INTRODUCTION 

Koch's postulates are four standards intended to prove a link between the sickness and the pathogenic bacterium. The postulates were developed in 1884 by Friedrich Loeffler and Robert Koch, and Koch published and improved them in 1890. K. Koch's postulates were created as broad principles for determining which infections are isolateable. Scientists that investigate microbial pathogenesis from a molecular perspective have also been impacted by Koch's postulates. Koch's postulate was modified molecularly in the 1980s to help identify the genes in microorganisms that encode virulence factors. A fundamental method for determining if infections are the cause of disease is Koch's postulate. This works just as well for testing for illnesses brought on by fungus or culturable bacteria. The four criteria of Koch's postulates:

1. The organism must be consistently associated with the lesions of the disease.

2. The organism must be isolated from the lesions and grown in pure culture.

3. The organism from pure culture must be re-inoculated into the healthy host and must cause the same disease as was originally observed.

4. The organism must be re-isolated into culture and shown to be identical to the organism originally isolated.

OBJECTIVE

1. To demonstrate Koch's postulate using red chilifruit infected by anthracnose, Trichoderma harzianum spp. 

MATERIALS

PROCEDURE

RESULT

DISCUSSION 

QUESTIONS 

1. Describe obvious physical symptom of anthracnose on red chili fruit. 

= Fruits typically have angular or spherical depressed lesions with concentric rings of acervuli, which are frequently wet. The lesions may clump together when the disease pressure is high. Dark patches on the fruit's surface that are rounded or uneven. As the disease spreads and spores form in the core of the lesion, particularly under damp conditions, affected areas may change from dark brown to black.

2. Observe the time needed by the mycelia of  Tridodorma spp. to reach the petri dish periphery. Which Koch's postulate rule would this represent?

= Koch's postulated rule that this will represent is the second. The organism must be isolated from the lesion and grown in pure culture. By monitoring the growth and behavior in a controlled environment such as a petridish, we can study the characteristics of pathogens independent of other influences, confirming their role in causing disease according to Koch's principle. In addition, we can monitor the growth characteristics of the pathogen in pure culture, such as growth rate, colony morphology, and the ability to cover the petri dish while determining growth patterns parallel to the expected characteristics of Trichoderma spp.

3. Observe the colour of the Tridodorma spp.colony. Are the other colonies have different colour? Explain

= Trichoderma harzianum spp. colonies on chilies are green because to their extensive sporulation. Trichoderma spp. are characterized by their vivid green color. However, certain genes involved in sporulation and pigment production control colony color. The conidium's pigmentation causes Trichoderma harzianum spp. to produce distinctive green spores. This can also be attributed to the environment's dampness, which promotes its quick reproduction. Chili that is not exposed to fungus will not initially be impacted by it.

4. Observe the control chili fruits, did it show symptom like the inoculated fruits? Do you think what you observe is an infectious disease?

= Chilies with green growth and spores are probably infected with fungus. This indicates that it has a fungal infection, just as fruits and vegetables. Fungi typically thrive in ideal environments, including high humidity levels while being stored. Trichoderma harzianum spp. strains utilized in research are a source of fungal growth, which raises the possibility of an infectious disease. An outline of the impacts of environmental variables and the likelihood that infectious diseases could arise under specific circumstances is given by these observations.

5. Were Koch's postulate verified in this laboratary procedure? Explain 

= In my opinion, every procedure performed in the lab complies with Koch's postulate. A set of criteria is used to determine whether a certain infection and disease are related. Tridoderm spp. are being added to both healthy and non-fungus-infected red chilies. The need that the pathogen be isolated from the afflicted host has been met. The fact that chili fruits consistently display Trichoderma harzianum spp. disease symptoms validates this regulation idea. Koch's contagion postulate is supported by the possibility that a pathogen may infect a healthy host and cause the same illness.

CONCLUSION 

REFERENCES 

1. Boundless. (2018, June 20). 10.1D: Koch’s Postulates. Biology LibreTexts. https://bio.libretexts.org/Bookshelves/Microbiology/Microbiology_(Boundless)/10%3A_Epidemiology/10.01%3A_Principles_of_Epidemiology/10.1D%3A__Kochs_Postulates

2. Segre, J. A. (2013). What Does It Take to Satisfy Koch’s Postulates Two Centuries Later?: Microbial Genomics and Propionibacteria acnes. Journal of Investigative Dermatology, 133(9), 2141–2142. https://doi.org/10.1038/jid.2013.260

3. Kiran, R., Akhtar, J., Kumar, P., & Shekhar, M. (2020). Anthracnose of Chilli: Status, Diagnosis, and Management. IntechOpen. doi: 10.5772/intechopen.93614

4. Saxena, A., Raghuwanshi, R., Gupta, V. K., & Singh, H. B. (2016). Chilli Anthracnose: The Epidemiology and Management. Frontiers in Microbiology, 7. https://doi.org/10.3389/fmicb.2016.01527