Sulaiman A. Alrumman

Enzymatic saccharification and fermentation of cellulosic date palm wastes to glucose and lactic acid

The bioconversion of cellulosic wastes into high-value bio-products by saccharification and fermentation processes is an important step that can reduce the environmental pollution caused by agricultural wastes. In this study, enzymatic saccharification of treated and untreated date palm cellulosic wastes by the cellulases from Geobacillus stearothermophilus was optimized. The alkaline pre-treatment of the date palm wastes was found to be effective in increasing the saccharification percentage. The maximum rate of saccharification was found at a substrate concentration of 4% and enzyme concentration of 30 FPU/g of substrate. The optimum pH and temperature for the bioconversions were 5.0 and 50 °C, respectively, after 24 h of incubation, with a yield of 31.56 mg/mL of glucose at a saccharification degree of 71.03%. The saccharification was increased to 94.88% by removal of the hydrolysate after 24 h by using a two-step hydrolysis. Significant lactic acid production (27.8 mg/mL) was obtained by separate saccharification and fermentation after 72 h of incubation. The results indicate that production of fermentable sugar and lactic acid is feasible and may reduce environmental pollution by using date palm wastes as a cheap substrate.

Effects of different sewage sludge applications on heavy metal accumulation, growth and yield of spinach (Spinacia oleracea L.).

ABSTRACT In this study, we present the response of spinach to different amendment rates of sewage sludge (0, 10, 20, 30, 40 and 50 g kg−1) in a greenhouse pot experiment, where plant growth, biomass and heavy metal uptake were measured. The results showed that sewage sludge application increased soil electric conductivity (EC), organic matter, chromium and zinc concentrations and decreased soil pH. All heavy metal concentrations of the sewage sludge were below the permissible limits for land application of sewage sludge recommended by the Council of the European Communities. Biomass and all growth parameters (except the shoot/root ratio) of spinach showed a positive response to sewage sludge applications up to 40 g kg−1 compared to the control soil. Increasing the sewage sludge amendment rate caused an increase in all heavy metal concentrations (except lead) in spinach root and shoot. However, all heavy metal concentrations (except chromium and iron) were in the normal range and did not reach the phytotoxic levels. The spinach was characterized by a bioaccumulation factor <1.0 for all heavy metals. The translocation factor (TF) varied among the heavy metals as well as among the sewage sludge amendment rates. Spinach translocation mechanisms clearly restricted heavy metal transport to the edible parts (shoot) because the TFs for all heavy metals (except zinc) were <1.0. In conclusion, sewage sludge used in the present study can be considered for use as a fertilizer in spinach production systems in Saudi Arabia, and the results can serve as a management method for sewage sludge.

In vitro antifungal activity of Argemone ochroleuca Sweet latex against some pathogenic fungi

The in vitro antifungal activities of crude latex of Argemone ochroleuca Sweet against four clinical isolates of Candida (Candida albicans, Candida glabrata, Candida krusei and Candida tropicalis) and six isolates of plant pathogenic fungi (Alternaria alternate, Drechslera halodes, Fusarium oxysporum, Macrophomina phaseolina, Pythium ultimum and Rhizoctoina solani) were assessed using well diffusion method. The chemical compounds of the hexan extract of A. ochroleuca latex were investigated using Perkin-Elmer Gas chromatography-Mass spectrometry. The latex of A. ochroleuca showed antifungal activity against D. halodes (10.60 mm) and Candida spp. (15.06 to 20.16 mm). GC-MS analysis of the hexan extract of A. ochroleuca latex revealed that the latex contains diethyl phthalate (81.57%), 6-Nitro-imidazo(1,2-a)pyridine compound (8.833%), cyclohexasiloxane, dodecamethyl(5.607%), 4-(2,2-Dimethyl-6-methylenecyclohexylidene)-3-methylbutan-2-one compound (2.410%) and cycloheptasiloxane, tetradecamethyl- (1.574%). These findings indicate that the latex of A. ochroleuca could be a good source of antifungal agent against D. halodes and Candida spp. and the phytocomponents present in the latex could be used against fungal pathogens.

Antibacterial activity of Miswak Salvadora persica extracts against isolated and genetically identified oral cavity pathogens

BACKGROUND Despite medical progress worldwide, dental caries are still widespread. Miswak is derived from the plant Arak (Salvadora persica). It is used by Muslim peoples as a natural product for the cleansing of teeth, to ensure oral and dental hygiene. OBJECTIVE This study was conducted to evaluate the antimicrobial effects of ethanol, methanol, and ethanol/methanol extracts of Miswak against three bacterial pathogens of the oral cavity. METHODS The pathogens were isolated from the oral cavity of volunteers/patients and were identified on the basis of 16S rRNA gene amplification data. Sequence comparisons were made with 16S rRNA gene sequences available in the GenBank database. RESULTS The results of sequence alignment and phylogenetic analysis identified the three pathogens as being Staphylococcus aureus strain KKU-020, Enterococcus faecalis strain KKU-021 and Klebsiella pneumoniae strain KKU-022. All Miswak extracts showed powerful antimicrobial activity against the three pathogens. The maximum zone of inhibition (40.67 ± 0.88 mm) was observed against E. faecalis KKU-021 with ethanolic extracts whilst methanolic extracts showed the minimum zone of inhibition (10.33 ± 0.88 mm) against K. pneumonia KKU-022. CONCLUSION Based upon the significant effects of the Miswak extracts, against the oral cavity pathogens in our study, we recommend that Miswak could be used as a dental hygiene method to prevent tooth caries.

Biodegradation and detoxification of aliphatic and aromatic hydrocarbons by new yeast strains

Seeking new efficient hydrocarbon-degrading yeast stains was the main goal of this study. Because microorganisms are greatly affected by the environmental factors, the biodegradation potentiality of the microorganisms varies from climatic area to another. This induces research to develop and optimize the endemic organisms in bioremediation technology. In this study, 67 yeast strains were tested for their growth potentiality on both aliphatic and aromatic hydrocarbons. The most efficient six strains were identified using sequence analysis of the variable D1/D2 domain of the large subunit 26S ribosomal DNA. The identity of these strains was confirmed as Yamadazyma mexicana KKUY-0160, Rhodotorula taiwanensis KKUY-0162, Pichia kluyveri KKUY-0163, Rhodotorula ingeniosa KKUY-0170, Candida pseudointermedia KKUY-0192 and Meyerozyma guilliermondii KKUY-0214. These species are approved for their ability to degrade both aliphatic and aromatic hydrocarbons for the first time in this study. Although, all of them were able to utilize and grow on both hydrocarbons, Rhodotorula taiwanensis KKUY-0162 emerged as the best degrader of octane, and Rhodotorula ingeniosa KKUY-170 was the best degrader of pyrene. GC-MS analysis approved the presence of many chemical compounds that could be transitional or secondary metabolites during the utilization of the hydrocarbons. Our results recommend the application of these yeast species on large scale to approve their efficiency in bioremediation of oil-contamination of the environment. Using these yeasts, either individually or in consortia, could offer a practical solution for aquatic or soil contamination with the crude oil and its derivatives in situ.

Colorimetric Sensing of Toxic Metal and Antibacterial Studies by Using Bioextract Synthesized Silver Nanoparticles

Here, we report the simple and cost effective colorimetric technique for the determination of toxic metals (Hg2+) in aqueous sample by using bioextract silver nanoparticles (AgNPs). The indigenous AgNPs were synthesised by green and ecologically friendly style using extract of fig (Ficus carica) leaf. The synthesized AgNPs were confirmed by UV–vis spectroscopy, FT-IR spectroscopy, and scanning electron microscopy methods. The synthesis of AgNPs was observed by its colour changing from light yellow to dark brownish. The existence of furanocoumarins bioactive materials in the fig leaf extract, which act as bio-reducing and capping agent, help in the formation of stabilized silver nanoparticles. In addition, the bacterial activity of the synthesized silver nanoparticles was tested against gram-negative (Klebsiella oxytocam, Pseudomonas aeruginosam, Shigella flexneri and Proteus mirabilis), gram-positive (Staphylococcus aureus and Micrococcus luteus) and one Candida (Candida albicans) human pathogen and the results showed moderate activity.

Screening and genetic identification of acidic and neutral protease-producing yeasts strains by 26S rRNA gene sequencing

Protease enzymes (proteases), particularly those produced by microorganisms, play very important roles in industry, due to their diverse applications. Considering the richness of microbial diversity in nature, a good chance always exists that proteases more suitable, with better properties for commercial application, may be discovered while screening novel microorganisms from local environments. In this study, 94 yeasts were isolated from different natural sources collected from the Abha region, Kingdom of Saudi Arabia, to determine extracellular protease production and activity. Among them, 23 isolates (24.46%) showed protease activity using a casein hydrolysis test. Of these, five isolates (21.74%) were selected and identified as the best protease producers by exhibiting the largest clearance zones around colonies. A 26S rRNA gene D1/D2 domain sequence alignment, comparison, and phylogenetic analysis of our study yeasts to published D1/D2 domain rRNA gene sequences from GenBank, identifies the isolates as Rhodotorula mucilaginosa KKU-M12c, Cryptococcus albidus KKU-M13c, Pichia membranifaciens KKU-M18c, Hanseniaspora uvarum KKU-M19c, and Candida californica KKU-M20c. The influence of varying pH (4.0–9.0) on the yield and activity of the proteases was investigated using 0.5% (w/v) casein as a substrate, to detect optimum pH values for yeast extracellular protease production. Enzyme activity was measured using qualitative and quantitative assays. Results show all of the study yeasts secreting protease enzyme at all tested pH levels, with the exception of pH 9.0. This indicates that none of the five yeasts are alkaline protease producers. Maximum protease activity (187 U/mL) was observed in strain H. uvarum KKU-M19c at pH 6.0 (only), indicating that strain KKU-M19c only produces neutral protease. The other four yeast isolates, R. mucilaginosa KKU-M12c, C. albidus KKU-M13c, P. membranifaciens KKU-M18c, and C. californica KKU-M20c, produced both acidic (at pH 4.0) and neutral (at pH 6.0 and 7.0) proteases. Strain C. californica KKU-M20c was found to be the best acidic and neutral protease producer (138 U/mL at pH 4.0, and 185 U/mL at pH 7.0). This is the first report of the discovery and isolation of local, powerful yeasts producing acidic and neutral protease enzymes from the Abha region, Kingdom of Saudi Arabia.

Variations in genetic and chemical constituents of Ziziphus spina-christi L. populations grown at various altitudinal zonation up to 2227 m height

Altitudinal gradient-defined specific environmental conditions could lead to genetics and chemical variations among individuals of the same species. By using RAPD, ISSR, GC–MS and HPLC analysis, the genetic and chemical diversity of Ziziphus spina-christi plants at various altitudinal gradient namely; Abha (2227.86 m), Dala Valley (1424 m), Rakhma Valley (1000 m), Raheb Valley (505 m) and Al-Marbh (147 m) were estimated. RAPD markers revealed that the highest similarity value (40.22%) was between Raheb Valley and Al-Marbh while the lowest similarity (10.08%) was between Abha and Raheb Valley. Based on ISSR markers the highest similarity value (61.54%) was also between Raheb Valley and Al-Marbh, while the lowest similarity (26.84%) was between Abha and Rakhma Valley. GC–MS results showed the presence of various phytochemical constituents in each population. The dendrogram based on chemical compounds separated the Z. spina-christi grown at the highest elevations (Abha) from the populations in lower elevations. HPLC analysis showed that the leaves of Z. spina-christi plant contain considerable amount of vitamins including B1, B12, B2 and folic acid. In conclusion, there is a close relation between altitudinal gradients, genetic diversity and chemical constituents of the leaves of Z. spina-christi plants.

An application of genetics-chemicals constituents to the relatedness of three Euphorbia species

Abstract Genetics and chemicals relatedness among three Euphorbia species (Euphorbia prostrata Aiton, Euphorbia peplus L. and Euphorbia terracina L.) were analysed by RAPD, ISSR markers and GC-MS technique. RAPD profiling pattern revealed that E. peplus and E. terracina in one cluster with similarity value (44.37%) while the lowest value (29.14%) between E. prostrata and E. terracina. ISSR profiling pattern revealed that E. prostrata and E. terracina in one cluster with similarity value (46.75%) and the lowest similarity value (37.87%) between E. prostrata and E.peplus. The sum results of RAPD and ISSR data revealed that E. peplus and E. terracina in one cluster with similarity value (44.69%) while the lowest value (36.88%) between E. prostrata and E. peplus. Sixty-eight chemicals pattern revealed that E. prostrata and E. peplus in one cluster with similarity value (39.71%) while the lowest value (25.0%) between E. prostrata and E. terracina. Super tree (RAPD, ISSR and phytocomponents) revealed that E. peplus and E. terracina in one cluster with similarity value (43.04%) while the lowest value (36.08%) between E. terracina and E. prostrata. In conclusion, biosystematics tools including biomarkers and chemical compounds can be applied to investigate relatedness of Euphorbia species and probably to other plant taxa.

Role of Soil Amendment with Micronutrients in Suppression of Certain Soilborne Plant Fungal Diseases: A Review

Micronutrients might affect the resistance of plants to pathogens or disease tolerance. In addition, there are conflicting reports about the effect of micronutrients on plant diseases, and many features that impact this response are unclear. Soil is crucial for micronutrient storage such as Br, Mn, Zn, Cu, Fe and Cl, which can reduce the severity of plant disease by increasing disease tolerance and resistance of plants to pathogens. In particular, micronutrients have significant effects on controlling soilborne plant fungal diseases. Micronutrients can reduce disease to a satisfactory level or at least to a level at which further control by other conventional organic biocides or traditional practices is cheap and more fruitful. This review article recaps the latest information concerning the effect of micronutrients, such as Br, Mn, Zn, Cu, Fe, Cl and Mo, on disease resistance and tolerance and their use in sustainable agriculture. Here, our main focus is the critical analysis of various factors responsible for the suppression of certain plant fungal diseases due to micronutrients. In addition, we have identified efforts to determine key areas where sincere research efforts are still needed to develop strategies for manipulating micronutrient application in such a way that it could be more efficiently utilised in managing soilborne plant fungal diseases.