Pathogenic Bacteria Isolated From Rust Infected Coffee Leaves Biology Essay

The java plantation is chiefly observed in the Nilgiris, but it besides grows in the Eastern Ghats in Andhra Pradesh. This country has high humidness and temperature and as a consequence of which there is high incidence of rust disease. But when the foliage fragment was aseptically transferred to alimentary agar medium, the bacterium grew and the Fungi did non develop because of its obligatory parasitic nature. Opaque, ash-white, mucoid and rhizoidal settlements with or without xanthous periphery were obtained bespeaking a possible bacterial infection. The bacterium was isolated and sub-cultured for designation and word picture intents.

It was identified as a bacillar, gram negative, aerophilic bacteria giving a positive catalase trial and negative for oxidase, indole production, methyl ruddy, voges proskauer, citrate use and nitrate decrease trials. It besides showed no gas production from lactose. Hence, the being was identified to be Pseudomonas syringae of Pseudomonadaceae household which is the causal being of the foliage blight disease in workss.

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However, the symptoms of Leaf Blight are non observed in the java leaves bespeaking that the pathogen can multiply on the surface of the healthy works and supply inoculant even in the absence of the disease. This is a authoritative illustration of deficiency of quantitative relationship between infective populations and disease incidence.


Coffee is one of the most of import plantation harvest grown largely in South Indian provinces at a tallness between 750-2000 metres above MSL. The java plantation suffers from a figure of diseases of which java rust is one. This disease was foremost reported from Sri Lanka in 1868 and the undermentioned twelvemonth from the province of Karnataka. The rust organism-Hemileia vastatrix, a fungus of the order Uredinales chiefly attacks the foliages and is seldom found on immature roots and fruit. Typically, the disease is recognized by the yellowish-orange powdery lesions or musca volitanss on the bottom of foliages.

Initially, really immature lesions appear as greensick or pale xanthous musca volitanss before monogenesis is apparent. These musca volitanss vary in size and can blend during their development. Since monogenesis of this pathogen occurs through the pore, lesions characterized by the ruptured cuticle of most rusts do non happen, and the lesions are non referred to as pustules. Coffee serves as the obligate host of java rust, that is, the rust must hold entree to and come into physical contact with java ( Coffea arabica ) in order to last. Coffee foliage rust is spread by air current and rain from spores present in the lesions on the bottom of the works. ( Mitchell 1984 )By and large we do see some beings turning singly or in combinations and really frequently they exhibit interaction or hyperparasitism, ensuing in the alteration of the disease rhythm.

While we were seeking to insulate and analyze the rust Fungi from the java leaves we collected from the java plantations in the Eastern Ghats in Andhra Pradesh we obtained a bacterial civilization alternatively of the Fungi. The fungus does non turn in unreal media as it is an obligate parasite. Hence we tried to characterize and analyze the bacteriums obtained from the rust infected java foliages.

Materials and Methods

The bacterial civilization obtained from the Potato Dextrose Agar angles inoculated with the morbid foliage parts was sub cultured in 5 Nutrient Agar angles along with vaccination of a fresh batch of Nutrient Agar angles with the septic foliage after surface sterilisation with 1 % HgCl2.Gram word picture of the bacterium was done. Besides the size was measured. The antibiotic sensitiveness against Streptomycin, Tetracycline, Ampicillin and Linezolid was tested utilizing the phonograph record diffusion method ( Kirby-Bauer, 1960 ) for both fresh civilization and subculture of the bacteriums.For designation and word picture of the bacteriums the standard biochemical trials were performed viz.

Oxidase trial ( W.L. Gaby, C. Hadley, J. Bact. , 74, 365 ( 1957 ) ) , catalase trial, indole production trial, Methyl Red trial ( Michaelis and Marcora, 1912 ) , Voges Proskauer Test ( O. Voges, B.

Proskauer, ( 1898 ) ) , Citrate use trial ( Koser, 1923-24 ) , Nitrate Reduction Test and lactose agitation trial. The consequences were tabulated and being was identified.

Consequences and Discussion

The being was found to be a rod shaped Gram-negative bacteria. Its mean length is about 3 micrometer and comprehensiveness is around 0.5-1 micrometer. It was seen from the antibiotic sensitiveness trial performed with this pathogen that Streptomycin was most effectual against it followed by Tetracycline which showed a smaller zone of suppression ( Refer Table 1 ) .

The being gave a positive Catalase trial and tested negative for Oxidase, Indole production, Methyl Red, Voges Proskauer, Citrate use and Nitrate decrease trials. It showed no gas production from Lactose in the Lactose agitation trial ( Refer Table 2 ) .On the footing of all these biochemical trials the being was identified to be Pseudomonas syringae belonging to the genus Pseudomonas.

Based on 16S rRNA analysis, it has been placed in the P. syringae group. It is a prolific works pathogen which can infect a broad scope of works species, and exists every bit over 50 different pathovars. It is named after the lilac tree ( Syringa vulgaris ) , from which it was foremost isolated. Unlike the other species of Pseudomonass it gives a negative oxidase trial.A peculiar strain of Pseudomonas syringae which usually causes bacterial blight in a broad scope of works species besides infects java workss though non ever ensuing in the disease incidence as seen in this instance. P.

syringae is a nutritionally various being. Although it is a works pathogen, it can besides populate as a saprotroph in the phyllosphere when conditions are non favorable for disease. This pathogen can multiply on the surface of the healthy works and supply inoculant even in the absence of the disease. In the java leaves we got from the Eastern Ghats near Vishakhapatnam symptoms of leaf blight were non seen though the being was found to be shacking in the works therefore demoing a deficiency of quantitative relationship between infective populations and disease incidence.

Some saprotrophic strains of P. syringae have been used as bio control agents against post-harvest putrefactions.


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