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Studies on Cellulases and Xylanases of Indigenous Yeast Strains

Thesis Info

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Author

Shariq, Maria

Program

PhD

Institute

University of Karachi

City

Karachi

Province

Sindh

Country

Pakistan

Thesis Completing Year

2018

Thesis Completion Status

Completed

Subject

Microbiology

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/11967/1/Maria%20Shariq_Microbio_2018_UoK_HS%20Diff.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727281889

Similar


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.
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عصر حاضر میں مسلم ریاست کے غیر مسلم ریاستوں سے تعلقات: معاہدات نبوی کے تناظر میں

The Holy Prophet a made several treaties to create a Peaceful state and good neighborly relations with neighboring tribes and Counteries of the Islamic State. He also held peace treaties, which are beneficial to the Muslims in particular and humanity in general. These treaties are effective means of ensuring peace and security and to strengthen the provision of human rights. This study is to highlight the humanitarian dimensions of the treaties of the Prophet to be an invitation aimed at consolidating human values and lay theories of tolerance for coexistence cream among the various nations of the contemporary world, cutting the road on the theories of clash between civilizations to disrupt the harmony and world peace

Development of Integrated Activity Based Mathematics Curriculum at Secondary Level in North West Frontier Province, Pakistan

Mathematics is an important subject and it is the key to advancement in society. Keeping in mind the importance of mathematics in daily life, the present study was designed on the development of an integrated activity based curriculum of mathematics at secondary level in the North West Frontier Province of Pakistan. Recently the name ‘North West Frontier Province’ has been changed officially. The new name is ‘Khyber Pakhtoonkhwa (KPK)’. Therefore hereafter ‘Khyber Pakhtoonkhwa (KPK)’ will be used through out the thesis. The study was aimed; (a) To pinpoint various branches of knowledge which mathematics teachers add/discuss in teaching of mathematics at secondary level through real life integrated activities in applied situation (b) To know up to what extent mathematics teachers use real life integrated activities in applied situation implementing their current secondary level mathematics curriculum (c) To find mathematics teachers’ beliefs about the role and importance of real life integrated activities in mathematics teaching at secondary level (d) To explore mathematics teachers views about various barriers that will prevent or make difficult to use real life integrated activities at secondary level in mathematics teaching (e) To identify what assessment practices mathematics teachers at secondary level use in mathematics teaching and (f) To develop a model of integrated activity based mathematics curriculum at secondary level. This study was carried on in two phases. The population of the study was all secondary level mathematics teachers and students in the province of KPK, Pakistan. In first phase mixed method approach was used. The sample of the study in this phase was selected through multi stage proportionate random sampling method. Total 8 out of 24 vii (33% of the population) districts were included in the sample. Two districts were randomly selected from each cluster (called Zone) already made by KPK public service commission. After selecting districts from each district 1/3 schools each from Urban and rural were randomly selected and then three mathematics teachers from each sample rural school and six mathematics teachers from each sample urban school were chosen randomly for survey. In this way total 681 mathematics teachers 465 from rural and 216 from urban constituted the sample of descriptive part of the study. Also total 32 teachers four from each district two each from urban and rural were included in the sample for interview using purposive sample. While experimental research was carried out using post test only equivalent group experimental design in second phase of the study. Total 60 students of grade 10, 30 for experimental group and 30 for control group of Government Higher Secondary School (GHSS) No.1 Peshawar cant were the sample in second phase of the study. Purposive sampling method was used for school selection and the students were selected through pair random sampling on the basis of the scores they achieved in mathematics in their 9th grade annual examination. In the experiment, use of integrated activity based curriculum units and traditional method of teaching were independent variables while students’ achievement and their retention score were dependent variables. After collection of data, descriptive statistics Percentage, Chi Square Test, Wilcoxon Two Sample Test and Two-independent Sample t-Test were used for analyzing data and drawing conclusion. On the basis of findings the conclusions drawn from first phase of the study were that majority of the teachers didn’t discuss other branches of knowledge in mathematics teaching through real life integrated activities in applied situation, teachers didn’t use real life integrated activities in applied situation using current mathematics curriculum and teachers assessed students through the reproduction of the same questions as given in their textbook. The over all perception of mathematics teachers was positive towards the use of real life integrated activities in applied situation in mathematics teaching. However unavailability of guide book, lack of fund, time constraint, inappropriate training, rote learning based examination system and load of work were considered as barriers in use of integrated activities in mathematics teaching. The conclusion extracted from the second phase was that students’ achievement can be enhanced through the use of real life activities in applied situation in teaching mathematics. Their understanding of using mathematics in real life can be improved, when students are practically involved in the process by using integrated activities in teaching of mathematics.