Characterization of diazotrophs associated with roots of Leptochloa fusca (L) Kunth

Hasnain Shahida, . and Zafar Fehra, . and Bilal Rakhshanda, . and A. Malik Kausar, . Characterization of diazotrophs associated with roots of Leptochloa fusca (L) Kunth. pp. 17-24. ISSN 0126-6128

A group of nine diazotrophs were isolated from the rhizosphere of kallar grass and cultured on nitrogent-free medium. K5 K8 K9 Kl0 K12 K13 showed high nitrogenase activity ( 18 n mol C2H4 h-l vial)whereas in K7 and K14 it was comparatively low ( 5n mol C2H4 h-1 vial-1). Maximum nitrogenase activity was found in young cultures (after 24 hours of incubation) except for K9 and KJ3 where it was maximum after 36 and 48 h respectively. All strains were Gram-negat produced smooth colonies and pellicles on semi-solid media. Cells of K9 K10 Kl1 K12 and K14 were pleiomorphic: K8 formed long fine rods; K9 was small round or oval shaped; while KM formed beaded rods. Only K8 K13 and K14 were found to be motile. All isolates were able to reduce nitrate and were positive for oxidase an catalese. None of them could denitrify or had urease activity except for KJ4 which was urease positive. K8 K13 and K14 were fermentative and produced red pigments. The isolates K5 K10 and K12 are assigned to the genus Azotobacter while others remained unidentified.

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Abstract

A group of nine diazotrophs were isolated from the rhizosphere of kallar grass and cultured on nitrogent-free medium. K5 K8 K9 Kl0 K12 K13 showed high nitrogenase activity ( 18 n mol C2H4 h-l vial)whereas in K7 and K14 it was comparatively low ( 5n mol C2H4 h-1 vial-1). Maximum nitrogenase activity was found in young cultures (after 24 hours of incubation) except for K9 and KJ3 where it was maximum after 36 and 48 h respectively. All strains were Gram-negat produced smooth colonies and pellicles on semi-solid media. Cells of K9 K10 Kl1 K12 and K14 were pleiomorphic: K8 formed long fine rods; K9 was small round or oval shaped; while KM formed beaded rods. Only K8 K13 and K14 were found to be motile. All isolates were able to reduce nitrate and were positive for oxidase an catalese. None of them could denitrify or had urease activity except for KJ4 which was urease positive. K8 K13 and K14 were fermentative and produced red pigments. The isolates K5 K10 and K12 are assigned to the genus Azotobacter while others remained unidentified.

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Item Type:	Article
AGROVOC Term:	Diazotrophs
AGROVOC Term:	Nitrogenase
AGROVOC Term:	Leptochloa
AGROVOC Term:	Azotobacter
AGROVOC Term:	Nitrogen
AGROVOC Term:	Isolation
AGROVOC Term:	Nitrogen fixing bacteria
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 06:27
URI:	http://webagris.upm.edu.my/id/eprint/22747

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