Mycoremediation effect of Trichoderma harzianum strain T22 combined with ozonation in diesel-contaminated sand

This study aimed to determine the ability of the fungus Trichoderma harzianum strain T22 (Th-T22) to utilize diesel fuel as a carbon source. The potential use of Th-T22 for diesel bioremediation in an artificial soil was tested by inoculating a diesel-sand mixture with a fungal mycelial suspension of Th-T22. Given the ability of ozone to degrade compounds with low biochemical reactivity, the effect of a pre- and post-ozonation was also evaluated. The survival, growth and sporulation of Th-T22 throughout the bioremediation trial were monitored in all the treatments. In the post-ozonation treatments, the biodegradation percentages of diesel removal were 70.16% and 88.35% in Th-T22-inoculated sand treated or untreated with the antibacterial streptomycin, respectively. The results showed that ozonation alone caused good removal efficiencies (41.9%) but it was much more effective if combined with Th-T22 in a post-ozonation regime, whereas pre-ozonation negatively affected the subsequent biodegradation, likely due to its disinfectant and oxidizing effect on Th-T22. The results obtained demonstrated the significant mycoremediation ability of Th-T22 in diesel-contaminated sand and its possible use as a bioremediation agent for diesel spills in polluted sites.

Biological investigations of essential oils extracted from three Juniperus species and evaluation of their antimicrobial, antioxidant and cytotoxic activities

AIMS

To conduct biological investigations and to evaluate the antimicrobial and antioxidant activities of the essential oils (EOs) extracted from Juniperus communis, J. scopulorum and J. horizontalis; to screen their mechanisms of action by conducting the cell membrane permeability assay (CMP); and to determine the possible cytotoxicity of the three EOs against human neuroblastoma cells (SH-SY5Y).

METHODS AND RESULTS

The antifungal activity was tested against four phytopathogenic fungi (Monilinia fructicola, Aspergillus niger, Penicillium expansum and Botrytis cinerea). The antibacterial activity was evaluated against two Gram-positive (G+ve) (Bacillus megaterium and Clavibacter michiganensis) and three Gram-negative (G-ve) bacterial strains (Pseudomonas fluorescens, P. syringae pv. phaseolicola and Xanthomonas campestris). Results showed that the three tested EOs have antifungal activity against M. fructicola and P. expansum and effective antibacterial activity against P. syringae pv. phaseolicola and B. megaterium. Moreover, the three EOs were evaluated for their ability to inhibit the growth of SH-SY5Y cells with MTT assay. J. communis EO was the more effective with an IC₅₀ of 53·7 μg ml^-1 . The antioxidant capacity of the three EO did not differ as measured by the DPPH assay.

CONCLUSIONS

The three tested juniper EOs showed promising antimicrobial and antioxidant activity and cytotoxic effects against human neuroblastoma cell line.

SIGNIFICANCE AND IMPACT OF THE STUDY

The outfindings from this research showed promising antimicrobial effects of the three oils against the majority of the tested phytopathogens with a potential to utilize them as natural alternatives to synthetic drugs, the cause of global environmental problems, pathogen resistance and difficulty to control many post-harvest plant diseases.

Effects of different heat treatments on lysozyme quantity and antimicrobial activity of jenny milk

Thermal treatments are used to improve milk microbial safety, shelf life, and biological activity of some of its components. However, thermal treatments can reduce the nutritional quality of milk, affecting the molecular structure of milk proteins, such as lysozyme, which is a very important milk component due to its antimicrobial effect against gram-positive bacteria. Jenny milk is characterized by high lysozyme content. For this reason, in the last few years, it has been used as an antimicrobial additive in dairy products as an alternative to hen egg white lysozyme, which can cause allergic reactions. This study aimed to investigate the effect of pasteurization and condensation on the concentration and antimicrobial activity of lysozyme in jenny milk. Furthermore, lysozyme quantity and activity were tested in raw and pasteurized milk after condensation at 40 and 20% of the initial volume. Reversed-phase HPLC was performed under fluorescence detection to monitor lysozyme in milk samples. We evaluated the antimicrobial activity of the tested milk against Bacillus megaterium, Bacillus mojavensis, Clavibacter michiganensis, Clostridium tyrobutyricum, Xanthomonas campestris, and Escherichia coli. Condensation and pasteurization did not affect the concentration or antimicrobial activity of lysozyme in jenny milk, except for B. mojaventis, which showed resistance to lysozyme in milk samples subjected to heat treatments. Moreover, lysozyme in jenny milk showed antimicrobial activity similar to synthetic antibiotics versus some gram-positive strains and also versus the gram-negative strain X. campestris.