ความหลากหลายทางพันธุกรรมของแบคทีเรียบางกลุ่ม ในพื้นที่โครงการอนุรักษ์พันธุกรรมพืช จังหวัดนครราชสีมา / วิสา ฉิมน้อย = Genetic diversity of some bacteria in the area of plant genetic conservation project in Nakhon Ratchasima province
A study of genetic diversity among soil bacteria was conducted in order to compare samples collected from 4 different areas in Plant Genetic Conservation Project in Nakorn Rachaseema Province. Samples were collected at 4 different times (December 1997, March 1998, June 1998, and September 1998) from 4 grassland areas [grassland checkdam planting (GLDP), grassland control. (GLC), grassland checkdam (GLD), and grassland checkdam planting (GLP)] were collected to compare with the sample from control (C). It was found that the average number of bacterial colony from the above 5 locations was 3.90x10 9, 1.10x10 9, 5.42x10 8, 8.51x10 8, and 2.11x10 9 CFU/g soil, respectively. The average colony number of cellulose-degrading bacteria in those five areas were 5.07x10 2, 1.07x10 3, 1.90x10 3, 3.07x10 3, and 8.65 CFU/g soil, respectively, while those of the actinomycete bacteria in the same areas were 1.25x10 5, 2.97x10 4, 9.88x10 3, 1.53x10 5, and 4.65x10 4 CFU/g soil respectively. The free-living nitrogen-fixing bacteria of the genera Azotobacter, Beijerinkia, and Derzia were found in all 5 locations. Actinomycetes was the group found most and could be isolated into 60 different strains. Thirty isolates were found to have the ability to secrete antibacterial antibiotics on MY agar plates. Twenty-nine isolates (48.33%) could secrete aminoglycoside and sulfonamide antibiotics that inhibited the growth of Bacillus subtilis ATCC11778. Twenty-five isolates (41.67%) could secrete tetracyclines that inhibited Bacillus cereus ATCC6633. Twenty-four isolates (40.00%) could secrete betalactams and sulfonamide that inhibited Micrococcus luteus ATCC9341. Antibiotics secreted from 10 isolates (16.67%) could inhibit the growth of Escherichia coli ATCC1237. And 30 isolates (50.00%) did not inhibit the growth of all four species tested. Observations on characteristics of colony, hypha, and spores were conducted on 10 actinomycete isolates that could produce the most antibiotics (AC2, AC7, AC23, AC39, AC46, AC49, AC50, AC52, AC53 and AC57). It was found that 5 isolates (AC2, AC7, AC23, AC39, AC52) were similar to Streptomyces in colony fluffiness, earthy-smelled, straight hypha, and twisted or curve-ended spore chain. When analyzed for DAP-isomer (diaminopimelic acid-isomer) by thin-layer chromatography, 10 isolates (AC2, AC7, AC23, AC39, AC46, AC49, AC50, AC52, AC53 and AC57). Showed LL-DAP (structural form of diaminopimelic acid was LL). The analysis of 5 isozyme systems: EST ADH MDH PER, and G-6-PD of the strains by Polyacrylamide gel electrophoresis, pattern differences of 3 isozyme systems (EST, ADH, and MDH) were detected.