Isolation of Pathogenic Bacteria and Initial Resistance Assay with Detached Fruit Assay Method on Orange Fruits (Citrus sp.)
Rizal Koen Asharo, Nabilah Destiyana, Rahmah Aulia Azzahrah, Noer Syahbani, Riska Azzahra, Imam Safir Alwan Nurza, Reni Indrayanti

Biology Study Program, Universitas Negeri Jakarta

Abstract

Orange fruit (Citrus sp.) is a horticultural crop which is a leading commodity in Indonesia. Pontianak oranges (Citrus nobilis Lour.) and squeezed oranges (Citrus x sinensis) are oranges that have many consumers. Pontianak oranges are widely known and recognized for their distinctive taste, thin skin, and sweet, slightly sour taste. Citrus consumption for households during the 2016-2020 period is projected to increase with an average growth of 2.74% per year. Diseases that attack citrus fruits are caused by bacteria. The purpose of this study was to isolate and identify disease-causing bacteria in orange fruits which were proven by using Koch^s postulates and their morphological characteristics. The method we use is Fruit detach assay with descriptive analysis. The results of the study showed that the isolates obtained from symptomatic citrus fruits were JMPT-1 isolates with a slimy coccus form. JMPT-1 isolate was able to infect citrus fruits with 50% disease severity and 9% infection rate. Orange fruits were positively infected with citrus pathogenic bacteria due to the presence of black spots, brown spots, soft texture, slimy and unpleasant odor similar to the symptoms of the disease like early squeezed oranges.

Keywords: Detached Fruit Assay, disease severity, Koch^s Postulates, orange fruit, pathogenic bacteria

Topic: Biology