Efficiencies of local bacterial isolates in malathion degradation were investigated. Five bacterial isolates obtained from agricultural waste water were selected due to their ability to grow in minimal salt media, supplied with 250 ppm malathion as sole source of carbon and phosphorus. The purified bacterial isolates (MOS-1, MOS-2, MOS-3, MOS-4 and MOS-5) were characterised and identified using a combination of cellular profile (SDS-PAGE), genetic make up profile (RAPD-PCR), and morphological and biochemical characteristics. Four bacterial isolates (MOS-1, MOS-2, MOS-3 and MOS-4) with identical genetic characteristics were identified as Enterobacter aerogenes, whereas isolate MOS-5 was identified as Bacillus thuringiensis. The degradation rate of malathion in liquid culture was estimated during 15 days of incubation for the isolate MOS-5 of B. thuringiensis. Slightly more than 50% of the initial malathion was decomposed within 3 days. The malathion concentration decreased to almost 17% in the inoculated medium after 10 days incubation, while more than 91% of the initial malathion was degraded after 15 days.

Due to the scarcity of water resources and the harmful effects of sewage on water bodies, water purification becomes an important issue. The application of ultrasonic waves is a novel technique developed for water purification. This technology works as an advanced method of oxidation, contributing to the elimination of various types of contaminants. The basic principle of ultrasound is based on the destruction of both bacterial cells and difficult todegrade organics. A brief overview of water purification methods, application of ultrasound, ultrasound waves theory and the benefits and drawbacks of using ultrasound waves in water purification will be discussed in this article. In addition, the role of ultrasound waves in the degradation of various organic contaminants, microbial pollutant disinfection, and other pollutants removal.

Background Drought stress is one of the major abiotic stresses that adversely affect rice production. Four rice genotypes, Giza177, IR64 (as sensitive genotypes) and Vandana, Orabi3 (as tolerant genotypes) were used to screen and characterize the soil microbes associated with each genotype under drought stress. Results The soil microbes associated with the tolerant genotypes showed high drought tolerance and high levels of enzyme activity. The most drought-tolerant isolates were inoculated with the sensitive genotype Giza177 under drought conditions. Some morphological, biochemical and molecular responses of inoculated plants were estimated. Inoculated plants showed regulation of some growth and stress-related genes (COX1, AP2-EREBP, GRAM, NRAMP6, NAM, GST, DHN and three genes of expansin (EXP1, EXP2 and EXP3) under drought conditions. Expression profiling of these genes were highly induced in plants inoculated with 4E11 and were correlated with improved growth status under drought stress. Conclusion Based on this, drought-tolerant plant growth-promoting rhizobacteria (PGPRs) were associated with the drought-tolerant genotype (Orabi 3). They were related to the significant increase in soil enzymes activities (dehydrogenase, nitrogenase, urease and alkaline phosphatase) in the rhizosphere of tolerant genotype. Inoculation the drought-sensitive genotype (Giza 177) with the most drought-tolerant isolates improved the tolerance status of the sensitive rice genotype and induced the expression of some growth and stress-responsive genes. AP2-EREBP, NRAMP6, DHN and all expansin genes (EXP1, EXP2 and EXP3) were the highly induced genes in inoculated plants with 4E11 strain and the consortium of three selected strains under drought condition. Graphic abstract

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Microalgal biomass is one of the most promising third-generation feedstocks for bioethanol production because it contains signi cantly reduced sugar amounts which, by separate hydrolysis and fermentation, can be used as a source for ethanol production. In this study, the defatted microalgal biomass of Nannochloropsis oculata (NNO-1 UTEX Culture LB 2164) was subjected to bioethanol production through acid digestion and enzymatic treatment before being fermented by Saccharomyces cerevisiae (NRRLY-2034). For acid hydrolysis (AH), the highest carbohydrate yield 252.84 mg/g DW was obtained with 5.0% (v/v) H 2 SO 4 at 121°C for 15 min for defatted biomass cultivated mixotrophically on SBAE with respect to 207.41 mg/g DW for defatted biomass cultivated autotrophically (control treatment), Whereas, the highest levels of reducing sugars was obtained With 4.0%(v/v) H 2 SO 4 157.47 ± 1.60 mg/g DW for defatted biomass cultivated mixotrophically in compared with 135.30 mg/g DW for the defatted control treatment. The combination of acid hydrolysis 2.0% (v/v) H 2 SO 4 followed by enzymatic treatment (AEH) increased the carbohydrate yields to 268.53 mg/g DW for defatted biomass cultivated mixotrophically on SBAE with respect to 177.73 mg/g DW for the defatted control treatment. However, the highest levels of reducing sugars were obtained with 3.0% (v/v) H 2 SO 4 followed by enzyme treatment gave 232.39 ± 1.77 for defatted biomass cultivated mixotrophically on SBAE and 150.75 mg/g DW for the defatted control treatment. The sugar composition of the polysaccharides showed that glucose was the principal polysaccharide sugar (60.7%-62.49%) of N. oculata defatted biomass. Fermentation of the hydrolysates by Saccharomyces cerevisiae for the acid pretreated defatted biomass samples gave ethanol yield of 0.86 g/l (0.062 g/g sugar consumed) for control and 1.17 g/l (0.069 g/g sugar consumed) for SBAE mixotrophic. Whereas, the maximum ethanol yield of 6.17 ± 0.47 g/l (0.26 ± 0.11 g/g sugar consumed) was obtained with samples from defatted biomass grown mixotrophically (SBAE mixotrophic) pretreated with acid coupled enzyme hydrolysis.

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