The present study was designed to isolate and characterize plant growth promoting rhizobacteria (... more The present study was designed to isolate and characterize plant growth promoting rhizobacteria (PGPR) from different Egyptian salt-affected soils and to evaluate the in vitro bacterial mechanisms related to plant growth promotion and their tolerance for sea water and sodium chloride added in culture media. Two hundred and seven isolates of bacteria and actinobacteria were isolated from salt-affected soils of different Egyptian governorates namely, Kafr El-Shikh (Sakha), El-Qalubia (Meet Kenana), El-Behira (El-Nubaria) and Port Said (Sahl El-Teina). Obtained data showed that the two more potent isolates in nitrogenase activity were identified as Azospirillum lipoferumD178 and Azospirillum lipoferum D207, while the isolates which gave high production of indole acetic acid were identified as Paenibacillus alive D135 and Bacillus pumilus D139, while the isolates which appeared highly inorganic phosphate solubilization were identified as Pseudomonas fluorescence D23 and Bacillus megaterium D159. The six identified strains were taken to examine their tolerance against different concentrations of sodium chloride (1-5%) and different dilutions of sea water (1:2 to 1:10 v/v). All strains under saline stress were able to produce indole acetic acid, gibberellines, catecolate-type siderophores and citric acidtype siderophoresas well as their ability to solubilize inorganic phosphates. All the PGPR activities in the supplemented medium with NaCl or sea water were indicative of their tolerance to the salt. A decrease in activities values has been reported with increasing salt concentration.
An experiment was carried out to examine the effect of carbon source, tryptophan and adenine conc... more An experiment was carried out to examine the effect of carbon source, tryptophan and adenine concentrations on the production of' growth regulators by A. chroococam (R1g) and B.ntegaterhtnr var phosphatictLm (R44). Mannitol and glucose tvere lhe best czu'bort sources for the production of plant gfo\rth regulators (PGRs) by A. chroococcrnt antd B. megaterhutt var. phosphaticzrrr, respectively. A. cltroococctun produced higher amounts ofzeatin and kinetin corrpared to those produced by B. megaterium var. plzosphatictutt whils B. megateriun var. phosphaticarl produced higher amounts of(9Ii) benzyl adenine and (9G) benzyl adenine compared with tlrose pr-odr-rced by .,1. chroococcunr. Production of auxins, gibberellic acid (G&) ard cl.tokinins rvas inct'eased rvith increasir.tg tryptophan concentration. The highest itrnounts of PGRs produced by the tr.vo strains r.rrere obtainecl rviih tryptoplran at I000pN4. Highest amounts of PGI{s pr.oduced by A. clu"aococcunt antl B. ntegateriwtt var. phosphttticum at l0 and 100 pM of adenine, respectively. Also, the produced amounts of gibbereliic acicl and cytokinin lhan that produced by B. megaterium var. pltospl.ntictutt. Genelally, obtained data shorved that thc application of the optiri.ral conditions together gave highest amounts of PGRs as comparecl rvith thc other individLral factors. This result is logic and rvas anlicipated.
This study was carried out to isolate and identity some plant
growth prornoting rhizobactei'ia (P... more This study was carried out to isolate and identity some plant growth prornoting rhizobactei'ia (PGPR) The optimum incubation condition, i.e. temperatrlre turd fermentation peliod. for plant grorvth reguiators (PGRs) production r.vere limitcd. Obtained clata revealed that rhizosphet'e of cereal crops shorved higher PGI'R isolates cornpared to rhizosphere oi'othel crops. Arr-rong the examitred isolates, filiecn rvcre highly ellicient for auxins produclion. The most potent isolates lor indoles production rvele chosen and these isolates rvere identifieil as Azotobacter chroococczln (Rl9) and Bacillus negttteritLnt var. pltosphuticum (R44). The optimurn incubation temperalure for highest pro<luction ofl auxins, gibberellic acid (GA3) and cytokinins \vers 32 and 3OoC ior A, chroococctnt and 13. nrcgaterhnt vt"r. phosphctticarn . respectively. ln addition, the ltighcst prodr-rction oi ihese ph1,'toholmones rvere obtained by the trvo strains after four ancl trvo diiys fbnnentation peliod, respectively.
Salinity is a cr.ucial cglstrailt that slow downs agricr'rlture prodnctior.r in many areas in Egy... more Salinity is a cr.ucial cglstrailt that slow downs agricr'rlture prodnctior.r in many areas in Egypt. Inocr"rlation i,vith plali growth promoting n'ricroorganisnrs ntay enhauce plant grouth urrder salt stress conditious. The obleciive is to evalr-rate the inoculation efJlcieny of biostinrr-rlarit strams (P.setidorrlotla.s f/ttorescence D23, Biciljtrs 1'ttuliltts Dt39 asd Azosltirilluut lipolertunDlTS), hr.rmic acid and olgar.ric lrlantlre (conipost) on growth and yieli of tonato (So/ariunt lycoytersit:tun I-.). This experiment u'as conducted in greerthor"rse condittons at the E,xperimental Farr-n Station o1'Faculty of'Agricutr-Lre Moshtohor dLLring 20 ll. The highest significant increase of dehydrogepase, nitrogenase ancl phosphatase was observed i11 tolrato inocr-rlated with biostinlr.Llant combined rvith hurric acid +'cornpost at one aucl halldose. The highest records of'n-lacrot.tt-Llrierrts r-rptake by tornato shoots rvere observed r.r,hen tomato amenclecl lvrth biostimlLlant conrbined r.vith compost at clil'f'ererit doses + hLrnic acid' Applicatiol o1'hiuric acid cornbineci r,r,ith cornpost significantly dec,reased the proline contcnt in totnato. rvhercas. thc reve;se r,vas observecl i6 nitratc reductase. Dual treatrlcllt of tornato with biostimLrlatit and compost gave higher recorcls of totrato gror'vth charactcristics and yielcl.
the current study was carried out to study the interaction
effect between plant growth promoting ... more the current study was carried out to study the interaction effect between plant growth promoting rhizobacteria (PCPR) and soil-borue pathogenic fungi on grorvth performance of tomato. ITGPRs Azotobttcter chroococcum (Rl9) and Bacillus megaleriutt vu. phosplnticunt (R44) strains used in the current study rvere isolated and identified in previous research by the same authors. Results obtained showed that A. chroococcrLnt and B. megaterium .var. phosphaticttnt gave high suppression against tomato root pathogenic fungi, i.e Fusarium oxysponnl f.sp lycopersici and Fusariutn solani ' In vitro lests, clear zones around PGPR colonies can be attributed to the procluction ol antibiotics-like substances, siderophores and oyanogens by suppressive PCPR strains.
The present study was designed to isolate and characterize plant growth promoting rhizobacteria (... more The present study was designed to isolate and characterize plant growth promoting rhizobacteria (PGPR) from different Egyptian salt-affected soils and to evaluate the in vitro bacterial mechanisms related to plant growth promotion and their tolerance for sea water and sodium chloride added in culture media. Two hundred and seven isolates of bacteria and actinobacteria were isolated from salt-affected soils of different Egyptian governorates namely, Kafr El-Shikh (Sakha), El-Qalubia (Meet Kenana), El-Behira (El-Nubaria) and Port Said (Sahl El-Teina). Obtained data showed that the two more potent isolates in nitrogenase activity were identified as Azospirillum lipoferumD178 and Azospirillum lipoferum D207, while the isolates which gave high production of indole acetic acid were identified as Paenibacillus alive D135 and Bacillus pumilus D139, while the isolates which appeared highly inorganic phosphate solubilization were identified as Pseudomonas fluorescence D23 and Bacillus megaterium D159. The six identified strains were taken to examine their tolerance against different concentrations of sodium chloride (1-5%) and different dilutions of sea water (1:2 to 1:10 v/v). All strains under saline stress were able to produce indole acetic acid, gibberellines, catecolate-type siderophores and citric acidtype siderophoresas well as their ability to solubilize inorganic phosphates. All the PGPR activities in the supplemented medium with NaCl or sea water were indicative of their tolerance to the salt. A decrease in activities values has been reported with increasing salt concentration.
An experiment was carried out to examine the effect of carbon source, tryptophan and adenine conc... more An experiment was carried out to examine the effect of carbon source, tryptophan and adenine concentrations on the production of' growth regulators by A. chroococam (R1g) and B.ntegaterhtnr var phosphatictLm (R44). Mannitol and glucose tvere lhe best czu'bort sources for the production of plant gfo\rth regulators (PGRs) by A. chroococcrnt antd B. megaterhutt var. phosphaticzrrr, respectively. A. cltroococctun produced higher amounts ofzeatin and kinetin corrpared to those produced by B. megaterium var. plzosphatictutt whils B. megateriun var. phosphaticarl produced higher amounts of(9Ii) benzyl adenine and (9G) benzyl adenine compared with tlrose pr-odr-rced by .,1. chroococcunr. Production of auxins, gibberellic acid (G&) ard cl.tokinins rvas inct'eased rvith increasir.tg tryptophan concentration. The highest itrnounts of PGRs produced by the tr.vo strains r.rrere obtainecl rviih tryptoplran at I000pN4. Highest amounts of PGI{s pr.oduced by A. clu"aococcunt antl B. ntegateriwtt var. phosphttticum at l0 and 100 pM of adenine, respectively. Also, the produced amounts of gibbereliic acicl and cytokinin lhan that produced by B. megaterium var. pltospl.ntictutt. Genelally, obtained data shorved that thc application of the optiri.ral conditions together gave highest amounts of PGRs as comparecl rvith thc other individLral factors. This result is logic and rvas anlicipated.
This study was carried out to isolate and identity some plant
growth prornoting rhizobactei'ia (P... more This study was carried out to isolate and identity some plant growth prornoting rhizobactei'ia (PGPR) The optimum incubation condition, i.e. temperatrlre turd fermentation peliod. for plant grorvth reguiators (PGRs) production r.vere limitcd. Obtained clata revealed that rhizosphet'e of cereal crops shorved higher PGI'R isolates cornpared to rhizosphere oi'othel crops. Arr-rong the examitred isolates, filiecn rvcre highly ellicient for auxins produclion. The most potent isolates lor indoles production rvele chosen and these isolates rvere identifieil as Azotobacter chroococczln (Rl9) and Bacillus negttteritLnt var. pltosphuticum (R44). The optimurn incubation temperalure for highest pro<luction ofl auxins, gibberellic acid (GA3) and cytokinins \vers 32 and 3OoC ior A, chroococctnt and 13. nrcgaterhnt vt"r. phosphctticarn . respectively. ln addition, the ltighcst prodr-rction oi ihese ph1,'toholmones rvere obtained by the trvo strains after four ancl trvo diiys fbnnentation peliod, respectively.
Salinity is a cr.ucial cglstrailt that slow downs agricr'rlture prodnctior.r in many areas in Egy... more Salinity is a cr.ucial cglstrailt that slow downs agricr'rlture prodnctior.r in many areas in Egypt. Inocr"rlation i,vith plali growth promoting n'ricroorganisnrs ntay enhauce plant grouth urrder salt stress conditious. The obleciive is to evalr-rate the inoculation efJlcieny of biostinrr-rlarit strams (P.setidorrlotla.s f/ttorescence D23, Biciljtrs 1'ttuliltts Dt39 asd Azosltirilluut lipolertunDlTS), hr.rmic acid and olgar.ric lrlantlre (conipost) on growth and yieli of tonato (So/ariunt lycoytersit:tun I-.). This experiment u'as conducted in greerthor"rse condittons at the E,xperimental Farr-n Station o1'Faculty of'Agricutr-Lre Moshtohor dLLring 20 ll. The highest significant increase of dehydrogepase, nitrogenase ancl phosphatase was observed i11 tolrato inocr-rlated with biostinlr.Llant combined rvith hurric acid +'cornpost at one aucl halldose. The highest records of'n-lacrot.tt-Llrierrts r-rptake by tornato shoots rvere observed r.r,hen tomato amenclecl lvrth biostimlLlant conrbined r.vith compost at clil'f'ererit doses + hLrnic acid' Applicatiol o1'hiuric acid cornbineci r,r,ith cornpost significantly dec,reased the proline contcnt in totnato. rvhercas. thc reve;se r,vas observecl i6 nitratc reductase. Dual treatrlcllt of tornato with biostimLrlatit and compost gave higher recorcls of totrato gror'vth charactcristics and yielcl.
the current study was carried out to study the interaction
effect between plant growth promoting ... more the current study was carried out to study the interaction effect between plant growth promoting rhizobacteria (PCPR) and soil-borue pathogenic fungi on grorvth performance of tomato. ITGPRs Azotobttcter chroococcum (Rl9) and Bacillus megaleriutt vu. phosplnticunt (R44) strains used in the current study rvere isolated and identified in previous research by the same authors. Results obtained showed that A. chroococcrLnt and B. megaterium .var. phosphaticttnt gave high suppression against tomato root pathogenic fungi, i.e Fusarium oxysponnl f.sp lycopersici and Fusariutn solani ' In vitro lests, clear zones around PGPR colonies can be attributed to the procluction ol antibiotics-like substances, siderophores and oyanogens by suppressive PCPR strains.
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Papers by Rasha El-Mehy
production of' growth regulators by A. chroococam (R1g) and
B.ntegaterhtnr var phosphatictLm (R44). Mannitol and glucose tvere lhe
best czu'bort sources for the production of plant gfo\rth regulators (PGRs)
by A. chroococcrnt antd B. megaterhutt var. phosphaticzrrr, respectively.
A. cltroococctun produced higher amounts ofzeatin and kinetin corrpared
to those produced by B. megaterium var. plzosphatictutt whils B.
megateriun var. phosphaticarl produced higher amounts of(9Ii) benzyl
adenine and (9G) benzyl adenine compared with tlrose pr-odr-rced by .,1.
chroococcunr. Production of auxins, gibberellic acid (G&) ard cl.tokinins
rvas inct'eased rvith increasir.tg tryptophan concentration. The highest
itrnounts of PGRs produced by the tr.vo strains r.rrere obtainecl rviih
tryptoplran at I000pN4.
Highest amounts of PGI{s pr.oduced by A. clu"aococcunt antl B.
ntegateriwtt var. phosphttticum at l0 and 100 pM of adenine,
respectively. Also, the produced amounts of gibbereliic acicl and
cytokinin lhan that produced by B. megaterium var. pltospl.ntictutt.
Genelally, obtained data shorved that thc application of the optiri.ral
conditions together gave highest amounts of PGRs as comparecl rvith
thc other individLral factors. This result is logic and rvas anlicipated.
growth prornoting rhizobactei'ia (PGPR) The optimum
incubation condition, i.e. temperatrlre turd fermentation peliod. for
plant grorvth reguiators (PGRs) production r.vere limitcd. Obtained
clata revealed that rhizosphet'e of cereal crops shorved higher PGI'R
isolates cornpared to rhizosphere oi'othel crops. Arr-rong the examitred
isolates, filiecn rvcre highly ellicient for auxins produclion. The most
potent isolates lor indoles production rvele chosen and these isolates
rvere identifieil as Azotobacter chroococczln (Rl9) and Bacillus
negttteritLnt var. pltosphuticum (R44). The optimurn incubation
temperalure for highest pro<luction ofl auxins, gibberellic acid (GA3)
and cytokinins \vers 32 and 3OoC ior A, chroococctnt and 13.
nrcgaterhnt vt"r. phosphctticarn . respectively. ln addition, the ltighcst
prodr-rction oi ihese ph1,'toholmones rvere obtained by the trvo strains
after four ancl trvo diiys fbnnentation peliod, respectively.
i,vith plali growth promoting n'ricroorganisnrs ntay enhauce plant grouth urrder salt stress conditious. The
obleciive is to evalr-rate the inoculation efJlcieny of biostinrr-rlarit strams (P.setidorrlotla.s f/ttorescence D23,
Biciljtrs 1'ttuliltts Dt39 asd Azosltirilluut lipolertunDlTS), hr.rmic acid and olgar.ric lrlantlre (conipost) on growth
and yieli of tonato (So/ariunt lycoytersit:tun I-.). This experiment u'as conducted in greerthor"rse condittons at the
E,xperimental Farr-n Station o1'Faculty of'Agricutr-Lre Moshtohor dLLring 20 ll. The highest significant increase of
dehydrogepase, nitrogenase ancl phosphatase was observed i11 tolrato inocr-rlated with biostinlr.Llant combined
rvith hurric acid +'cornpost at one aucl halldose. The highest records of'n-lacrot.tt-Llrierrts r-rptake by tornato shoots
rvere observed r.r,hen tomato amenclecl lvrth biostimlLlant conrbined r.vith compost at clil'f'ererit doses + hLrnic acid'
Applicatiol o1'hiuric acid cornbineci r,r,ith cornpost significantly dec,reased the proline contcnt in totnato.
rvhercas. thc reve;se r,vas observecl i6 nitratc reductase. Dual treatrlcllt of tornato with biostimLrlatit and compost
gave higher recorcls of totrato gror'vth charactcristics and yielcl.
effect between plant growth promoting rhizobacteria (PCPR) and
soil-borue pathogenic fungi on grorvth performance of tomato. ITGPRs
Azotobttcter chroococcum (Rl9) and Bacillus megaleriutt vu.
phosplnticunt (R44) strains used in the current study rvere isolated
and identified in previous research by the same authors. Results
obtained showed that A. chroococcrLnt and B. megaterium .var.
phosphaticttnt gave high suppression against tomato root pathogenic
fungi, i.e Fusarium oxysponnl f.sp lycopersici and Fusariutn solani '
In vitro lests, clear zones around PGPR colonies can be attributed to
the procluction ol antibiotics-like substances, siderophores and
oyanogens by suppressive PCPR strains.
production of' growth regulators by A. chroococam (R1g) and
B.ntegaterhtnr var phosphatictLm (R44). Mannitol and glucose tvere lhe
best czu'bort sources for the production of plant gfo\rth regulators (PGRs)
by A. chroococcrnt antd B. megaterhutt var. phosphaticzrrr, respectively.
A. cltroococctun produced higher amounts ofzeatin and kinetin corrpared
to those produced by B. megaterium var. plzosphatictutt whils B.
megateriun var. phosphaticarl produced higher amounts of(9Ii) benzyl
adenine and (9G) benzyl adenine compared with tlrose pr-odr-rced by .,1.
chroococcunr. Production of auxins, gibberellic acid (G&) ard cl.tokinins
rvas inct'eased rvith increasir.tg tryptophan concentration. The highest
itrnounts of PGRs produced by the tr.vo strains r.rrere obtainecl rviih
tryptoplran at I000pN4.
Highest amounts of PGI{s pr.oduced by A. clu"aococcunt antl B.
ntegateriwtt var. phosphttticum at l0 and 100 pM of adenine,
respectively. Also, the produced amounts of gibbereliic acicl and
cytokinin lhan that produced by B. megaterium var. pltospl.ntictutt.
Genelally, obtained data shorved that thc application of the optiri.ral
conditions together gave highest amounts of PGRs as comparecl rvith
thc other individLral factors. This result is logic and rvas anlicipated.
growth prornoting rhizobactei'ia (PGPR) The optimum
incubation condition, i.e. temperatrlre turd fermentation peliod. for
plant grorvth reguiators (PGRs) production r.vere limitcd. Obtained
clata revealed that rhizosphet'e of cereal crops shorved higher PGI'R
isolates cornpared to rhizosphere oi'othel crops. Arr-rong the examitred
isolates, filiecn rvcre highly ellicient for auxins produclion. The most
potent isolates lor indoles production rvele chosen and these isolates
rvere identifieil as Azotobacter chroococczln (Rl9) and Bacillus
negttteritLnt var. pltosphuticum (R44). The optimurn incubation
temperalure for highest pro<luction ofl auxins, gibberellic acid (GA3)
and cytokinins \vers 32 and 3OoC ior A, chroococctnt and 13.
nrcgaterhnt vt"r. phosphctticarn . respectively. ln addition, the ltighcst
prodr-rction oi ihese ph1,'toholmones rvere obtained by the trvo strains
after four ancl trvo diiys fbnnentation peliod, respectively.
i,vith plali growth promoting n'ricroorganisnrs ntay enhauce plant grouth urrder salt stress conditious. The
obleciive is to evalr-rate the inoculation efJlcieny of biostinrr-rlarit strams (P.setidorrlotla.s f/ttorescence D23,
Biciljtrs 1'ttuliltts Dt39 asd Azosltirilluut lipolertunDlTS), hr.rmic acid and olgar.ric lrlantlre (conipost) on growth
and yieli of tonato (So/ariunt lycoytersit:tun I-.). This experiment u'as conducted in greerthor"rse condittons at the
E,xperimental Farr-n Station o1'Faculty of'Agricutr-Lre Moshtohor dLLring 20 ll. The highest significant increase of
dehydrogepase, nitrogenase ancl phosphatase was observed i11 tolrato inocr-rlated with biostinlr.Llant combined
rvith hurric acid +'cornpost at one aucl halldose. The highest records of'n-lacrot.tt-Llrierrts r-rptake by tornato shoots
rvere observed r.r,hen tomato amenclecl lvrth biostimlLlant conrbined r.vith compost at clil'f'ererit doses + hLrnic acid'
Applicatiol o1'hiuric acid cornbineci r,r,ith cornpost significantly dec,reased the proline contcnt in totnato.
rvhercas. thc reve;se r,vas observecl i6 nitratc reductase. Dual treatrlcllt of tornato with biostimLrlatit and compost
gave higher recorcls of totrato gror'vth charactcristics and yielcl.
effect between plant growth promoting rhizobacteria (PCPR) and
soil-borue pathogenic fungi on grorvth performance of tomato. ITGPRs
Azotobttcter chroococcum (Rl9) and Bacillus megaleriutt vu.
phosplnticunt (R44) strains used in the current study rvere isolated
and identified in previous research by the same authors. Results
obtained showed that A. chroococcrLnt and B. megaterium .var.
phosphaticttnt gave high suppression against tomato root pathogenic
fungi, i.e Fusarium oxysponnl f.sp lycopersici and Fusariutn solani '
In vitro lests, clear zones around PGPR colonies can be attributed to
the procluction ol antibiotics-like substances, siderophores and
oyanogens by suppressive PCPR strains.