Screening and Transcriptional Analysis of Polyketide Synthases and Non-ribosomal Peptide Synthetases in Bacterial Strains From Krubera-Voronja Cave

Dominykas Bukelskis; Daiva Dabkeviciene; Laima Lukoseviciute; Airidas Bucelis; Ignas Kriaučiūnas; Jolanta Lebedeva; Nomeda Kuisiene

doi:10.3389/fmicb.2019.02149

Screening and Transcriptional Analysis of Polyketide Synthases and Non-ribosomal Peptide Synthetases in Bacterial Strains From Krubera-Voronja Cave

Front Microbiol. 2019 Sep 13:10:2149. doi: 10.3389/fmicb.2019.02149. eCollection 2019.

Authors

Dominykas Bukelskis¹, Daiva Dabkeviciene², Laima Lukoseviciute¹, Airidas Bucelis¹, Ignas Kriaučiūnas¹, Jolanta Lebedeva¹, Nomeda Kuisiene¹

Affiliations

¹ Institute of Biosciences, Department of Microbiology and Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania.
² Institute of Biosciences, Department of Biochemistry and Molecular Biology, Life Sciences Center, Vilnius University, Vilnius, Lithuania.

Abstract

Identification of novel bioactive compounds represents an important field in modern biomedical research. Microorganisms of the underexplored environments, such as deserts, hot springs, oceans, and caves are highly promising candidates for screening such metabolites. Screening for biosynthetic genes is the most effective strategy to characterize bioactivity in a certain environment. However, knowledge is either scant or non-existent about the expression of the biosynthetic genes encoding for various bioactive compounds in the microorganisms from the caves. The aim of the current study was to screen for the genes of polyketide synthases and non-ribosomal peptide synthetases in Krubera-Voronja Cave (43.4184 N 40.3083 E, Western Caucasus) bacterial isolates as well as to evaluate the expression of these genes under laboratory conditions. In total, 91 bacterial strains isolated from the cave were screened for the presence of polyketide synthase and non-ribosomal peptide synthetase genes. Phenotypically inactive strains were the main focus (the test group) of our study, while the strains with the identified antibacterial activity served as the control group. Our PCR-based screening clearly showed that the majority of the strains harbored at least one biosynthetic gene. Prediction of the putative products allowed us to identify bioactive compounds with antibacterial, anticancer, antifungal, anti-inflammatory, antimycoplasmic, antiviral, insecticidal, and thrombolytic activity. For most polyketide synthases and non-ribosomal peptide synthetases, putative products could not be predicted; they are unknown. Qualitative transcriptional analysis did not show substantial differences between the test group and the control group of the strains. One to four biosynthetic genes were constitutively expressed in all the tested strains, irrespective of the group. Quantitative transcriptional analysis of the constitutively expressed biosynthetic genes demonstrated that the expression of a particular gene could be affected by both the amount of the nutrients in the culture medium and the growth phase.

Keywords: Krubera–Voronja Cave; RT-qPCR; non-ribosomal peptide synthetase; polyketide synthase; transcriptional.