Species‐specific detection of Candida tropicalis using evolutionary conserved intein DNA sequences

Inteins (internal proteins) are self‐splicing transportable genetic elements present in conserved regions of housekeeping genes. The study highlights the importance of intein as a potential diagnostic marker for species‐specific identification of Candida tropicalis, a rapidly emerging opportunistic human pathogen. Initial steps of primer validation, sequence alignment, phylogenetic tree analysis, gel electrophoresis and real‐time polymerase chain reaction (PCR) assays were performed to confirm the specificity of the designed primers. The primers were selective for C. tropicalis with 100% inclusivity and showed no cross‐species or cross‐genera matches. The established technique is a prototype for developing multifaceted PCR assays and for point‐of‐care testing in near future.

Significance and Impact of the Study

Development of molecular markers for specific detection of microbial pathogens using real‐time polymerase chain reaction (PCR) is an appealing and challenging technique. A real‐time PCR is an emerging technology frequently used to detect the aetiologic agents. In recent times, designing species‐specific primers for pathogen detection is gaining momentum. The method offers rapid, accurate and cost‐effective strategy to identify the target, thus providing sufficient time to instigate appropriate chemotherapy. The study highlights the use of intein DNA sequence as molecular markers for species‐specific identification of Candida tropicalis. The study also offers a prototype model for developing multifaceted PCR assays using intein DNA sequences, and provides a developmental starting point for point‐of‐care testing in near future.     

Piper regnellii extract biopolymer‐based microparticles: production,characterization and antifungal activity

Aims

This study aims to improve characteristics of Piper regnellii extract to make it applicable in formulations to treat dermatophytosis, also known as ringworm.

Methods and Results

Microparticles (MPs) were produced by spray drying with gelatin, alginate and chitosan as encapsulating agents; characterized by scanning electron microscopy, encapsulation efficiency, thermal analyses and X‐ray diffraction; and tested against Trichophyton rubrum by broth microdilution. Produced MPs had a mean diameter less than 2 μm, an increase in stability and release of the extract and good results for encapsulation efficiency, being 85·6% to gelatin MP, 71·3% to chitosan MP and 60·6% to alginate. MPs preserved the antifungal activity of P. regnellii extract T. rubrum.

Conclusion

Microencapsulation provided a significant improvement in the stability of the P. regnellii extract and better solubilization of chemical compounds, maintaining the antifungal effect against T. rubrum.

Significance and Impact of the Study

These results are useful for developing a formulation to treat fungal infections caused by dermatophyte species.     

Greek indigenous streptomycetes as biocontrol agents against the soil‐borne fungal plant pathogen Rhizoctonia solani

Aims

To examine the biocontrol potential of multiactive Greek indigenous Streptomyces isolates carrying antifungal activity against Rhizoctonia solani that causes damping‐off symptoms on beans.

Methods and Results

A total of 605 Streptomyces isolates originated from 12 diverse Greek habitats were screened for antifungal activity against R. solani DSM843. Almost one‐third of the isolates proved to be antagonistic against the fungus. From the above isolates, six were selected due to their higher antifungal activity, identified by analysing their 16S rRNA gene sequence and studied further. The obtained data showed the following: firstly, the isolates ACTA1383 and ACTA1557 exhibited the highest antagonistic activity, and therefore, they were selected for in vivo experiments using bean seeds as target; secondly, in solid and liquid culture experiments under optimum antagonistic conditions, the medium extracts from the isolates OL80, ACTA1523, ACTA1551 and ACTA1522 suppressed the growth of the fungal mycelium, while extracts from ACTA 1383 and ACTA1557 did not show any activity.

Conclusions

These results corresponded important indications for the utility of two Greek indigenous Streptomyces isolates (ACTA1557 and ACTA1383) for the protection of the bean crops from R. solani damping‐off symptoms, while four of them (isolates OL80, ACTA1523, ACTA1551 and ACTA1522) seem to be promising producers of antifungal metabolites.

Significance and Impact of the Study

This is the first study on the biocontrol of R. solani using multiactive Streptomyces isolates originated from ecophysiologically special Greek habitats. Our study provides basic information to further explore managing strategies to control this critical disease.