الفهرس 
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Abstract
It is well known that the use of compost in agricultural production is associated with many benefits. These benefits include physical improvement of the soil and improvement of its biological and chemical status. The composting process is primarily concerned with the creation of a suitable environment in which aerobic microorganisms which are responsible for the breakdown of organic matter can be optimally active.
The aim of this study is to isolate and identify thermo-cellulolytic bacteria from different sources to be used as a bioaccelerator in the composting process, for shortening the composting period without deterioration of compost quality. In addition to this step, PGPB was added to the compost as a carrier. At the end of the study and the best treatment was used to fertilize of wheat.
For this purpose, a series of laboratory and pot experiments were designed and carried out. Obtained results can be summarized as follows:
5.1. Isolation, screening and identification of cellulases producing thermophilic bacteria
5.1.1. Isolation of cellulases producing thermophilic bacteria
This work was focused on the isolation, screening and identification of some potent thermophilic cellulase producers. Accordingly, samples were collected from different sources rich in cellulose such as compost, soil and manure.
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One hundred and seventeen isolates of thermophilic bacteria were isolated on CMC agar medium which contains CMC as a sole carbon source. Forty five isolates from one hundred and seventeen were able to be cellulase producers while the other was noncellulase producers.
The percentages of the cellulase and noncellulase producing thermophilic bacteria, the obtained results emphasized that the cellulase producing isolates were 45 represented which 38.5%; whereas the noncellulase 7 isolates producered represent 61.5%. 13 isolates were isolated from compost, seven isolates from soil and twenty five were isolated from manure.
The highest records of cellulolytic thermophilic isolates were obtained from manure samples with 56% followed by compost with 29%. The lowest percentage was found to be in soil samples with 15% from the total number of bacterial isolates.
5.2. Primary Screening of cellulose decomposers isolates
All isolates were able to grow on CMC agar medium. Judging from the ratio between the clearing zone diameter and colony diameter where only eleven isolates were chosen for enzyme production studies
5.3. Secondary screening of cellulose decomposers isolates
In this experiment the most potent eleven isolates of cellulose decomposers were secondary screened for cellulase activity using carboxymethylcellulose activity (CMC-ase) and filter paper activity (Fp-ase)
The isolates number C27 and C30 were the highest producers of cellulases (CMC-ase), filter-paperase (FP-ase); whereas data show that
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the isolate number S55 is the lowest producer of celluases. Moreover, isolate number M 88 gave high activity of CMC-ase but still less than isolates number C27 and C30 in Fp-ase activity.
Correlation coefficient for the most potent isolates.
Correlation coefficient between celluolysis diameter and CMC-ase
the correlation between celluolysis diameter and carboxymethyl cellulase is positive and quite strong for isolate number C27 while it is less strong concerning isolate C30.
- Correlation coefficient between celluolysis diameter and Fp-ase
The correlation between celluolysis diameter and Fp-ase is positive in both isolates. In spite of this, the correlation is quite strong for the isolate number C27 while it is less strong in the isolate number C30.
Correlation coefficient between CMC-ase and Fp-ase
The correlation coefficient between carboxymethyl cellulase (CMC-ase) and filter paper (FP-ase) is positive and strong for both isolates of bacteria.
5.4. Screening for xylanase producing thermophilic bacteria
This screening was carried out to investigate the ability of the thermophilic cellulolytic isolates to produce xylanase using the growth diameter and clear zone of hydrolysis. Ten isolates which gave high records in cellulose decomposition were used in this experiment. The six isolates from ten isolates gave positive results, which achievement 60%, while the rest 40% isolates gave negative results. The obtained results clearly show that isolates number 27 and 30 gave the highest growth diameter clear zone of xylan hydrolysis.
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The isolates numbers (C27 and C30) were the highest producers for cllulases and xylanases enzymes. Therefore those two isolates were selected and identified to be used as bioaccelerator in composting.
5.5. Identification of the more potent cellulases and xylanses producers.
Obtained results showed that, isolate (C27) is aerobic, spore former (central endospores), Gram positive, acid fastness, motile and rod-shaped bacterium. The second isolate (C30) is aerobic, nonspore former, Gram positive, acid fastness, motile and irregular shaped bacterium. It is clear that the two isolates (C27 and C30) have all the morphological and biochemical characteristics of Bacillus circulans and Cellulomonas flavigena, were identified as Bacillus circulans (C27) and Cellulomonas flavigena (C30) by Biology system.
5.6. Antagonistic between the two selected strains
The antagonistic action between Bacillus circulans and Cellulomonas flavigena was found to be negative using the dual culture experiment. This test was true because the two isolates grew together in the same Petri dish, which is an evident of the commensalism in the compost pile.
5.7. Compost preparation
This experiment was carried out at Qalubia governorate (EL-Gabal EL-Asfar) during the summer season of 2010 using rice straw, animal manure and sewage sludge as organic raw materials to make different mixtures. At the end of composting process, plant growth promoting bacteria (PGPB) was added to half of compost piles to study
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its effect on the quality of the compost. Twelve treatments in three replicates of compost piles were prepared.
5.7.1. Microbiological, physical and chemical changes during composting processes
5.7.1.1. Total microbial counts
The obtained results revealed that addition of manure to the compost mixture gave the highest values of all microbial counts. On the other hand, supplementation with sludge or inorganic accelerator gave the lowest records of the total microbial counts
Supplementation of bioaccelerator and PGPB increased the total bacterial counts since higher records were observed in the treatments which were treated with bioaccelerator and/or PGPB (T5, T8 and T11). In addition there was an increase in total microbial counts in the treatments which contain manure or sludge.
Concerning the fungi counts, the obtained results emphasized that the addition of manure increased the counts of fungi, while the lowest count of fungi was observed in the treatment of which inorganic accelerator was combined with bioaccelerator + PGPB. Moreover it is clearly that the treatments which contain manure increased total actinobacterial. Addition of PGPB slightly increased the total actinobacteria counts.
The highest record of total yeast was observed in treatment which received manure and supplemented with bioaccelerator and PGPB (53×103 cfu). On the other hand the lowest record was when sludge was
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added to the compost mixture (26 ×103 cfu). from the obtained results of total yeast it could be noticed that the addition of bioaccelerator and PGPB encouraged yeast growth.
The treatments which contain manure have the highest records of total thermocellulolytic bacteria. The treatments which contain bioaccelerator showed the highest record compared with other treatments which does not contain bioaccelerator.
Generally, the best treatment is the one containing the manure, which has the highest counts of fungi, actinobacteria, yeast and thermocellulolytic bacteria which consequently results in very high total count.
A positive relation can be noticed between the PGPB and the bio-accelerators (thermocelloselytic). Moreover, this positive relation is more pronounced in the case of manure.
5.7.1.2. Biological changes
The biological changes due to the use of bioaccelerators and PGPB were studied in the rice straw compost. The dehydrogenase, nitrogenase and phosphatase are measured in the twelve treatments at initial and final stages of composting.
There were significant increases in dehydrogenase activity in the treatments which contain bioaccelerator and/or PGPB. On the other hand, the treatments which contain sludge or manure showed the highest records of nitrogenase activity, and the addition of bioaccelerator and/or PGPB during composting significantly increased dehydrogenase activity as well, also there were significant increases in phosphatse activity.
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4.7.1.2.1. Dehydrogenase activity
The obtained data showed lower records of DHA in compost amended with chemical fertilizers (control) than the treatment of compost treated with bioaccelerators and/or PGPB. This result was observed in nearly all the experimental periods.
It is worthy to mention that DHA was increased in manure and sludge compost. In particular, DHA in compost treated with manure gave higher records than that amended with sludge.
The compost inoculated with bioaccelerators strains and PGPB in composting process gave the highest values of DHA. Especially the manure with amendments of bioaccelerators and PGPB showed higher records of DHA.
Generally, DHA in final compost increased as the number of sources of microorganisms increase. This was true under all investigated treatments of compost.
5.7.1.2.2. Nitrogenase activity
It is a logical result that, N2-ase activity was decreased in compost amended with chemical fertilizer compared with compost amended with manure and inoculated with bioaccelerators and PGPB. Lower values of N2-ase activity may be due to the inhibition of N2-ase activity with the amendment of inorganic nitrogen fertilizer at a high rate.
High records of N2-ase activity were observed in compost inoculated with PGPB only.
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Higher records of N2-ase activity were observed in compost inoculated with bioaccelartor strains (Bacillus circulans and Cellulomonas flavigena) than that treated with PGPB only.
The treatment amended with manure had the highest N2-ase activity in comparison with treatments amended with sludge.
Generally, compost amended with either manure or sludge had high biological activities. Enhancement of biological activities caused by organic matter might be due to the introducing of a large amount of living microorganisms and readily utilizable carbon source on which microorganisms live.
The highest values of N2-ase activity were obtained in compost amended with manure or sludge. Moreover, N2-ase activity in compost amended with PGPB was higher than unamended one.
5.7.1.2.3. Phosphatase activity
The records of phosphatase activity were widely affected with organic matter, bioaccelerators and PGPB amendment.
Results showed that phosphatase activity in the compost amended with organic matter was significantly higher than chemical amendment one.
Inoculation of compost with effective bioaccelerator strains led to a significant increase in phosphatase activity compared to chemical amendment. This result explained the beneficial effect of bioaccelerator strains in phosphatase production .
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Phosphatase activity was enhanced in compost inoculated and treated with PGPB and bioaccelerator compared to compost with either bioaccelerator or PGPB each one individually.
It is clear that the combination of manure, bioaccelerators and PGPB showed the greatest effect on increasing phosphatase activity. The highest records of phosphatase activity were observed in manure compost treated with the combination of bioaccelerator and PGPB .
Phosphatase activity recorded similar trend for sludge compost. Moreover, the sludge compost has lower values of the phosphatase activity than that of the manure compost.
Generally, phosphatase activity increased with the addition of organic matter and the presence of the P-dissolvers found in PGPB. Also, the chemical amendments suppress the phosphatase activity.
5.7.1.3. Physical and chemical analysis
5.7.1.3. 1. Physical changes
5.7.1.3. 1 .1.pH
pH records of composted wastes gave similar patterns. In all cases, they rise above the level of neutrality during the first four weeks, and then they come back about the level of neutrality during the last two weeks.
pH behaviors of the different treatment change in the same manner when the bioaccelerators were used.
5.7.1.3. 1 .2.Temperature
Temperature appeared to be elevated during the first three weeks then it falls down to the room temperature during the last four weeks. The treatments with the bioaccelerators show narrower
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temperature-distributions than the treatments without bioaccelerators. Maximal level of temperature was observed at the 3rd week and then gradually decreased up to the end of composting period (the 7th week) giving the lowest records. The recorded temperatures at the period of elevation were in the range of 60oC (for rice straw amended with the inorganic accelerator) to 67oC (for rice straw supplemented with organic, inorganic and biological accelerators).
- Physical analysis of the final compost
There were slight differences in pH for all treatments; in particular the pH slightly increases in T1, T4, T5 and T10.
On the other hand, records of EC which were determined of final compost samples were found to be restricted between 2.00-2.50 dS/m.
Furthermore, results of WHC which were determined in final compost samples indicate that there were differences between various treatments, the highest values were in treatments of T2, T5, T6 and T11, and the lowest values were in treatments of T1, T4 and T5.
pH of nearly all treatments was about 7 which indicates a neutral behavior of all treatments.
The use of bioaccelerators in the composting process has further improved the water holding capacity in which values reached about 200 percent in comparison with the treatments without bioaccelerators.
5.7.1.3.2. Chemical changes
The highest record in organic matter (OM %) was in treatments which contain sludge (T9, T12, T6, and T3). Addition of bioaccelerator and /or PGPB to composting process improves the organic matter. The highest records in organic carbon (OC %) were in treatments (T9, T12, T6 and T3).
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On the other hand total nitrogen achieved the highest records in treatments of T9, T12 and T3.
C/N ratio showed the same approximate values in all treatments except for some treatments there were slightly higher.
On the other hand, the highest records of potassium were observed in treatments of T6, T9 and T11, addition of sludge in composting process increased potassium.
Moreover, the highest values of total phosphorus were observed in treatments of T2 and T11. On the other hand, decrease of total phosphorus was noticed in treatments of T1, T4 and T10. Addition of PGPB in composting process improved the P%.
The use of farm manure and sludge in the composting process had increased the K+ content to reach an average value about 0.5 meq/100 gm compost. This is more than the double in comparison with the treatments without organic matter in which the K+ content was only 0.2 meq/100gm compost.
The N content has been greatly improved by the use of bioaccelerators to reach values as high as 6% to 7%. This in turn has been reflected to the C/N ratio which has been improved and reached very low values about 12.
The Pb content has not been affected when the bioaccelerators were used with the farm manures and domestic sludge. While the factory sludge contains very high Pb content that cannot be reduced by the bioaccelerators.
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The Cu content is found to be within the normal range in all treatments except those in which manure was used the Cu content was relatively low.
This experiment was carried out to study the effect of the best compost prepared with bioaccelerators (T5, T6, T8 and T9) on wheat plant growth and enzymatic activities of plant rhizosphere compared to chemical compost as (T1) control.
5.8.1. Effect of compost on dehydrogenase (DHA) in rhizosphere of wheat.
Lower records of DHA were observed in soil amended with compost produced from bioacceletors than soil amended with compost inoculated with PGPR.
Also, data showed that DHA records were higher in soil amended with compost produced by sludge than soil amended with compost produced by manure.
Generally, DHA was fluctuated during growth period. The higher records of DHA were noticed in tillering stage while the lowest records of DHA were observed in the grain formation stage.
5.8.2. Effect of compost on nitrogenase activity in rhizosphere of wheat.
Higher records of N2-ase activity were observed in soil amended with compost and inoculated with PGPR than soil treated with compost only. Soil treated with compost produced by sludge gave higher records
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of N2-ase activity compared to soil treated with compost produced by manure.
from obtained data it’s worthy to mention that the N2-ase activity values were higher at tillering stage rather than grain formation and maturity ones. Higher records of N2-ase activity in the initial period of growth may be due to beneficial effect of inoculation.
5.8.3. Effect of compost on phosphtase activity in rhizosphere of wheat
The values of phosphatase activity were widely affected with the type of compost. Obtained data showed increase of phosphatase activity records with soil treated with PGPR than untreated one. Also, data showed higher records of phosphatase activity in soil amended with compost produced by sludge compared with that amended with compost produced by manure.
The highest records of phosphtase activity were observed in soil amended with compost produced by sludge and inoculated with PGPR. Generally, phosphatase activity was remarkably high during the first stage of plant growth and then decreased progressively with plant growth and this result was true in all treatments.
5.8.4. Effect of compost on NPK content of wheat
Obtained data showed that N, P and K content increased in wheat grains of plants grown in soil amended with compost inoculated with PGPR than the uninoculated one. This result may be due to the role of nitrogen, phosphorus and potassium in soil fertility.
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5.8.5. Effect of compost on growth characteristics and yield of wheat
Plant height, number of panicles/plant and straw weight (g/ pot) in all treatments recorded no significant differences. On the other hand, using compost with biostimulators in wheat cultivation led to increase of 1000-grains weight (g), fresh weight of root system (g pot-1), dry weight of root system (g pot-1), fresh weight of shoot system (g pot-1) and dry weight of shoot system (g pot-1) compared with the control. While inoculation with PGPR recorded significant increase in all previous treatments in comparison with uninoculated one.
Also, data revealed that increase of grains weight (g.pot-1),1000 grain weight (g), fresh weight of root system (g pot -1), fresh weight of shoot system(g pot-1) and dry weight of shoot system (g pot-1) by using sludge compared with manure for preparing compost. It is worthily to mention that soil treated with sludge gave higher records in almost growth characteristics compared with compost treatments. The highest records of growth characteristics were shown in the treatment of soil treated with sludge compost, bio-stimulate and PGPR except No. of panicles -1 and straw weight (g plant-1).