IncP-1 plasmids, first isolated from clinical specimens (R751, RP4), are recognized as important ... more IncP-1 plasmids, first isolated from clinical specimens (R751, RP4), are recognized as important vectors spreading antibiotic resistance genes. The abundance of IncP-1 plasmids in the environment, previously reported, suggested a correlation with anthropogenic pollution. Unexpectedly, qPCR-based detection of IncP-1 plasmids revealed also an increased relative abundance of IncP-1 plasmids in total community DNA from the rhizosphere of lettuce and tomato plants grown in non-polluted soil along with plant age. Here we report the successful isolation of IncP-1 plasmids by exploiting their ability to mobilize plasmid pSM1890. IncP-1 plasmids were captured from the rhizosphere but not from bulk soil, and a high diversity was revealed by sequencing 14 different plasmids that were assigned to IncP-1β, δ, and ε subgroups. Although backbone genes were highly conserved and mobile elements or remnants as Tn501, IS1071, Tn402, or class 1 integron were carried by 13 of the sequenced IncP-1 plasmi...
Journal of Agricultural Chemistry and Biotechnology
The present work aims to surveying plant growth-promoting rhizobacteria (PGPR) for their ability ... more The present work aims to surveying plant growth-promoting rhizobacteria (PGPR) for their ability to produce the plant growth regulator indole-3-acetic acid (IAA). One hundred and forty eight isolates from such bacteria were obtained representing the rhizosphere and rhizoplane of maize, wheat, barley, sorghum and sugar cane form different locations in Egypt (Giza, Faioum, Kafer El-Sheikh and Ismailia). Twenty isolates were selected according to their ability to produce high amount of microbial IAA. The determination of IAA was carried out by calorimetric method and chromatographic analysis (GLC). These isolates were grown on minimal medium with different carbon sources. Glucose was the best carbon source for growing the most isolates and the presence of tryptophan was necessary for production of IAA. Seven isolates which produce IAA more than others were purified and identified applying both conventional morphological, cultural, biochemical methods and API microtube systems. Accordingly, they were placed under the species of Klebsieilla pneumomiae, Azospirillum spp. Enterobacter cloacae, and Pseudomonas fluorescens.
Inoculated and non-inoculated seedlings of maize were grown in fertile clayloam soils of Egypt an... more Inoculated and non-inoculated seedlings of maize were grown in fertile clayloam soils of Egypt and Belgium under subtropical conditions provided in a greenhouse. Acetylene-reducing activity and microbial counts were determined during a period ranging from 6 to 12 weeks after sowing. Irrespective of soil origin, N(2)-fixing spirilla and Azotobacter were common under maize cultivation. Inoculation resulted in a transitional increase in their numbers at early stages of growth. Nitrogenase activity was not detected in the rhizosphere of young plants. The maximum activities measured (81 to 1,436 nmol of C(2)H(4) g h) occurred close to the 50 to 70% silking stage. Inoculation with N(2)-fixing spirilla, particularly in Nile Delta soil, doubled the amount of N(2) fixed in a late period of growth (12 weeks), whereas inoculation with Azotobacter had no noticeable effect.
The recent introduction of plant-only-based culture media enabled cultivation of not-yet-cultured... more The recent introduction of plant-only-based culture media enabled cultivation of not-yet-cultured bacteria that exceed 90% of the plant microbiota communities. Here, we further prove the competence and challenge of such culture media, and further introduce “the inoculum-dependent culturing strategy, IDC”. The strategy depends on direct inoculating plant serial dilutions onto plain water agar plates, allowing bacteria to grow only on the expense of natural nutrients contained in the administered inoculum. Developed colonies are successively transferred/subcultured onto plant-only-based culture media, which contains natural nutrients very much alike to those found in the prepared plant inocula. Because of its simplicity, the method is recommended as a powerful tool in screening programs that require microbial isolation from a large number of diverse plants. Here, the method comfortably and successfully recovered several isolates of endophytic Actinobacteria represented by the six gene...
The rapid development of high-throughput techniques and expansion of bacterial databases have acc... more The rapid development of high-throughput techniques and expansion of bacterial databases have accelerated efforts to bring plant microbiomes into cultivation. We introduced plant-only-based culture media as a successful candidate to mimic the nutritional matrices of plant roots. We herein employed a G3 PhyloChip microarray to meticulously characterize the culturedependent and-independent bacterial communities of the maize root compartments, the endo-and ecto-rhizospheres. An emphasis was placed on the preference of the growth of unculturable candidate divisions/phyla on plant-only-based culture media over standard culture media (nutrient agar). A total of 1,818 different operational taxonomic units (OTUs) were resolved representing 67 bacterial phyla. Plant-only-based culture media displayed particular affinity towards recovering endophytic over ectophytic rhizobacteria. This was shown by the slightly higher recovery of CFUs for endophytes on plant-only-based culture media (26%) than on standard culture media (10%) as well as the higher taxa richness and numbers of exclusive families of unculturable divisions/phyla. Out of 30 bacterial phyla (comprising >95% of the whole population), 13 were of a significantly higher incidence on plant-only-based culture media, 6 phyla of which were not-yet-cultured (Atribacteria, OP9; Dependentiae, TM6; Latescibacteria, WS3; Marinimicrobia, SAR406; Omnitrophica, OP3; BRC1). Furthermore, plant-only-based culture media significantly enriched less abundant and/or hard-to-culture bacterial phyla (Acidobacteria, Gemmatimonadetes, and Tenericutes). These results present conclusive evidence of the ability of plant-only-based culture media to bring the plant-fed in situ microbiome into the status of plant-fed in vitro cultures, and to widen the scope of cultivation of heretofore-unculturable bacterial divisions/phyla.
In order to improve the culturability and biomass production of rhizobacteria, we previously intr... more In order to improve the culturability and biomass production of rhizobacteria, we previously introduced plant-only-based culture media. We herein attempted to widen the scope of plant materials suitable for the preparation of plant-only-based culture media. We chemically analyzed the refuse of turfgrass, cactus, and clover. They were sufficiently rich to support good in vitro growth by rhizobacteria isolates representing Proteobacteria and Firmicutes. They were also adequate and efficient to produce a cell biomass in liquid batch cultures. These culture media were as sufficient as artificial culture media for the cultivation and recovery of the in situ rhizobacteria of barley (Hordeum murinum L.). Based on culture-dependent (CFU plate counting) and culture-independent analyses (qPCR), mowed turfgrass, in particular, supported the highest culturable population of barley endophytes, representing >16% of the total bacterial number quantified with qPCR. This accurately reflected the ...
The plant-based-sea water culture medium is introduced to in vitro cultivation and in situ recove... more The plant-based-sea water culture medium is introduced to in vitro cultivation and in situ recovery of the microbiome of halophytes. The ice plant (Mesembryanthemum crystallinum) was used, in the form of juice and/or dehydrated plant powder packed in teabags, to supplement the natural sea water. The resulting culture medium enjoys the combinations of plant materials as rich source of nutrients and sea water exercising the required salt stress. As such without any supplements, the culture medium was sufficient and efficient to support very good in vitro growth of halotolerant bacteria. It was also capable to recover their in situ culturable populations in the phyllosphere, ecto-rhizosphere and endo-rhizosphere of halophytes prevailing in Lake Mariout, Egypt. When related to the total bacterial numbers measured for Suaeda pruinosa roots by quantitative-PCR, the proposed culture medium increased culturability (15.3-19.5%) compared to the conventional chemically-synthetic culture medium...
Proceedings ISADS 95. Second International Symposium on Autonomous Decentralized Systems, 1995
... Dr. Nadia Hegazi ELECTRONICS RESEARCH INSTITUTE, Tahrir St., Dokki, CAIRO, EGYPT E-MAIL ERI @... more ... Dr. Nadia Hegazi ELECTRONICS RESEARCH INSTITUTE, Tahrir St., Dokki, CAIRO, EGYPT E-MAIL ERI @ FRCU.eun.eg Phone (202)7116831 Abstract To achieve efficient and good performance of logic programs a proposed parallel execution model based on MUSE which ...
Journal of the American Society for Information Science, 1987
... Brief Communication. Information content in textual data: Revisited for Arabic text. Nadia He... more ... Brief Communication. Information content in textual data: Revisited for Arabic text. Nadia Hegazi 1,* ,; Nabil Ali 2 ,; Ehsan Abed 1. Article first published online: 24 MAY 2007. ... Abstract. Arabic as opposed to English is a highly redundant language due to its morphological nature. ...
... Tlie student iiiodel is suppomd bj, a po\\'erful structured Knowledge Base (U) v... more ... Tlie student iiiodel is suppomd bj, a po\\'erful structured Knowledge Base (U) v.hicli contains a large number of facts iind rules of tlic selected domain. The KB contains diagnostic h!potheses \ \ kh are able to explain tlie s.udent belia\,iour. ...
The occurrence of Azotobacter in some Szechoslovakian watercourses has been investigated. Several... more The occurrence of Azotobacter in some Szechoslovakian watercourses has been investigated. Several strains belonging to A. chroococcum and A. beijerinckii were isolated from 7 out of 18 samples. A. insignis has been isolated from the flowing water of Lake Machovo at Doksy. This is first report of this strictly aquatic Azotobacter species in Czechoslovakian watercourses. The taxonomy of the genus Azotobacter was discussed against the background of the existing knowledge resulting mainly from other taxonomic techniques than those based on the phenotypically expressed characters.
IncP-1 plasmids, first isolated from clinical specimens (R751, RP4), are recognized as important ... more IncP-1 plasmids, first isolated from clinical specimens (R751, RP4), are recognized as important vectors spreading antibiotic resistance genes. The abundance of IncP-1 plasmids in the environment, previously reported, suggested a correlation with anthropogenic pollution. Unexpectedly, qPCR-based detection of IncP-1 plasmids revealed also an increased relative abundance of IncP-1 plasmids in total community DNA from the rhizosphere of lettuce and tomato plants grown in non-polluted soil along with plant age. Here we report the successful isolation of IncP-1 plasmids by exploiting their ability to mobilize plasmid pSM1890. IncP-1 plasmids were captured from the rhizosphere but not from bulk soil, and a high diversity was revealed by sequencing 14 different plasmids that were assigned to IncP-1β, δ, and ε subgroups. Although backbone genes were highly conserved and mobile elements or remnants as Tn501, IS1071, Tn402, or class 1 integron were carried by 13 of the sequenced IncP-1 plasmi...
Journal of Agricultural Chemistry and Biotechnology
The present work aims to surveying plant growth-promoting rhizobacteria (PGPR) for their ability ... more The present work aims to surveying plant growth-promoting rhizobacteria (PGPR) for their ability to produce the plant growth regulator indole-3-acetic acid (IAA). One hundred and forty eight isolates from such bacteria were obtained representing the rhizosphere and rhizoplane of maize, wheat, barley, sorghum and sugar cane form different locations in Egypt (Giza, Faioum, Kafer El-Sheikh and Ismailia). Twenty isolates were selected according to their ability to produce high amount of microbial IAA. The determination of IAA was carried out by calorimetric method and chromatographic analysis (GLC). These isolates were grown on minimal medium with different carbon sources. Glucose was the best carbon source for growing the most isolates and the presence of tryptophan was necessary for production of IAA. Seven isolates which produce IAA more than others were purified and identified applying both conventional morphological, cultural, biochemical methods and API microtube systems. Accordingly, they were placed under the species of Klebsieilla pneumomiae, Azospirillum spp. Enterobacter cloacae, and Pseudomonas fluorescens.
Inoculated and non-inoculated seedlings of maize were grown in fertile clayloam soils of Egypt an... more Inoculated and non-inoculated seedlings of maize were grown in fertile clayloam soils of Egypt and Belgium under subtropical conditions provided in a greenhouse. Acetylene-reducing activity and microbial counts were determined during a period ranging from 6 to 12 weeks after sowing. Irrespective of soil origin, N(2)-fixing spirilla and Azotobacter were common under maize cultivation. Inoculation resulted in a transitional increase in their numbers at early stages of growth. Nitrogenase activity was not detected in the rhizosphere of young plants. The maximum activities measured (81 to 1,436 nmol of C(2)H(4) g h) occurred close to the 50 to 70% silking stage. Inoculation with N(2)-fixing spirilla, particularly in Nile Delta soil, doubled the amount of N(2) fixed in a late period of growth (12 weeks), whereas inoculation with Azotobacter had no noticeable effect.
The recent introduction of plant-only-based culture media enabled cultivation of not-yet-cultured... more The recent introduction of plant-only-based culture media enabled cultivation of not-yet-cultured bacteria that exceed 90% of the plant microbiota communities. Here, we further prove the competence and challenge of such culture media, and further introduce “the inoculum-dependent culturing strategy, IDC”. The strategy depends on direct inoculating plant serial dilutions onto plain water agar plates, allowing bacteria to grow only on the expense of natural nutrients contained in the administered inoculum. Developed colonies are successively transferred/subcultured onto plant-only-based culture media, which contains natural nutrients very much alike to those found in the prepared plant inocula. Because of its simplicity, the method is recommended as a powerful tool in screening programs that require microbial isolation from a large number of diverse plants. Here, the method comfortably and successfully recovered several isolates of endophytic Actinobacteria represented by the six gene...
The rapid development of high-throughput techniques and expansion of bacterial databases have acc... more The rapid development of high-throughput techniques and expansion of bacterial databases have accelerated efforts to bring plant microbiomes into cultivation. We introduced plant-only-based culture media as a successful candidate to mimic the nutritional matrices of plant roots. We herein employed a G3 PhyloChip microarray to meticulously characterize the culturedependent and-independent bacterial communities of the maize root compartments, the endo-and ecto-rhizospheres. An emphasis was placed on the preference of the growth of unculturable candidate divisions/phyla on plant-only-based culture media over standard culture media (nutrient agar). A total of 1,818 different operational taxonomic units (OTUs) were resolved representing 67 bacterial phyla. Plant-only-based culture media displayed particular affinity towards recovering endophytic over ectophytic rhizobacteria. This was shown by the slightly higher recovery of CFUs for endophytes on plant-only-based culture media (26%) than on standard culture media (10%) as well as the higher taxa richness and numbers of exclusive families of unculturable divisions/phyla. Out of 30 bacterial phyla (comprising >95% of the whole population), 13 were of a significantly higher incidence on plant-only-based culture media, 6 phyla of which were not-yet-cultured (Atribacteria, OP9; Dependentiae, TM6; Latescibacteria, WS3; Marinimicrobia, SAR406; Omnitrophica, OP3; BRC1). Furthermore, plant-only-based culture media significantly enriched less abundant and/or hard-to-culture bacterial phyla (Acidobacteria, Gemmatimonadetes, and Tenericutes). These results present conclusive evidence of the ability of plant-only-based culture media to bring the plant-fed in situ microbiome into the status of plant-fed in vitro cultures, and to widen the scope of cultivation of heretofore-unculturable bacterial divisions/phyla.
In order to improve the culturability and biomass production of rhizobacteria, we previously intr... more In order to improve the culturability and biomass production of rhizobacteria, we previously introduced plant-only-based culture media. We herein attempted to widen the scope of plant materials suitable for the preparation of plant-only-based culture media. We chemically analyzed the refuse of turfgrass, cactus, and clover. They were sufficiently rich to support good in vitro growth by rhizobacteria isolates representing Proteobacteria and Firmicutes. They were also adequate and efficient to produce a cell biomass in liquid batch cultures. These culture media were as sufficient as artificial culture media for the cultivation and recovery of the in situ rhizobacteria of barley (Hordeum murinum L.). Based on culture-dependent (CFU plate counting) and culture-independent analyses (qPCR), mowed turfgrass, in particular, supported the highest culturable population of barley endophytes, representing >16% of the total bacterial number quantified with qPCR. This accurately reflected the ...
The plant-based-sea water culture medium is introduced to in vitro cultivation and in situ recove... more The plant-based-sea water culture medium is introduced to in vitro cultivation and in situ recovery of the microbiome of halophytes. The ice plant (Mesembryanthemum crystallinum) was used, in the form of juice and/or dehydrated plant powder packed in teabags, to supplement the natural sea water. The resulting culture medium enjoys the combinations of plant materials as rich source of nutrients and sea water exercising the required salt stress. As such without any supplements, the culture medium was sufficient and efficient to support very good in vitro growth of halotolerant bacteria. It was also capable to recover their in situ culturable populations in the phyllosphere, ecto-rhizosphere and endo-rhizosphere of halophytes prevailing in Lake Mariout, Egypt. When related to the total bacterial numbers measured for Suaeda pruinosa roots by quantitative-PCR, the proposed culture medium increased culturability (15.3-19.5%) compared to the conventional chemically-synthetic culture medium...
Proceedings ISADS 95. Second International Symposium on Autonomous Decentralized Systems, 1995
... Dr. Nadia Hegazi ELECTRONICS RESEARCH INSTITUTE, Tahrir St., Dokki, CAIRO, EGYPT E-MAIL ERI @... more ... Dr. Nadia Hegazi ELECTRONICS RESEARCH INSTITUTE, Tahrir St., Dokki, CAIRO, EGYPT E-MAIL ERI @ FRCU.eun.eg Phone (202)7116831 Abstract To achieve efficient and good performance of logic programs a proposed parallel execution model based on MUSE which ...
Journal of the American Society for Information Science, 1987
... Brief Communication. Information content in textual data: Revisited for Arabic text. Nadia He... more ... Brief Communication. Information content in textual data: Revisited for Arabic text. Nadia Hegazi 1,* ,; Nabil Ali 2 ,; Ehsan Abed 1. Article first published online: 24 MAY 2007. ... Abstract. Arabic as opposed to English is a highly redundant language due to its morphological nature. ...
... Tlie student iiiodel is suppomd bj, a po\\'erful structured Knowledge Base (U) v... more ... Tlie student iiiodel is suppomd bj, a po\\'erful structured Knowledge Base (U) v.hicli contains a large number of facts iind rules of tlic selected domain. The KB contains diagnostic h!potheses \ \ kh are able to explain tlie s.udent belia\,iour. ...
The occurrence of Azotobacter in some Szechoslovakian watercourses has been investigated. Several... more The occurrence of Azotobacter in some Szechoslovakian watercourses has been investigated. Several strains belonging to A. chroococcum and A. beijerinckii were isolated from 7 out of 18 samples. A. insignis has been isolated from the flowing water of Lake Machovo at Doksy. This is first report of this strictly aquatic Azotobacter species in Czechoslovakian watercourses. The taxonomy of the genus Azotobacter was discussed against the background of the existing knowledge resulting mainly from other taxonomic techniques than those based on the phenotypically expressed characters.
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