حقوق النازحين والمهجرين المدنية في الشريعة الإسلامية والقانون الدولي

الملخص: يهدف البحث إلى بيان مصطلحات النزوح والنازحين والتهجير والمهجرين، وصولاً إلى أحكام النازحين والمهجرين، وانتهاءً بإبراز حقوقهم المدنية، والاجتماعية، والسياسية، والاقتصادية، التي كفلتها الشريعة الإسلامية، والقانون الدولي. إن موضوع أحكام وحقوق النازحين والمهجرين الذي تناولته هذه الدراسة بالمنهج الوصفي التحليلي والمقارن من وجهة نظر شرعية، ومن وجهة نظر قانونية، موضوع واسع يتطرق إلى مناقشة أهم الأحكام المتعلقة بالنازحين والمهجرين، وبيان موقف الشريعة الإسلامية، والقانون الدولي من حقوقهم المقررة شرعاً وقانوناً، إذ أكدت الدراسة على تحريم الشريعة الاسلامية الاعتداء على حق الحياة المكفول للنازحين والمهجرين، وأكدت على حق الحرية لهم، والمساواة، وعدم التمييز، وكذلك القانون الدولي، وكان من أهم النتائج إبراز صلاحية الشريعة الإسلامية لكل الأزمنة والأمكنة، والظروف والحوادث، وشمولها لكل جوانب الحياة، وعمومها لكافة البشر، وتبين أن تعليمات الشريعة الإسلامية، وترسيخها لأحكام النازحين والمهجرين، وإثباتها لحقوقهم جاءت سابقة لما نصت عليه مواد القانون الدولي، وسائر القوانين الوضعية بمئات السنين، وأوصى الباحث المجامع الفقهية، والجهات ذات العلاقة بتبني نشر تعاليم الإسلام، وإبرازه، فهو كفيل بحل جميع مشاكل العالم في هذا الجانب بأحسن الطرق، وأسهلها. الكلمات المفتاحية: النازحين، المهجرين، الشريعة الإسلامية، القانون الدولي، حقوق الإنسان، حفظ النفس، حرية الدين، حرية التغيير.

Studies on Cellulases and Xylanases of Indigenous Yeast Strains

Lignocellulose (LC), a composite of cellulose, hemicellulose and lignin is considered as naturally occurring chemical feedstock. Pakistan being an agricultural country, generates huge amounts of LC substrates in the form of agricultural waste. Global demand for chemicals and insufficient supply of energy in Pakistan, necessitates comprehensive studies on the utilization of LC substrates. LC materials can be used as substrate for the production of plant cell wall degrading enzymes (PCWDEs) including industrially important enzymes, cellulase and xylanase. At present, bacteria and filamentous fungi are employed for the production of cellulases and xylanase on large scale, whereas, very few yeasts have been studied in this regard. Keeping in view the importance of yeast cellulase and xylanase, the present study was conducted on isolation, production and characterization and possible biotechnological application of indigenous yeast strains. The study was initiated with the isolation of yeast strains from environmental samples and retrieval from culture collection available at the Department of Microbiology, University of Karachi. Total 225 yeast strains were subjected to qualitative screening, as well as, quantitative screening for cellulase and xylanase. On the basis of titers of the enzymes, three yeast strains were selected for further studies, MK-157 and MK-160, for endoglucanase (EG) and Xylanase (Xyl) production, repectively, while MK-118 for EG, β-glucosidase (BGL) and Xyl production. The strain, MK-157, was identified on morphological and biochemical basis as Saccharomyces cerevisiae, and was confirmed on molecular basis using ITS primer and species specific primers. Production of EG from S. cerevisiae MK-157 was optimized through shake flask method by adopting one factor at a time (OFAT) strategy. Maximum production of EG from MK-157 was obtained at 30 °C with media pH 7.0 and 1% CMC. EG from MK-157 was characterized and the data revealed that enzyme optimally active at 30 °C under acidic pH in the presence of 1% CMC. The gene encoding EG was isolated, sequenced and submitted to Genbank with accession number MF871644 and KY660547. The strain, MK-160, was identified on morphological, cultural and biochemical basis as Candida tropicalis. The optimized conditions for Xyl production from MK-160 were temperature, 40 °C; pH, 7; and substrate concentration, 0.5%. Optimal activity of Xyl from MK-160 was observed at 40 °C under acidic condition and with 2% of beechwood xylan. Likewise, the strain, MK-118, was identified as C. tropicalison on the basis of morphological, cultural and biochemical tests. MK-118 was studied for coproduction of EG, BGL and Xyl. Production of all the three enzymes from C. tropicalis MK-118 was optimized, separately. Production parameters varied greatly for individual enzyme. Such as for EG and BGL production, cultivation at 40 °C under neutral conditions was maximum while 25 °C with acidic condition was considered as suitable for Xyl production. The highest titers of EG, BGL and Xyl from MK-118 were obtained in presence of 0.5% of CMC, 1.5% of salicin and 1% of xylan, respectively. Moreover, the parameters affect differently when enzyme preparations were characterized. The maximum activity of the EG and BGL was noted at 30 °C while Xyl worked optimally at 40 °C. BGL and Xyl from MK-118 showed maximum active with 1.5% salicin and xylan, respectively, while EG exhibited highest activity with 2% of CMC. Selected yeast strains and their enzymes were also studied for their possible biotechnological application. S. cerevisiae MK-157, C. tropicalis MK-118 and MK-160 were cultivated under submerged fermentation (SmF) of sugarcane bagasse (SB) and wheat bran (WB) and found to produce a multienzyme comprised of EG, BGL and Xyl. Under SSF of SB, the strains MK-157 and MK-118 were cultivated along with a pectinolytic strain, Geotrichum candidum AA-15 that led to significant increase in the production of pectinase. Similarly, the production of multienzyme preparation by the strains MK-118, MK-157 and MK-160 was also studied under solid-state fermentation (SSF) of peels of Citrus limetta (CL). The parameters affecting multienzyme preparation were studied by employing statistical tools, Plackett-Burman Design and Box-Behnken Design. The data inferred that the multienzyme preparation was able to efficiently hydrolyze a variety of pectin-rich and cellulose-rich LC substrates. Moreover, the preparation was also found suitable to be applied for the clarification of orange juice. Ethanol production and dye adsorption ability of strain MK-157 of S. cerevisiae, MK-118 and MK-160 of C. tropicalis were also evaluated. All the three strains produced ~5% of ethanol and absorbed more than 90% of an azo dye, congo red from aqueous solution. Therefore, the strains may appear as suitable candidate for future biotechnological applications.