A Novel Genetic Determination of a Lectin Gene in Iraqi Acinetobacter baumannii Isolates and Use of Purified Lectin as an Antibiofilm Agent.

BACKGROUND: Lectin was initially called hemagglutinin or agglutinin because of its capacity to agglutinate human as well as human erythrocytes. They are a heterogeneous group of proteins or glycoproteins of nonimmune origin. Because of their chemical properties, they have become a useful tool in several fields such as immunology, cell biology, molecular biology, membrane structure, pharmacology, cancer research, clinical chemistry, and genetic engineering.

OBJECTIVE: The wide applications of lectins users urged the need to isolate lectins from a new strain of bacteria can produce new and high yield of lectin because the current production of lectin from Pseudomonas spp. is very expensive. The goal of this study was to screen the ability of Acinetobacter baumannii isolates to produce lectin and detection of its phenotypic and genotypic profiles and detection of lectin ability to inhibit ofbiofilm formation.

METHODS: Fifty-one isolates from different sources were collected and detected genetically by using the recA gene. Phenotypic detection of lectin by using semi-quantitative analysis and quantitative analysis in microtiter plate. Genotypic detection of lectin by designed lec gene and used PCR technique. The lectin was extracted by using glass beads and purified by chromatographyic technique followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for determination the molecular size of lectin and finally detection the spectrum of biofilm inhibition by the purified lectin toward biofilm producers.

RESULTS: Of 51 A. baumannii isolates, 17 (33.3%) have been found to produce lectin. Ten of 17 were sequenced, of which 2 were submitted and tested by the gene bank National Center for Biotechnology Information (NCBI), and accession numbers (KX766405.1 and KX766406.1) were obtained. These 17 isolates were phenotypically and genotypically positive for lectin and showed different lec gene expression in semi-quantitative and quantitative analysis. The activities ranged between 4-128 U/mL. Lectin purified by ammonium sulfate precipitation was used to inhibit biofilm formation. We found reduction at three different types of bacteria ranging from 26% for Klebsiella pneumonia, 46.7% for P. stutzeri and 53% for A. baumannii. These results suggested that lectin has a promising application as an antibiofilm agent to combat the growing number of multidrug-resistant pathogen-associated infections.

CONCLUSIONS: Lectin has been detected recently in A. baumannii, but the genetic property of this lectin has not yet been fully studied. In our study, we determined the presence of the lectin gene (lec gene) in A. baumannii by using PCR technique, and lec PCR products were identified with various source of isolation and sequenced to screening for epidemiology and submitted to the gene bank NCBI under accession number (KX766405.1 and KX766406.1).

HIGHLIGHTS: A. baumannii has an ability to produce lectin protein; Lec gene was detected in A. baumannii, and the sequence was recorded under accession number KX766405.1 and KX766406.1.; Lectin was extracted by glass beads and purified by chromatographyic technique; Lectin had strong effect against biofilm formation.