A search was undertaken for microorganisms that produce an enzyme capable of deacylating glutaryl 7-amino cephalosporanic acid (glutaryl 7-ACA) to 7-ACA. A bacterial strain Hg32, isolated in 8 soil samples from Ha Giang province, exhibited the high intracellular glutaryl 7-ACA acylase activity of 356.6 U/l. Identification of the bacterial strain Hg32 by using biochemical kit API 20 NE for Gram negative bacteria of Bio Merieux's and sequencing the bacterial 16S rDNA (deposited onto GenBank (NCBt) under the accession number HQ677l90.1) revealed that the bacterium was classified as Citrobacter freundii. The strain Hg32 have similar high levels (99 percent) compared with Citrobacter freundii strains JCM 24066 (code: ABS48831.1)
Citrobacter freundii MRB070408-2 (code: GUI26683.1), Citrobacter freundii YRL11 (code: EU373418.1), Ctrobacter freundii SSCT56 (code: AB21 0978.1 ). Characterization of strain showed that bacterium Ctrobacter freundii Hg32 was rod shaped, gram negative, aerobic, nonspore, warm favorite and able to well different carbon sources including: glucose, arabinose, man nose, manitol, N-acetyl glucosamine, maltose, gluconate, malate and citrate. To enhance glutaryl 7-ACA acylase production, optimal cultivation conditions were investigated. This strain Citrobacter freundii Hg32 showed the highest acylase activity toward substrate glutaryl 7-ACA reached up 360 U/l after 30 hours of cultivation in optimized conditions and highest cell density reached up OD 600 nm: 6.23 after 24 hours in the culture fennentation. It grew optimally at temperature of 25 to 35oC and at pH 7.0 to 9.0, but glutaryl 7-ACA acylase activity was the highest when the strain Cifrohacter freundii Hg32 was grown at 30oC and pH 8.0.