as alternatives to traditional antibiotics. Some strains of Pediococcus acidilactici have been found to produce pediocins and this optimum production for pediocin could be different from the optimum growth temperature, medium component and partial oxygen requirement. There is lack of information on metabolism, fermentation kinetics and bioprocessing strategies for improved yields of bacteriocin producing P. acidilactici strains. The main objective of the study is to measure the differences in bacteriocin activity, bacterial growth characteristics and bacteriocin related pediocin structural gene sequence in different Pediococcus acidilactici strains. Effect of cultural characteristic and bacterial growth correlation of Pediococcus acidilactici in treated with various concentration of organic nutrients (peptone, yeast extract), and inorganic salts (MnSO sub 4.H sub 2 O and K sub 2 HPO sub 4) was measured using spectrophotometry. The effect of different concentration of purified bacteriocin against various indicator organisms and in comparison with commercial antibiotics was measured using agar diffusion assay. The optimum pH, partial oxygen requirement and fermentation coefficients in various P. acidilactici strains using batch fermentation analysis. Also pediocin structural gene (papA) in different P. acidilactici was sequenced and analyzed through bioinformatics analysis. Result was subjected to statistical analysis. Although inorganic salt are essential for bacterial growth, result showed that excessive amount of magnesium sulphate has greater growth suppression than monopotassium phosphate. Results confirmed that bacterial density of P. acidilactici strains in treated with peptone was highest followed by yeast extract and lowest bacterial density was with beef extract treatment. In average, the purified bacteriocin significantly had higher inhibitory potential (2182 au./ml) in comparison with non-purified bacteriocin (1708 au./ml). The inhibitory activity of bacteriocin from P. acidilactici strains, foremost among them strain 3F3, is comparable to Gentamycin (10mg/ml), Kanamycin (50mg./ml and 10mg./ml) and Ampicillin (10mg./ml). The lag phase of batch fermentation was within two (2) hours and then it proceeded to the exponential growth phase up to 8 hours. The decline phase was from 8 to 12 hours and the cells entered into the stationary phase from 12 to 20 hours of fermentation followed by cells lysis. Result showed there is strong negative association in between pH and bacteriocin production (-0.910). Also there is strong positive association in between pH and Optical density. The papA structural gene sequence was shown to be highly conserved, differing only by a single amino acid in this study. The determined peptide sequence contained the highly conserved sequence YGNGV at the N-terminus, a characteristics of class IIa bacteriocins known to have strong antilisterial activity.

Document Type

Dissertation

College

Graduate School (GS)

Adviser/Committee Chair

Francisco B. Elegado

Co-adviser

Evelyn Mae T. Mendoza

Committee Member

Ma. Genaleen Q. Diaz, Jessica F. Simbahan, Antonio C. Laurena, Evelyn Mae T. Mendoza, Francisco B. Elegado

Language

English

LC Subject

Lactic acid bacteria, Lactic acid bacteria, Bacteriocins, Salts, Proteins, Fermentation, aMolecular Biology and Biotechnology Institute of Biological Science

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 996 2015 M5 A36

Notes

Doctor of Philosophy in Molecular Biology and Biotechnology

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