Isolation of Phytase Producing Bacteria and Study of Phytase as Additive of Fish Feed

Tan, Jin Hao (2022) Isolation of Phytase Producing Bacteria and Study of Phytase as Additive of Fish Feed. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The two main objectives of this project are to isolate phytase from Tilapia fish and soil bacteria, and to determine the effect of phytase additive in fish feed. Phytic acid (phytate), is an anti-nutritional factor that commonly occur in fish meal. Phytate is the main source of phosphorus but they are unusable for most of the aquatic animals due to lack of intestinal phytase. Phytase is a phosphatase that can hydrolyze indigestible phytate to produce free inorganic phosphorus. The source of phytases being used in this project are from soil bacteria and intestinal bacteria of Tilapia fish. The phytase producing bacterial from these sources were obtained by using phytase screening medium. Wheat bran (76.3%) and rice bran extract (79%) were used as the source of phytate to produce phytase screening medium. The presence of phytase producing bacteria will form clear halo zone on the phytase screening medium. Studies done by researcher Nand Kumar Singh, 2013 by using 16S rRNA sequencing showed that the phytase producing soil bacteria might appear to be Bacillus subtilis. Studies done by researcher Argha Khan 2011, showed that fish intestinal bacteria appear to be Rhodococcus sp. and Klebsiella pneumoniae. Studies also show that pH and temperature will affect the phytase production of bacteria. Base on the result done by researcher Xin-zheng Nie 2017, the growth rate, protein efficiency ratio, survival rate and digestible phosphate intake of fish increased as the amount of phytase increased in fish feed. This is because phytic acid contain strong negative charges which enable it to bind with minerals and form very stable complexes, thus causes the loss of minerals to fishes. Phytic acid can also binds to proteins thus reducing the efficiency of protein utilization in fish. Since phytase can hydrolyze phytic acid, the present of phytase will overcome these problems.