Medium for isolation and growth of bacteria associated with plum leaf scald and phony peach diseases
J M Wells1, B C Raju, G Nyland
1Southeastern Fruit and Tree Nut Research Laboratory, Science and Education Administration, U. S. Department of Agriculture, Byron, Georgia 31008.
Abstract:
Rickettsia-like bacteria associated with plum leaf scald and phony peach diseases were isolated from diseased but not from healthy tissues and cultured on charcoal-yeast extract medium (BCYE) buffered with ACES (2-[(2-amino-2-oxoethyl) amino]-ethanesulfonic acid). Optimum conditions for isolation and growth on BCYE medium were pH 6.5 to 6.9 at 20 and 25 degrees C under normal atmosphere. Growth of primary colonies and first-passage subcultures was restricted, and colonies reached a maximum diameter of 0.6 mm in 60 days. After 12 passages, subcultures reached maximum growth in 21 days. The rickettsia-like bacteria from BCYE cultures were gram negative, serologically the same as those present in diseased peach and plum, and composed of rod-shaped cells measuring 0.35 by 5 mum (average diameter and maximum length) in a matrix of filamentous strands of similar width but of variable length.
Insights
Researchers isolated Rickettsia-like bacteria from plum leaf scald and phony peach diseases. These bacteria were successfully cultured on specialized charcoal-yeast extract medium (BCYE), optimizing growth conditions.
Area of Science:
- Plant Pathology
- Microbiology
- Bacteriology
Background:
- Plum leaf scald and phony peach are economically significant plant diseases.
- Rickettsia-like bacteria have been implicated as causative agents in these diseases.
- Effective isolation and culture methods are crucial for studying these pathogens.
Purpose of the Study:
- To isolate and culture Rickettsia-like bacteria associated with plum leaf scald and phony peach diseases.
- To determine optimal conditions for the in vitro growth of these bacteria.
- To characterize the morphology and serological properties of the isolated bacteria.
Main Methods:
- Isolation of bacteria from diseased plum and peach tissues.
- Culturing on charcoal-yeast extract medium (BCYE) buffered with ACES.
- Optimization of culture conditions including pH and temperature.
- Microscopic examination and serological testing of cultured bacteria.
Main Results:
- Rickettsia-like bacteria were isolated from diseased tissues only.
- Optimal growth occurred on BCYE medium at pH 6.5–6.9 and 20–25°C.
- Initial cultures showed restricted growth, with colonies reaching 0.6 mm in 60 days.
- After 12 passages, subcultures achieved maximum growth in 21 days.
- Cultured bacteria were gram-negative, rod-shaped, and serologically identical to those in planta.
Conclusions:
- Rickettsia-like bacteria can be successfully isolated and cultured using BCYE medium.
- Established optimal growth conditions facilitate further study of these plant pathogens.
- The characterized bacteria are consistent with the agents causing plum leaf scald and phony peach disease.
