ABSTRACT

The study evaluated the antimicrobial activity of different plants lemon, lime and beetroot extracts against some bacterialenteropathogens, the study focused on the following organisms, Bacillus, Pseudomonas, Shigella and Proteus. The Agar well diffusion method was used in the antimicrobial evaluations. Results from the study showed that the juice extract from lemon inhibited the growth of the test organisms with the inhibitory zones of 6.0mm for Bacillus, 5.0mm for both Pseudomonas and Shigella and 4.0mm for Proteus. It was concluded that extracts from lemon juice inhibited the growth of the tested organisms. It was recommended that further studies should be carried out to confirm the antibacterial activities of these plants.

CHAPTER ONE INTRODUCTION 1.1 BACKGROUND OF STUDY

Plants are rich source of antibacterial agents because they produce wide array of bioactive molecules, most of which probably evolved as chemical defense against predation or infection. Occurrence of bioactive compounds in plants spices/herb extracts is the basis to the antimicrobial effects which at time protects the plant themselves against microorganisms, fungus and viral infectivity (Tagoe et al. 2010). Nowadays natural antimicrobials received a compact awareness from a series of issues related to microorganisms control and as a source of pharmaceutical active compounds (Amrita et al., 2009; Tagoe et al, 2010; Tajkarimi et al., 2010). The use of plant derivatives as antimicrobials has not been extensively addressed until recently since most antibiotics were derived from bacterial or fungal origin. With the increase in resistance and the realization that the effective life span of any antibiotic is limited, new sources especially plant sources are currently being heavily investigated (Abdul et al., 2012).

An antibacterial agent is a substance that kills or inhibitsthe growth of bacteria. Bacteria are becoming resistant to present day antibiotics. The increase in antibiotic resistance bacteria is largely due to the widespread use of antibiotics in medicine in animal care and agriculture (Bansode et al., 2012). Bacteria have the genetic ability to transfer and acquire resistance to drugs, which are utilized as therapeutic agents (Khushwaha et al., 2012). Therefore alternatives to these chemical antibiotics have become necessary. The side effect associated with the available antibiotics is alarming too. Antibacterial properties of plant extract have been a hot topic for the researchers. Besides plants, fruits also have been studied by the researchers for the presence of bioactive compounds close related to her.bs, commonly referred as phytochemicals such as tannins, carotenoids, polyphenols and anthocyanins (Khushwaha et al., 2012). The fruit juices exhibit significant antibacterial effect, the bioactivity being associated with mineral content and biologically active constituents. The term citrus fruit include different types of fruits and products. Although oranges are the major fruit in the citrus fruit group, the group also includes small citrus fruits lemon and lime and grape (Bansode et al., 2012).

Pseudomonas, Bacillus, Salmonella and Klebseila Speciesare of major cause of intestinal and other infections. Previous researchers have demonstrated the antibacterial activity of citrus fruit juices against S. Sonnei and E.coli. (Bansode et al., 2012). In another study it was shown that lime and lemon juice have strong inhibitory activity against Vibrio cholera (Tomotake et al., 2006).

Various citrus fruits have been reported for its antimicrobial effect inclusive both gram negative and gram positive bacteria (Owhe-Ureghe et al., 2010). Lime consist of the nutritional profile of carbohydrates, vitamins, minerals, soluble and insoluble fiber, sugar, sodium, fatty acids, amino acids and others(Jayana et al, 2010); Lemon is a pale yellow, elliptically shaped berry fruit. Citrus fruit in general contain sugar, polysaccharide. organic-acid, lipids, carotenoids, vitamins, minerals, flavonoids, bitter lemonoids and volatile compounds. Lemon is a good source of potassium, calcium & vitamin C. Limon or lime juice have been reported to exhibit antimicrobial activity against Vibrio cholera (Hiroyuki et al. 2OO6). The antimicrobial activity of plants had been received attention many years ago as one of the most effective mechanism for the control of microorganisms (Saadi et al., 2007).Beetroot is a plant that has natural antianemic, antibacterial, anticarcinogenic, antipyretic, antioxidant, antisclerotic, detoxicant and diuretic properties. This medicinal plant has been used as a medicine for 2000 years (Rado’set al., 2013).Compilation of data proves that natural antimicrobials/antioxidants, fruits and vegetables extracts have significant consideration to be used in food as food additives or natural preservative with intention for multidimensional quality (flavour, aroma) and nutritional level enhancement as well antimicrobial property (Belletti et al., 2004; Nanasombat and Lohasupthawee, 2005; Hoque et al., 2007;Corbo et al., 2008; Nkambule, 2008; Amrita et al., 2009; Weerakkody et al., 2010:Das et al., 2011).

1.2 STATEMENT OF THE PROBLEM

In recent years, multiple drug resistance in human pathogenic microorganisms has developed due to indiscriminate use of commercial antimicrobial drugs commonly used in the treatment of infectious diseases. Apart from this, most of the synthetic antimicrobial agents have various adverse effects on human health. On the contrary, the plant-derived antimicrobial agents are not associated with side effects and they have a prospective therapeutic benefit to heal many infectious diseases. Hence, this study is to examine the effects of the extracts from the plants lime, lemon and beetroot on the growth of some pathogens (Pseudomonas, Bacillus, Salmonella and Streptococcus species) and to state its applications in treating diseases caused by these pathogens.

1.3 AIM AND OBJECTIVES OF THE STUDY

The aim of this study is to evaluate the antimicrobial activity of different plants extracts against different bacterial isolates of enteropathogenic origins.The specific objectives were:

1.3.1 To ascertain the antimicrobial sensitivity of these plants extracts on Bacillus species.

1.3.2 To determine the minimum inhibitory concentration of the extract.

1.3.3 To determine the minimum bactericidal concentration of the different plant extract.

1.4   SIGNIFICANCE OF THE STUDY

Bacteria have the genetic ability to transmit and acquire resistance to drugs, which are utilized as therapeutic agents. Finding new naturally active components from plants or plant-based agricultural products has been of interest to many researchers. Hence, a great deal of attraction has been paid to the antibacterial activity of citrus as a potential and promising source of pharmaceutical agents. According to World Health Organization, medicinal plants would be the best source to obtain a variety of drugs. Plants are easily available and cheaper than the conventional drugs, hence its establishment with promising antimicrobial activity is significant.

This study will appraise the antibacterial activity of these plants lime, lemon and beetroot on different pathogens, it will to a wider extend enlighten the public on the use of extracts from lime, lemon and beetroot.

1.5 SCOPE OF THE STUDY

The scope of the study is to evaluate the antibacterial activity of lime, lemon and beetroot extracts against bacterial pathogens (Pseudomonas, Bacillus, Salmonella and Klebsiella species) and to ascertain if the extracts from these plants can be used in the treatment of diseases caused by these bacterial pathogens.

1.6 DEFINITION OF TERMS

Antibacterial: Anything that destroys bacteria or suppresses their growth or their ability to reproduce.

Bacteria: Types of very small organism that lives in air, earth, water, plants and animals, often one which causes a disease.

Microorganisms: These are microscopic organism e.g bacteria, protozoa and viruses.

Minimum inhibitory concentration: This is the lowest concentration of a chemical that prevent the visible growth of bacterium. Other words, it is a bacteriostatic activity.

Minimum bactericidal concentration: Is the concentration that results in microbial death. In other words, the concentration is a bactericidal.

Antimicrobial susceptibility testing: This is a process used in the laboratory to determine which specific antibiotics or agent will be successfully in treating the bacterial infection.

Antibiogram: Antibiogram is the result of antibiotics sensitivity test, it is a laboratory test for the sensitivity of an isolated bacterial strain to different antibiotics.

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