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Abstract Isolation and identification of the indigenous yeasts of the rotten date fruits for possible production of bioethanol and singlecell protein was the aim of this study. Results showed that a considerable amount of date fruits is subjected to unfavorable conditions of storage that induce their rot and spoilage. From the rotten date fruits, ten yeast isolates were obtained and genetically identified by the sequence of D1/D2 domain of the 26S rRNA gene and phylogenetic analysis. The identity of these yeasts was: Hanseniaspora guilliermondii, H. uvarum (2 strains), H. opuntiae, Pichia kudriavzevii (2 strains), Issatchenkia orientalis, Wickerhamomyces anomalus, Yarrowia lipolytica and Zygosaccharomyces rouxii. The ability of these strains to ferment 20% of the spoilage date fruit juice evaluated on laboratory scale. Results proved that P. kudriavzevii KKUY-0151 and H. uvarum KKUY-0153 yielded 67.48 and 67.37 g/L respectively, of bioethanol as the highest producers. However, H. uvarum KKUY-0078, H. guilliermondii KKUY-0009 and Z. Rouxii KKUY-0157 produced the highest fresh biomass weight 31.76, 30.96 and 30.69 g/L, respectively as a single cell protein production. The study is a pioneer to investigate the endemic yeasts of the rotten date fruits. It concludes that some of the indigenous yeasts of the rotten date fruits are promising organisms in recycling the substrate into valuable products such as bioethanol and single-cell protein.

Abstract Isolation and identification of the indigenous yeasts of the rotten date fruits for possible production of bioethanol and singlecell protein was the aim of this study. Results showed that a considerable amount of date fruits is subjected to unfavorable conditions of storage that induce their rot and spoilage. From the rotten date fruits, ten yeast isolates were obtained and genetically identified by the sequence of D1/D2 domain of the 26S rRNA gene and phylogenetic analysis. The identity of these yeasts was: Hanseniaspora guilliermondii, H. uvarum (2 strains), H. opuntiae, Pichia kudriavzevii (2 strains), Issatchenkia orientalis, Wickerhamomyces anomalus, Yarrowia lipolytica and Zygosaccharomyces rouxii. The ability of these strains to ferment 20% of the spoilage date fruit juice evaluated on laboratory scale. Results proved that P. kudriavzevii KKUY-0151 and H. uvarum KKUY-0153 yielded 67.48 and 67.37 g/L respectively, of bioethanol as the highest producers. However, H. uvarum KKUY-0078, H. guilliermondii KKUY-0009 and Z. Rouxii KKUY-0157 produced the highest fresh biomass weight 31.76, 30.96 and 30.69 g/L, respectively as a single cell protein production. The study is a pioneer to investigate the endemic yeasts of the rotten date fruits. It concludes that some of the indigenous yeasts of the rotten date fruits are promising organisms in recycling the substrate into valuable products such as bioethanol and single-cell protein.

ABSTRACT Sixty one thermoalkalophilic bacteria were isolated from soil samples in Saudi Arabia’s southern region. Isolate TA-38, obtained from the Tanomah region, showed the best performance for enzyme production and was submitted for further study. It was identified as Bacillus axarquiensis based on 16S rRNA gene sequencing studies. The feasibility of using potato waste water as a simple and cheap medium for the production of α- amylase was evaluated compared with starch broth medium. The production of α-amylase in the potato waste water medium was only 13.8% less than that of the starch medium. Maximum enzyme production was achieved after 48 hours of cultivation at the beginning of the stationary phase at pH 10.0 and 50 0C. The appropriate addition of starch; nitrogen; phosphate; and calcium to potato waste water significantly enhanced the production of α-amylase. The enzyme production reached a maximum of 64.5 Uml-1 with the potato wastewater adding with 0.5 % starch; 0.4 % yeast extract; 0.04% CaCl2-2H2O and 0.05 % KH2PO4. The optimization of the potato waste water medium led to an approximately 4.02 fold increase in the production of α-amylase compared to starch broth medium. Data indicated that the potato waste water contained substrates which could be used by bacterial isolate for the production of α-amylase production and the developed procedure was cost effective since it requires only a slightly addition of nutrients to the medium.

Abstract Sulfate-reducing bacteria (SRB) are widely used for heavy metal (HM) treatment in bioreactors but their growth and biological activity can be inhibited by such treatment. Here, bioreactor experiments were used to investigate changes in the SRB community and the copy number of the dissimilatory sulfite reductase β-subunit functional gene (dsrB) under high doses of sulfates and HMs. The SRB community was investigated using polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and sequencing techniques, while the dsrB gene abundance was measured by quantitative real-time PCR (qRT-PCR). The sulfate reduction rate was initially much higher in reactors without HMs than in those containing HMs (p = 0.001). Sulfate levels were reduced by 50% within the first 3 days of operation. As a result, the HM removal rate was initially much lower in the reactors containing HMs. Most of the HMs reduced to safe limits within 9 ~ 12 days of operation. The SRB community mainly consisted of Desulfovibrio vulgaris, D. termitidis, D. desulfuricans, D. simplex and Desulfomicrobium baculatum, as determined by PCR-DGGE. qRT-PCR revealed a decreasing trend in the copy numbers of a functional gene (dsrB) after 6 days in samples lacking HMs; however, the opposite trend was observed in the HM-containing samples.

his study presents the first results about the genetic polymorphism and diversity among the five Egyptian Bulinus truncatus populations, Giza (GZ), Damietta (DM), Behera (BH), Fayoum (FY) and lab bred strain (LB), using the inter - simple sequence repeats PCR (ISSR - PCR). A total of 85 bands, unique, polymorphic and monomorphic were obtained using 10 ISSR primers. Out of them, 28 bands were polymorphic. Among B. truncatus populations, the highest polymorphism (57.1%) was revealed by the primer ISSR1, followed by that revealed by ISSR7 (40%). However, the lowest polymorphism was 16.6% and resulted from application of ISSR6 and ISSR 8 primers. ISSR5, ISSR7, ISSR9 and ISSR10 primers revealed four unique bands of size 389, 199, 139 and 154 bp respectively for FY population. All bands resulted from application of ISSR4 primer were monomorphic. Genetic similarity and relationship between the five populations were detected using cluster analysis. The high genetic variability obtained from ISSR markers showed diverges of FY population from the others which may be interpreted by located Fayoum region in an isolated area from the Nile Valley. It was noted the presence of a high level of genetic similarity between GZ and LB populations, that may be due to the origin of LB was from Giza governorate. Our results have provided evidence for the usefulness of ISSR markers to analyze genetic variab ility among B. truncatus populations.

Abstract Natural rubber latex is one of the problems that raises the environmental concerns. In this study the degrading ability of Ficus elastica rubber latex by a bacterium strain ASU-03, isolated from Egyptian soil was assessed. The strain was able to produce clear zone around its colony on latex rubber containing medium and was identified by conventional methods as Streptomyces sp. Phylogenetic analysis of 16S rRNA (16S rRNA) and RNA polymerase ß-subunit (rpoB) genes were applied. Results of the 16S rRNA gene analysis revealed that the strain was highly related to Streptomyces sp. (100% similarity), so the rpoB gene was partially sequenced to clarify the specific name of the isolate. Phylogenetic tree based on rpoB gene sequences indicated that strain ASU-03 was highly similar to the reference strain Streptomyces labedae and both were shared a one cluster. The current results demonstrated that the use of a rpoB gene-based method gives a better resolution in the species level identification. To our knowledge, this species has never been reported to be involved in natural rubber degradation. This was therefore the first report about the degradation of Ficus elastic by S. labedae. The degradation of Ficus elastica rubber latex was determined by measuring the increase in protein content of bacterium (mg/g dry wt), reduction in molecular weight (g/mol) and inherent viscosity (dL/g) of the latex. Moreover the degradation was also confirmed by formation of aldehyde or keto group by Schiff’s reagent and by observing the growth of the Streptomyces strain using scanning electron microscopy.

Abstract Natural rubber latex is one of the problems that raises the environmental concerns. In this study the degrading ability of Ficus elastica rubber latex by a bacterium strain ASU-03, isolated from Egyptian soil was assessed. The strain was able to produce clear zone around its colony on latex rubber containing medium and was identified by conventional methods as Streptomyces sp. Phylogenetic analysis of 16S rRNA (16S rRNA) and RNA polymerase ß-subunit (rpoB) genes were applied. Results of the 16S rRNA gene analysis revealed that the strain was highly related to Streptomyces sp. (100% similarity), so the rpoB gene was partially sequenced to clarify the specific name of the isolate. Phylogenetic tree based on rpoB gene sequences indicated that strain ASU-03 was highly similar to the reference strain Streptomyces labedae and both were shared a one cluster. The current results demonstrated that the use of a rpoB gene-based method gives a better resolution in the species level identification. To our knowledge, this species has never been reported to be involved in natural rubber degradation. This was therefore the first report about the degradation of Ficus elastic by S. labedae. The degradation of Ficus elastica rubber latex was determined by measuring the increase in protein content of bacterium (mg/g dry wt), reduction in molecular weight (g/mol) and inherent viscosity (dL/g) of the latex. Moreover the degradation was also confirmed by formation of aldehyde or keto group by Schiff’s reagent and by observing the growth of the Streptomyces strain using scanning electron microscopy.

Abstract Natural rubber latex is one of the problems that raises the environmental concerns. In this study the degrading ability of Ficus elastica rubber latex by a bacterium strain ASU-03, isolated from Egyptian soil was assessed. The strain was able to produce clear zone around its colony on latex rubber containing medium and was identified by conventional methods as Streptomyces sp. Phylogenetic analysis of 16S rRNA (16S rRNA) and RNA polymerase ß-subunit (rpoB) genes were applied. Results of the 16S rRNA gene analysis revealed that the strain was highly related to Streptomyces sp. (100% similarity), so the rpoB gene was partially sequenced to clarify the specific name of the isolate. Phylogenetic tree based on rpoB gene sequences indicated that strain ASU-03 was highly similar to the reference strain Streptomyces labedae and both were shared a one cluster. The current results demonstrated that the use of a rpoB gene-based method gives a better resolution in the species level identification. To our knowledge, this species has never been reported to be involved in natural rubber degradation. This was therefore the first report about the degradation of Ficus elastic by S. labedae. The degradation of Ficus elastica rubber latex was determined by measuring the increase in protein content of bacterium (mg/g dry wt), reduction in molecular weight (g/mol) and inherent viscosity (dL/g) of the latex. Moreover the degradation was also confirmed by formation of aldehyde or keto group by Schiff’s reagent and by observing the growth of the Streptomyces strain using scanning electron microscopy.