Biosurfactant production by haloalkaliphilic Bacillus strains isolated from Red Sea, Egypt

This study aimed to produce biosurfactant by extremophilic marine bacteria. Twenty-one oil-spilled seawater samples were collected from Shalateen, Red Sea, Egypt. Two promising morphologically distinct biosurfactant-producing marine bacteria, SH20 and SH24, were selected. They were grown on minimal salt medium (MSM) and the biosurfactant production was evaluated and detected after 24 h using drop collapsing test, blood hemolysis, emulsification index and surface tension. SH20 and SH24 isolates showed the highest emulsification index 57 and 56%, respectively, and have positive results for hemolysis and drop collapse. The two isolates were identified using 16 S rRNA as Bacillus amyloliquefaciens SH20 and Bacillus thuringiensis SH24. Stability of biosurfactant production by both strains was observed at moderate temperature (30 °C), high alkalinity at pH (11) and high salt concentration (15%). An increase of emulsification index tended to be 60 and 69%, respectively, considering the two strains haloalkiphilic bacteria. To study the stability mechanism for extremophilic biosurfactant producers, the protein profile was determined using SDS-PAGE electrophoresis showing some new detected proteins depends on their culturing conditions. Partially purified biosurfactant from the most active strain B. amyloliquefaciens SH20 was chemically determined by FTIR and GCâMS analysis showed characteristic bands, revealed the presence of non-anionic didemnin surfactant. Keywords: Biosurfactant, Haloalkaliphiles, Bacillus sp, SDS-PAGE, FTIR, GCâM

Protective effect of squilla chitosan–silver nanoparticles for Dicentrarchus labrax larvae infected with Vibrio anguillarum

Abstract Antimicrobial nanoparticle therapy was proposed as an alternative strategy to reduce the use of antibiotics in larval-rearing systems. Antibacterial potential of the prepared squilla chitosan–silver nanoparticles and its protective effect on Dicentrarchus labrax (sea bass) larvae in the early stages were studied against Vibrio angularium. Different concentrations of squilla chitosan (Csq) and squilla chitosan–silver nanoparticles (Csq–AgNps) (1, 2, 5, 10, and 20 %) were, in vitro, tested against V.anguillarum and expressed as a role of Log10 mean. Sea bass larvae were treated using: 10 % Csq and 5 % Csq–AgNps as effective inhibitory concentrations against the pathogen either encapsulated during the feeding regime or added directly to the model system via the water from the onset of 4 weeks. The long-term administration of Csq–AgNps through enriched food for both non-infected and infected systems had survival % of 74.5 ± 1.5 and 72.5 ± 2.5, respectively. Larval clinical observations using Csq–AgNps were studied compared with the two controls. The current study found that 5 % encapsulated Csq–AgNps was enough to suppress infection and considered as an alternative to antibiotics in controlling virulent fish pathogens

GC/MS spectroscopic approach and antifungal potential of bioactive extracts produced by marine macroalgae

The antifungal activity and the chemical constituents of selected macroalgae collected from the Egyptian Mediterranean coast of Alexandria have been investigated. Agar well diffusion assay was used to determine the antifungal potential of the extractable matter against Fusarium solani, Fusarium oxysporum, Tricoderma hamatum, Aspergillus flavipes and Candida albicans. The ethyl acetate and methanolic extracts (ULE2 and ULM5) of Ulva lactuca obtained from Al Selsela exhibited the highest activity with (AI) = 1.05 ± 0.053 and 1.03 ± 0.052, respectively, compared with fluconazole. However, the methanolic extract of U. lactuca (ULM1) from Abu Qir Bay showed (AI) = 0.73 ± 0.037. This followed by methanolic extracts of Pterocladia capillacea (PCM1: AI = 0.70 ± 0.035 and Ulva fasciata (UFM1: AI = 0.69 ± 0.035). GC/MS analysis of ULM1 and ULM5 indicated the existence of different constituents revealing ecological impacts. The methanolic extract (UFM1) contains six major components including palmitic acid, methylester, trichloromethyloxirane, linolenic acid, ethylester, 3,7,11,15-tetramethyl-2-hexadecen-1-ol, 11-octadecenoic acid, methylester and 12,15-octadecadienoic acid, methylester. High percentages of palmitic acid, n-heptacosane, 2-methylhexadecan-1-ol, methoxy acetic acid, 2-tridecylester and myristic acid are found in the methanolic extract of P. capillacea (PCM1). Most of the identified components have been reported to possess antimicrobial activity that could be responsible for the antifungal potential reported in the present study

A pilot system integrating a settling technique and a horizontal subsurface flow constructed wetland for the treatment of polluted lake water

Summarization: An integrated system was tested at pilot-scale for treating polluted water from the Marriot Lake in Egypt, comprising a settling technique followed by three parallel horizontal subsurface flow constructed wetland (HFCWs) units operating under a continuous flow mode; one HFCW unit was planted with Typha angustifolia and contained a perforated pipes network for enhanced passive aeration (CWA), one unit was planted without the perforated pipe network (CWR) and one served as a Control unit (unplanted and without perforated pipes). Changes in physicochemical parameters, BOD5, nutrients (nitrogen, phosphorus), microbial community, and trace metals at different hydraulic retention times (HRT; 0.5–6 h) and hydraulic loading rates (HLR; 750, 1000, 1250, and 2000 L/m2/d) were monitored. The CWA unit had an overall better performance than the CWR unit, while both planted units outperformed the Control unit. CWA showed the highest performance at HLR of 1000 L/m2/d and 4-6 h-HRT with 95.3% removal for turbidity, 83% for BOD5, 99.3% for ammonia nitrogen (NH4–N), 70.8% for Total Nitrogen (TN), and 66.7% for Total Phosphorus (TP), while higher NO3–N and NO2–N effluent concentrations were observed. Trace metals levels were significantly reduced and accumulated in plant tissues. Microbial communities’ densities fluctuated in the CWA unit. The integrated system with the settling stage and the planted CWA unit was proved to achieve a high removal efficiency and reached the national discharge limits, thus representing a novel nature-based solution for the sustainable remediation of polluted lake water.Presented on: Chemospher