Tarek Moussa

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Levan is an industrially important, functional biopolymer with considerable applications in the food and pharmaceutical fields owing to its safety and biocompatibility. Here, levan-type exopolysaccharide produced by Pantoea agglomerans ZMR7 was purified by cold ethanol precipitation and characterized using TLC, FTIR, 1H, and 13C NMR spectroscopy. The maximum production of levan (28.4 g/l) was achieved when sucrose and ammonium chloride were used as carbon and nitrogen sources, respectively, at 35°C and an initial pH of 8.0. Some biomedical applications of levan like antitumor, antiparasitic, and antioxidant activities were investigated in vitro. The results revealed the ability of levan at different concentrations to decrease the viability of rhabdomyosarcoma and breast cancer cells compared with untreated cancer cells. Levan appeared also to have high antiparasitic activity against the promastigote of Leishmania tropica. Furthermore, levan had strong DPPH radical scavenging (antioxidant) activity. These findings suggest that levan produced by P. agglomerans ZMR7 can serve as a natural biopolymer candidate for the pharmaceutical and medical fields.

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This study aimed to compare the fungal rhizosphere communities of Rhazya stricta, Enneapogon desvauxii, Citrullus colocynthis, Senna italica, and Zygophyllum simplex, and the gut mycobiota of Poekilocerus bufonius (Orthoptera, Pyrgomorphidae, “Usherhopper”). A total of 164,485 fungal reads were observed from the five plant rhizospheres and Usherhopper gut. The highest reads were in S. italica rhizosphere (29,883 reads). Species richness in the P. bufonius gut was the highest among the six samples. Ascomycota was dominant in all samples, with the highest reads in E. desvauxii (26,734 reads) rhizosphere. Sordariomycetes and Dothideomycetes were the dominant classes detected with the highest abundance in C. colocynthis and E. desvauxii rhizospheres. Aspergillus and Ceratobasidium were the most abundant genera in the R. stricta rhizosphere, Fusarium and Penicillium in the E. desvauxii rhizosphere and P. bufonius gut, Ceratobasidium and Myrothecium in the C. colocynthis rhizosphere, Aspergillus and Fusarium in the S. italica rhizosphere, and Cochliobolus in the Z. simplex rhizosphere. Aspergillus terreus was the most abundant species in the R. stricta and S. italica rhizospheres, Fusarium sp. in E. desvauxii rhizosphere, Ceratobasidium sp. in C. colocynthis rhizosphere, Cochliobolus sp. in Z. simplex rhizosphere, and Penicillium sp. in P. bufonius gut. The phylogenetic results revealed the unclassified species were related closely to Ascomycota and the species in E. desvauxii, S. italica and Z. simplex rhizospheres were closely related, where the species in the P. bufonius gut, were closely related to the species in the R. stricta, and C. colocynthis rhizospheres.

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The transcription factors families (TFs) play a critical role in the response regulation of plants to abiotic stresses. The three plant lineages (E. desvauxii, C. colocynthis & Z. simplex) can be separated on the PC1 level, while R. stricta and S. Italica can be distinguished from each other on the PC2 level. A unique 225 transcripts in each of R. stricta and E. desvauxii, 85 transcripts in C. colocynthis, 92 transcripts in S. Italica, and 41 transcripts in Z. simplex were identified. All five plants were shared in only 15 transcripts. Genes had significant gene ontology (GO), R. stricta (450), E. desvauxii (475), C. colocynthis (197), S. Italica (223), and Z. simplex (75) were significantly assigned with GO terms for 29 transcriptional processes. The most abundant TF families in the five plants were MYB followed by, MYB-related, bHLH, and AP2-EREBP (1105, 803, 53 & 472 transcripts, respectively). The zinc TF families were the most transcribed and represented by 8 TF families (PLATZ, C2C2-CO-like, C3H, VOZ, C2C2-GATA, C2C2-DOF, C2H2 & ZF-HD), with the highest one (C3H TF family, 99 transcripts in both R. stricta & Z. simplex). The regulatory network showed that as heat response, 12 genes were upregulated in R. stricta and controlled several genes in some vital processes inside the plant, while E. desvauxii and S. Italica respond to heat by upregulation of 6 genes for each, C. colocynthis by regulation of 3 genes and the least one was Z. simplex by upregulation of two genes only.

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The members of the family of Eentrobacteriaceae harbour a gene cluster called polyketide synthase (pks) island. This cluster is responsible for the synthesis of the genotoxin colibactin that might have an important role in the induction of double-strand DNA breaks, leading to promote human colorectal cancer (CRC). Eleven out of the eighty eight isolates (12.5%) were pks+, distributed as 7 (8%) isolates of E. coli, 2 (2.25%) of K. pneumoniae and 2 (2.25%) of E. aerogenes. The cytotoxic effects of selected pks+ isolates (E. coli and E. aerogenes) on HeLa cells were represented by decreasing cell numbers and enlarged cell nuclei in comparison to the untreated cells. Cytological changes were observed when the infected HeLa cells cultures were stained with AO/EBr and visualized under fluorescent microscope. Some changes that happened in the color of the nuclear chromatin were accompanied by DNA condensation and degradation and fragmentation of nuclei. HeLa cells with green unchanged nuclear chromatin were alive while those with orange-dark and bright red nuclei were dead. It was concluded that a proportion of the Entreobacteriaceae isolates from Iraqi patients was pks+, which exerted cytotoxic effects upon using them to kill HeLa cells. In this study the microscopic observation of the cell morphology reveals the cellular response to the genotoxic insult, with reduced numbers, striking giant cells phenotype (megalocytosis) and fragmentation of nuclei due to the cell cycle arrest and cellular senescence.

افراد العائلة المعوية تمتلك مجموعة من الجينات تدعى Polyketide synthase (pks). هذه المجموعة من الجينات تكون مسؤولة عن تصنيع الذيفان الذي يطلق عليه Colibactin والذي له دور مهم في استحثاث تكسر اشرطة الدنا المزدوجة DNA والذي يؤدي الى استحثاث ورم او ما يعرف بسرطان القولون، احد عشر من اصل ثمانية وثمانين عزلة بكتيرية وتمثل (12.5%) كانت قد توزعت 7(8%) عزلة تعود لبكتربا E. coli، 2(2.25%) عزلة تعود لبكتريا K. pneumonia و 2(2.25%) تعود لبكتريا E. aerogenes كانت حاملة لجينات الكولبكتين قيد الدراسة. تم اختبار لتأثير السمي الخلوي لعزلتين كانت موجبة للجينات قيد الدراسة وهي E. coli and E. aerogenes تجاه خط الخلايا السرطاني المعروف بـ HeLa بينت النائج انخفاض عدد الخلايا وحصول استطالة في انوية الخلايامقارنة بالخلايا الغير معاملة. اظهرت النتائج حصول تغيرات نسيجية في الخلايا بأستخدام صبغة AO/EBr تم ملاحظتها بأستخدام المجهر الفلورسيني: بعض هذه التغيرات تم ملاحظتها في لون كروماتين النواة ومصحوب بتكثف الدنا النووي وكذلك حصول تكسر في النوية، خلايا الـ HeLa التي ظهرت بلون اخضر ولم تحصل فيها اي تغيرات في لون المادة الكروماتينية هي خلايا حية ولم تتم معاملتها مع البكتريا الحاملة للجينات قيد الدراسة، بينما الخلايا المعاملة مع خلايا بكتيرية حاملة للجينات ظهرت انويتها بلون برتقالي داكن وهي خلايا ميتة. يستنتج من ذلك ان عزلات البكتريا المعوية المعزولة من مرضى عراقيين يمكنها ان تفرز مواد سامة (ذيفان الكولبكتين) يمكنها قتل قتل الخلايا السرطانية نوع HeLa وهذا ناتج عن تغيرات حصلت في انوية الخلايا المعرضة للبكتريا وكان واضح في كثافة وتكسر المادة الوراثية للخلايا قيد الدراسة.