Biological and proteomic analysis of a new isolate of the nematophagous fungus lecanicillium sp.

BACKGROUND: In our continuing search for biologically active natural enemies from North of Africa with special reference to Tunisian fungi, our teamwork screened fungi from different ecological habitats in Tunisia. Our previous study on the comparative effectiveness of filamentous fungi in the biocontrol of Meloidogyne javanica, a taxon (Lecanicillium) showed high potentiality against M. javanica. We undertook the present study to evaluate the ability and understand the mechanism of this fungal parasite as a biological control candidate against the root-knot nematode M. javanica. This study used in vitro bioassays with fungal filtrate cultures, scanning electron microscopy (SEM) observation, and isobaric tag for relative and absolute quantitation (iTRAQ) methodology to characterize the biological and molecular features of this fungus. RESULTS: The microscopic and SEM observation revealed that Lecanicillium sp. exhibited exceptional hyperparasitism against M. javanica eggs. The hyphae of this fungi penetrated the eggs, causing destructive damage to the outer eggshell. The exposure to five concentrations of Lecanicillium sp. filtrate cultures showed high inhibition of egg hatching, which increases depending on the exposure time; the best results are recorded at 50%, 75%, and 100% dilutions after seven days of exposure. The SEM observation of nematode-parasitized eggs and juveniles suggests that the production of lytic enzymes degrades the egg cuticle and fungal hyphae penetrate unhatched M.javanica juveniles. Forty-seven unique proteins were identified from the Lecanicillium sp. isolate. These proteins have signalling and stress response functions, bioenergy, metabolism, and protein synthesis and degradation. CONCLUSION: Collectively, Lecanicillium sp. had ovicidal potentiality proved by SEM and proteomic analysis against root-knot nematode' eggs. This study recommended applying this biological control candidate as a bio-agent on vegetable crops grown in situ.

Comparative Effectiveness of Filamentous Fungi in Biocontrol of Meloidogyne javanica and Activated Defense Mechanisms on Tomato.

The nematicidal potential of five filamentous fungi as biological control agents (BCAs) against the root-knot nematode (RKN), Meloidogyne javanica, infecting tomato was assessed in vitro and in pot experiments. The five promising native taxa, namely Trichoderma longibrachiatum, T. harzainum, T. asperellum, Lecanicillium spp., and Metacordyceps chlamydosporia, were selected to compare their effectiveness against both chemical (Mocap, 10% ethoprophos) and biological (abamectin) nematicides on M. javanica reproduction indices and plant growth parameters. The stimulation of defense mechanisms was assessed by monitoring changes in the enzymatic activities of the polyphenol oxidase (PPO), peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT), lipid peroxidation (MDA), phenols, and proteins content of tomato roots. The laboratory assays revealed that T. longibrachiatum, M. chlamydoporia, and Lecanicillium spp. seemed to be the most effective under laboratory conditions, with more than 60% of juvenile mortality. The egg infection rate was above 62%, and the egg hatching rate was below 32%. The direct parasitism by the five taxa was confirmed by scanning electron microscope observation. The results of this study found a similar parasitism mechanism for T. longibrachiatum, T. harzianum, and M. chlamydosporia, where their hyphae and spores adhered to the M. javanica juveniles cuticle layer and formed trapping rings around them. The pot experiment results showed that T. harzianum and Lecanicillium spp. enhanced the plant growth parameters. Trichoderma longibrachiatum, abamectin, and the ethoprophos-based nematicides effectively decreased the reproduction rates of the nematode. The Trichoderma species and M. chlamydosporia significantly reduced the gall index and female fecundity of RKN. The treatment with BCAs and chemical nematicides involved a significant increase in the antioxidant activities of nematode-infected plants. The ethoprophos and fungal treatments decreased the MDA and total phenols content compared with the nematode-infested seedlings. This paper analyzes the advancements made towards the effective and efficient biocontrol of M. javanica using different fungal taxa, especially T. longibrachiatum and M. chlamydosporia, and the implications of these advancements for sustainable agriculture and food security.

Antibiotic sensitivity and resistance of gastrointestinal microflora isolated from preterm neonates.

Aim: This study aimed to isolate and identify common bacteria from 19 preterm neonates who spent their first weeks in the neonatal intensive care unit. Materials & methods: Stool samples were collected, and bacteria were isolated and purified from the samples. The isolated bacterial species were tested for antibiotic susceptibility or resistance. Results: Three common species were found in 15 stool samples: Enterobacter cloacae, Enterococcus fecalis and Klebsiella pneumoniae. Minimum inhibitory concentrations determined using antibiotic susceptibility testing showed that the minimum level of isolates was affected by the most commonly used antibiotics, with significant resistance to some of the tested antibiotics. Conclusion: The development of beneficial normal flora in preterm neonates plays a vital role in their health and well-being.

Tamarix arabica and Salvadora persica as antibacterial agents.

Despite the harsh conditions and limited water resources of the Arabian Peninsula, plants that live in this environment contain a variety of bioactive compounds and have been used in traditional medicines for thousands of years. We investigated the effects of ethanol extracts of Tamarix arabica and Salvadora persica on Gram-negative and Gram-positive bacteria. The investigations were include; the inhibition of the bacterial growth, determination of MIC and MBC, detection of kill-time, potassium and phosphorus leakages and detection of the bioactive compounds by the GC-MS analysis. The tested extracts in combination, at a 1:1 volume ratio, showed high inhibitory effects, as reflected by the minimum inhibitory concentrations and minimum bactericidal concentrations. The new EC plate was used to determined MBC and kill-time. Further, the detection of phosphate and potassium leakage indicated a loss of selective permeability of the cytoplasmic membrane after treatment with these extracts. The bioactive compounds in the ethanol extracts of T. arabica and S. persica may offer a less expensive and natural alternative to pharmaceuticals.