Assoc.Prof. Panlada Tittabutr

Year	Title	Journal
2006	Identification of two clusters of genes involved in salt tolerance in Sinorhizobium sp. strain BL3 Payakapong W., Tittabutr P., Teaumroong N., Boonkerd N., Singleton P.W., Borthakur D.	Symbiosis
Abstract: Sinorhizobium sp. strain BL3 was isolated from the nodules of Phaseolus lathyroides plants that were found growing under saline conditions in the northeastern region of Thailand. It can tolerate up to 600 mM NaCl and is effective in N2 fixation. A genomic DNA clone library of BL3 was constructed and transferred to the salt-sensitive Rhizobium sp. strain TAL1145 by conjugation and the transconjugants were selected on medium containing 100 mM NaCl. Two hundred colonies that grew under this salt condition were isolated. From twenty-four of those colonies, two clusters of genes involved in salt tolerance were isolated. The deduced proteins encoded by the genes of first region include an ATPase, and a transcriptional regulator of AraC family, while the deduced proteins of the second region showed high similarities with enzymes involved in glycine betaine biosynthesis in Sinorhizobium meliloti. When these gene clusters were transferred to salt-sensitive Rhizobium and Bradyrhizobium, the transconjugants showed increased tolerance to salt stress. ©2006 Balaban. Keyword: Genes; Salt tolerance; Sinorhizobium Scopus Link: https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646503486&partnerID=40&md5=642b217e1d13f2fe73091440831b7214 DOI:
2006	A histidine kinase sensor protein gene is necessary for induction of low pH tolerance in Sinorhizobium sp. strain BL3 Tittabutr P., Payakapong W., Teaumroong N., Boonkerd N., Singleton P.W., Borthakur D.	Antonie van Leeuwenhoek, International Journal of General and Molecular Microbiology
Abstract: The aim of this investigation was to identify and isolate genes involved in acid tolerance from Sinorhizobium sp. strain BL3. It was hypothesized that acid tolerance of strain BL3 could be enhanced by high level expression of certain genes involved in acid tolerance, following insertion of these genes in a multiple copy plasmid. A cosmid clone library of BL3 was introduced into BL3, and the transconjugant colonies were selected at low pH. A single cosmid containing genes for acid tolerance was isolated from 40 different colonies. By transposon-insertion mutagenesis, subcloning and DNA sequencing, a gene involved in acid tolerance, actX, was identified in a 4.4-kb fragment of this cosmid. The actX mutant of BL3 showed increased acid sensitivity and was complemented by the 4.4-kb subcloned fragment. Phaseolus lathyroides seedlings inoculated with recombinant strains containing multiple copies of actX showed increased symbiotic performance at low pH. By constructing an actX::gus fusion, it was shown that actX was induced at low pH. actX encodes a putative histidine kinase sensor protein of a two-component regulatory system. The method of gene identification used in this study for isolation of actX may be applied for the isolation of other genes involved in tolerance to adverse environmental factors. © Springer Science+Business Media, Inc. 2006. Keyword: ActX; Adaptive acid tolerance response; Histidine-kinase; Nodulation; Rhizobium-legume symbiosis; Sinorhizobium Scopus Link: https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646064679&doi=10.1007%2fs10482-005-9015-0&partnerID=40&md5=d31efb6696540f37ae1a4739dce7c928 DOI: 10.1007/s10482-005-9015-0
2005	Cassava as a cheap source of carbon for rhizobial inoculant production using an amylase-producing fungus and a glycerol-producing yeast Tittabutr P., Payakapong W., Teaumroong N., Boonkerd N.	World Journal of Microbiology and Biotechnology
Abstract: The aim of this research was to develop methods to use low-cost carbon compounds for rhizobial inoculant production. Five raw starch materials; steamed cassava, sticky rice, fresh corn, dry corn and sorghum were tested for sugar production by an amylase-producing fungus. Streamed cassava produced the highest amount of reducing sugar after fermentation. Bradyrhizobium japonicum USDA110, Azorhizobium caulinodans IRBG23, Rhizobium phaseoli TAL1383, Sinorhizobium fredii HH103, and Mesorhizobium ciceri USDA2429 were tested on minimal medium supplemented with reducing sugar obtained from cassava fermentation. All strains, except B. japonicum USDA110, could grow in medium containing cassava sugar derived from 100 g steamed cassava per litre, and the growth rates for these strains were similar to those in medium containing 0.5 (w/v) mannitol. The sugar derived from steamed cassava was further used for production of glycerol using yeast. After 1 day of yeast fermentation, the culture containing glycerol and heat-killed yeast cells, was used to formulate media for culturing bradyrhizobia. A formulation medium, FM4, with a glycerol concentration of 0.6 g/l and yeast cells (OD600 = 0.1) supported growth of B. japonicum USDA110 up to 3.61 × 109 c.f.u./ml in 7 days. These results demonstrate that steamed cassava could be used to provide cheap and effective carbon sources for rhizobial inoculant production. © Springer 2005. Keyword: Amylase-producing fungi; Cassava; Glycerol production; Rhizobial inoculant; Rhizobium Scopus Link: https://www.scopus.com/inward/record.uri?eid=2-s2.0-27944466656&doi=10.1007%2fs11274-004-2240-2&partnerID=40&md5=3183e0c6f87d80d2e3b19590a9913849 DOI: 10.1007/s11274-004-2240-2
2004	Regulation of exopolysaccharide synthesis in Rhizobium sp. strain TAL1145 involves an alternative sigma factor gene, rpoH2 Kaufusi P.H., Forsberg L.S., Tittabutr P., Borthakur D.	Microbiology
Abstract: Exopolysaccharide (EPS) produced by Rhizobium sp. strain TAL1145 has been shown to be essential for effective nodulation on Leucaena leucocephala (leucaena). This paper reports the isolation and characterization of an alternative sigma factor gene, rpoH2, involved in the regulation of EPS synthesis in TAL1145. Disruption of this gene in TAL1145 resulted in a Calcofluor-dim mutant RUH102 that produced approximately 18% of the amount of EPS made by TAL1145. This mutation did not affect the normal growth of RUH102 in free-living state. RUH102 induced few nitrogen-fixing nodules, resulting in a significant reduction in total nitrogen content in leucaena. It was complemented for EPS production and nodulation by a 2.0 kb HindIII fragment of TAL1145. Sequence analysis of this fragment revealed the rpoH2 ORF of 870 bp that encoded a protein of 32 kDa. Expression of the rpoH2 ORF in Escherichia coli also revealed a 32 kDa protein. A PCR-constructed clone of 1263 bp, containing the rpoH2 ORF and its upstream putative regulatory region, complemented RUM102 for EPS defects. Comparison of the RpoH2 sequence to proteins in the databases showed significant similarity to RpoH-like sigma factors of other Gram-negative bacteria. By constructing several exo:: Tn3Hogus fusions and transferring them to the backgrounds of TAL1145 and RUH102, it was demonstrated that RpoH2 positively regulates the transcription of some exo genes. © 2004 SGM. Keyword: Scopus Link: https://www.scopus.com/inward/record.uri?eid=2-s2.0-6444227760&doi=10.1099%2fmic.0.27092-0&partnerID=40&md5=41356b299b8bc831788890c5bc7cf1a0 DOI: 10.1099/mic.0.27092-0
2004	Soybean cultivars affect nodulation competition of Bradyrhizobium japonicum strains Payakapong W., Tittabutr P., Teaumroong N., Boonkerd N.	World Journal of Microbiology and Biotechnology
Abstract: The influence of five Thai soybean cultivars on nodulation competitiveness of four Bradyrhizobium japonicum strains was investigated. Cultures of B. japonicum strains THA5, THA6, USDA110 and SEMIA5019 were mixed with each other prior to inoculating germinated soybean seeds growing in Leonard jars with nitrogen-free nutrient solution. At harvest, nodule occupancy by each strain was determined by a fluorescent antibody technique. The term 'general competitive ability' was introduced to describe the average competitive nodule occupancy of a strain in paired co-inoculation with a number of strains on soybean. The nodule occupancies by an individual strain were directly correlated with the proportions of that strain in the inoculum mixtures. USDA110 showed higher nodulation competitiveness than the other strains on three of the five cultivars. The Thai strain THA6 appeared to be more competitive than USDA110 on cultivar SJ5. Thus, nodulation competitiveness of the B. japonicum strains was affected by the cultivars of soybean used. Keyword: Bradyrhizobium; General competitive ability; Interstrain competition; Nodule occupancy; Specific competitive ability Scopus Link: https://www.scopus.com/inward/record.uri?eid=2-s2.0-3442899697&doi=10.1023%2fB%3aWIBI.0000023838.06663.c5&partnerID=40&md5=d6992030db7fb64a8799bf698b3bafe7 DOI: 10.1023/B:WIBI.0000023838.06663.c5
2003	Strain-specific antisera to identify Thai Bradyrhizobium japonicum strains in preserved soybean nodules Payakapong W., Tittabutr P., Boonkerd N.	World Journal of Microbiology and Biotechnology
Abstract: Strain-specific antisera were produced against six Bradyrhizobium japonicum strains using two immunization procedures. These specific antisera were used for detection of bradyrhizobia in preserved soybean nodules. Antisera specific for two of these strains were either conjugated with a fluorescent dye or used with a fluorescent secondary antibody for identification of bradyrhizobia in soybean nodules that were preserved in four different storage conditions. Results show that soybean nodules dried in the oven, stored under room temperature, or at -20°C are as suitable as fresh nodules for strain identification using fluorescent antisera. Keyword: Antisera production; Bradyrhizobium; Soybean nodules Scopus Link: https://www.scopus.com/inward/record.uri?eid=2-s2.0-0347093348&doi=10.1023%2fB%3aWIBI.0000007416.10475.d9&partnerID=40&md5=a4282949965fd895d0f0d69d7a37adbf DOI: 10.1023/B:WIBI.0000007416.10475.d9