Department of Biotechnology, Veer Narmad South Gujarat University, Udhana-Magdalla Road, Surat, Gujarat *Corresponding Author: drgaurav@vnsgu.ac.in Determination of Antibacterial Activity and MIC of Crude Extract of Abrus precatorius L. Abstract Abrus precatorius L. is the common plant found in the South-Gujarat region. Antibacterial activity from crude Methanolic and Petroleum ether extracts of the legume plant Abrus precatorius (commonly known as Crab's Eye) was carried out. Different parts such as leaves, seeds and roots were taken and extract was prepared to study antibacterial activity on pathogenic as well as opportunistic pathogenic bacteria such as Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi, Salmonella paratyphi A, Salmonella paratyphi B, Escherichia coli and Klebsiella pneumoniae. All the selected organisms were naturally isolated. Antimicrobial activity was determined by the filter paper disc method. Zone of growth inhibition was observed in case of root extract prepared in both Petroleum ether as well as Methanol against Staphylococcus aureus. Further the Minimum Inhibitory Concentration (MIC) was also determined for both the extracts against Staphlococcus aureus and it was found to be 0.44 mg/ml (440 μg/ml) and 0.40 mg/ml (400 μg/ml) for both petroleum ether extract and methanolic extract respectively. Key words: Antibacterial activity; Filter paper disc method; Zone of inhibition; MIC standardization and zone diameter interpretation against a quantitative Minimum Inhibitory Concentration (MIC) value. Materials and Methods The plant materials used in this study were leaves, seeds and roots of Abrus precatorius L. Methanolic and petroleum ether extract were prepared by using Sauxlet apparatus. The solvent was evaporated from plant extract by incubating the extracts in hot air oven at 45ºC until the concentrated extract was obtained. Further like this way the extract were concentrated. The final concentration of the extract is shown in the Table 1. Different organisms like Escherichia coli, Staphylococcus aureus, Salmonella typhi, Salmonella paratyphi A, Salmonella paratyphi B, Pseudomonas aeruginosa, Klebsiella pneumoniae were isolated from natural source. The seven bacterial strains isolated from natural source and were confirmed by biochemical tests Results are shown in Table-2 (Patel, 2008). Antibacterial activity was measured using paper disc method (Qadrie et. al., 2009) [with modification]. The paper disc for the antimicrobial test was prepared by taking aliquotes of 1 ml each of the different extracts in the separate eppendorf tubes. The sterilized paper disc prepared from the Whatman paper (diameter = 5.42 mm) were dipped in the extracts for 1 hr. After incubation, the paper discs were incubated in the oven at 45ºC overnight to evaporate the solvent from the paper disc. For preparing the paper disc for the determination of the minimum inhibitory concentration (MIC), the sterilized paper discs were dipped in each of the different dilutions prepared from the extract from which the antimicrobial activity was observed. Other working steps were same as above. Introduction Various medicinal plants have been used for years in daily life to treat disease all over the world. Moreover, there occurs an enormous diversity in the phytochemicals derived from plants. Different extracts from traditional medicinal plants have been tested to identify the sources of the therapeutics effect (Parekh and Chanda, 2007). As a result some natural products have been approved as new antibacterial drugs. The common name of Abrus precatorius Linn. is Jequerity, crab's eye, Rosary pea. It is medically important plant from Fabaceae family. The plant is native to Indonesia and grows in tropical and subtropical areas of the world where it has been introduced. This plant is found throughout India. It is seen on hedges and bushes in exposed areas. A deciduous, wiry climber with tough branches leaves abruptly pinnate with many pairs of leaflets, the rachis ending in a spine the leaflets oblong rounded at both ends. Fruits are short pods containing hard shiny scarlet and black seeds. Their seeds are often used as beads and in percussion instruments. The seed contains the toxic poison abrin analogous to ricin. The seeds paste is applied locally against skin diseases. Leaves are used as substitutes for licorice (mulethi) considered useful in biliousness and in leucoderma, itching and other skin diseases. Roots used as diuereties. Also used in preparations prescribed for gonorrhea, jaundice and haemoglobinuea bile. Antimicrobial susceptibility testing (AST) is performed by laboratories every day on clinical isolates often with new antimicrobial agents. The techniques employed are often taken for granted and are frequently abused. The use of absorbent paper as a means of carrying antibacterial solutions was first suggested by Pope in 1940 (Heatley, 1944). The Bauer-Kirby method provided important advances in methodological Kalpesh Mistry, Mansi Mehta, Nehal Mendpara, Sharmila Gamit and *Gaurav Shah 25 l Advanced Biotech. Vol. 10 Issue 02 l August 2010 Short Communication