In vitro assessment of microbial isolates from soil rhizosphere of a rehabilitated forest

Nik M. Majid, . and Franklin R. Kundat, . and O. H. Ahmed, . and Wong S. King, . (2011) In vitro assessment of microbial isolates from soil rhizosphere of a rehabilitated forest. [Proceedings Paper]

A total of 134 microbial isolates were recovered from the soil and tree roots of a rehabilitated forest at Bintulu Sarawak Malaysia. Bacteria dominated the microbial population 60.4 followed by fungi 39.6. Saprophytic fungi such as Aspergillus and Rhizopus were the most dominant fungi isolated 56. Fusarium species isolated include a variety of Fusarium species 42 and Trichoderma spp 2. This shows that bacteria are the most common microbes compared to fungi in the soil and tree roots of the rehabilitated forest. Dual Culture Test is an established method used to distinguish isolates with antagonistic potential from large populations. Preliminary screening conducted was a quick screening procedure to select potential antagonistic bacterial isolates towards Fusarium. Isolates with positive results inhibition zone in the preliminary screening were retested to obtain their degree of inhibition PIRG values by conducting the dual culture test. From the total bacterial isolates tested only 30 showed antagonistic activity towards Fusarium the pathogen that causes Fusarium root rot. The remaining 70 did not show any antagonistic potential PIRG values 0. Eighty eight percent of the potential bacteria isolates were weak inhibitors of PIRG values less than 50. Only 21 of the isolates showed strong inhibition to Fusarium with PIRG values between 50-70. The bacterial isolates selected in the subsequent tests were RFEB25 RFEB54 and RFEB62 with PIRG values of 62 for 69 and 73 respectively. The mechanisms of antagonism of the selected bacterial and fungal isolates were further established in the double plate and poison-food tests. Results from both tests revealed that RFEB25 RFEB54 and RFEB62 inhibited the growth of Fusarium by producing both volatile and non-volatile metabolites. The strongest inhibition by volatile inhibitory substances was produced by RFEB62 PIRG value 36 while RFEB25 PIRG value 21 was least effective. Results from the in vitro antagonism tests Dual Culture Double Plate and Poison-Food Test showed that most of the isolates recovered from the soil and tree roots of the rehabilitated forest were antagonistic to Fusarium highlighting potential development as BCAs against Fusarium root rot disease.

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Abstract

A total of 134 microbial isolates were recovered from the soil and tree roots of a rehabilitated forest at Bintulu Sarawak Malaysia. Bacteria dominated the microbial population 60.4 followed by fungi 39.6. Saprophytic fungi such as Aspergillus and Rhizopus were the most dominant fungi isolated 56. Fusarium species isolated include a variety of Fusarium species 42 and Trichoderma spp 2. This shows that bacteria are the most common microbes compared to fungi in the soil and tree roots of the rehabilitated forest. Dual Culture Test is an established method used to distinguish isolates with antagonistic potential from large populations. Preliminary screening conducted was a quick screening procedure to select potential antagonistic bacterial isolates towards Fusarium. Isolates with positive results inhibition zone in the preliminary screening were retested to obtain their degree of inhibition PIRG values by conducting the dual culture test. From the total bacterial isolates tested only 30 showed antagonistic activity towards Fusarium the pathogen that causes Fusarium root rot. The remaining 70 did not show any antagonistic potential PIRG values 0. Eighty eight percent of the potential bacteria isolates were weak inhibitors of PIRG values less than 50. Only 21 of the isolates showed strong inhibition to Fusarium with PIRG values between 50-70. The bacterial isolates selected in the subsequent tests were RFEB25 RFEB54 and RFEB62 with PIRG values of 62 for 69 and 73 respectively. The mechanisms of antagonism of the selected bacterial and fungal isolates were further established in the double plate and poison-food tests. Results from both tests revealed that RFEB25 RFEB54 and RFEB62 inhibited the growth of Fusarium by producing both volatile and non-volatile metabolites. The strongest inhibition by volatile inhibitory substances was produced by RFEB62 PIRG value 36 while RFEB25 PIRG value 21 was least effective. Results from the in vitro antagonism tests Dual Culture Double Plate and Poison-Food Test showed that most of the isolates recovered from the soil and tree roots of the rehabilitated forest were antagonistic to Fusarium highlighting potential development as BCAs against Fusarium root rot disease.

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Item Type:	Proceedings Paper
Additional Information:	3 ref. QH 541.5 R27 I61 2011
AGROVOC Term:	Forest rehabilitation
AGROVOC Term:	Microbes
AGROVOC Term:	Fusarium
AGROVOC Term:	Biological control
AGROVOC Term:	Rhizosphere
AGROVOC Term:	Malaysia
Geographical Term:	MALAYSIA
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 05:14
URI:	http://webagris.upm.edu.my/id/eprint/11599

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