Isolation and Identification of L-Methioninase Producing Bacteria from Sugarcane Plantation Soil

Goh, Jia Zhang (2018) Isolation and Identification of L-Methioninase Producing Bacteria from Sugarcane Plantation Soil. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

L-Methioninase-producing bacteria are commonly found in soil from sugarcane field or paddy field, as reported by some researchers. This enzyme garnered attention due to its possible benefits in the cancer therapy because cancer cells depend on methionine in order to proliferate. Therefore, starving them of it might arrest them in the late S-G2 phase causing apoptosis to occur. This enzyme is also responsible for the production of methanthiol which is associated with flavor in high quality Cheddar cheese. Methanthiol is formed when the L-Methioninase cleaved L-Methionine into products such as ketobutyrate, methanthiol and ammonia. The objective of this research was to isolate and identify the soil bacteria that produced the enzyme L-Methioninase. Results from the isolated soil bacteria showed positive bacteria colonies using the rapid-plate assay method and L-Methioninase assay. Positive isolates were stained reddish pink in color when cultured on the modified M9 medium due to the changes in pH caused by ammonia. The increase in absorbance from the L-Methioninase assay proved the presence of the L-Methioninase. From the culture of 4 different soil samples from the sugarcane field, only one was identified as a positive isolate. Glycine was shown to be a better inhibitor of L-Methioninase compared to EDTA. Characterization tests such as gram staining, spore staining, motility test and catalase test were done and it was found that the bacteria was filamentous, gram positive and catalase positive. DNA of the isolate was extracted and amplified then later sequenced. Based on the results, the results might be a Streptomyces pseudovenezuelae strain NN90.