Effect of green alga Planktochlorella nurekis on selected bacteria revealed antibacterial activity in vitro

Abstract

ABSTRACT:The green alga Planktochlorella nurekis (Chlorellaceae, Chlorophyta) is considered a producer of antibacterial mixture of long-chain fatty acids, which has possibly similar composition and mode of action as chlorellin produced by another green alga, Chlorella vulgaris. Although the antibacterial properties of C. vulgaris have been reported, the interactions of P. nurekis with bacteria have not been determined yet. The aim of this study was to elucidate the effect of P. nurekis water suspension on growth of selected gastrointestinal bacteria in vitro so that it could be used as a suitable feed supplement in animal farming. Unknown bacterial populations occurring in the algal suspension were identified using 16S rRNA sequencing assay. Selected strains were cultivated with lyophilized P. nurekis and the antibacterial effect was monitored. The composition of fatty acids and heat sensitivity of antibacterial substances were also examined. Sequencing analysis of 71 bacterial 16S rRNA genes in xenic algal suspension identified common environmental microbiota, one strain belonging to the class Alphaproteobacteria, 17 to Betaproteobacteria, 44 to Gammaproteobacteria (dominated by Pseudomonas putida strains), and nine to Sphingobacteria. The antimicrobial activity of P. nurekis suspension was tested at a concentration range of 0.75-6 mg/ml. The highest inhibitory effect was observed on bifidobacteria. Statistically significant reductions in bacterial counts were also observed for Escherichia coli, Salmonella enterica var. Enteritidis, S. enterica var. Infantis, Campylobacter jejuni, and Arcobacter butzleri. The growth of Lactobacillus johnsonii was significantly stimulated. The relative proportions of C14-C22 fatty acids in P. nurekis were found as follows: saturated 54.28%, monounsaturated 30.40%, and polyunsaturated 7.16%. The antibacterial compounds present in P. nurekis suspension exhibited thermostability. The results indicate that P. nurekis can inhibit some pathogenic gastrointestinal bacteria and seems to be a promising essential nutrients source in animal nutrition.

Application of Green Algal Planktochlorella nurekis Biomasses to Modulate Growth of Selected Microbial Species

“…The fatty acid concentrations obtained in the study by Cermak L. et al (2015) on P. nurekis biomass are significantly lower than in the case of biomass obtained from polyploid clones P. nurekis subject of our analyses. These differences concern the content of myristic acid whose content in P. nurekis biomass is estimated at 1.74%, palmitic acid at 26.91% and linoleic acid (omega 6) at 4.13% [ 4 ]. In the case of biomasses obtained from polyploid clones, the content of these acids increases significantly to 5.1%, 61.1% and 31.2%, respectively (characteristics of the FA profile of biomasses are described in an earlier paper [ 15 ]).…”

“…In the case of biomasses obtained from polyploid clones, the content of these acids increases significantly to 5.1%, 61.1% and 31.2%, respectively (characteristics of the FA profile of biomasses are described in an earlier paper [ 15 ]). Additionally, the inhibitory activity of biomass on the growth of microorganisms in the work of Cermak L. et al (2015) [ 4 ] was demonstrated at higher concentrations, i.e., 6 mg·mL −1 observed against Escherichia coli , Salmonella enterica var. infantis K2 .…”

“…This is important because microalgae have evolved in extremely competitive environments and have had to develop different tolerance and defense strategies against pathogenic microorganisms, predation, herbivory and competition for space in order to survive. The variety of defense mechanisms results in microalgae producing a large pool of diverse biologically active compounds synthesized from different metabolic pathways [ 3 , 4 ]. Moreover, it is indicated that the diversity of microalgae cellular building blocks, mainly cell wall components (polysaccharides, lipids, proteins), whose amount depends on the ecotypes of a given species developing in specific environmental conditions, may affect the biological activity of biomasses obtained from algal cultures.…”

“…There are literature data indicating the specific antimicrobial properties of individual algal species. Here we should mention the best-studied microalgae species Chlorella vulgaris , which shows the ability to produce chlorelin, a mixture of fatty acids (FAs) inhibiting the growth of G (+) and G (−) bacteria [ 4 , 8 ]. Moreover, the biomass of other algal species, such as Chlamydomonas reinwardti , Chroococcus dispersus , Spirulina platensis , Chlorella pyrenoidos , Dunaliella sp., Cenedesmus obliquus and Nostoc muscorum , exhibit not only antibacterial, antiviral and antifungal, but also antioxidant, anticancer, anti-inflammatory and anti-allergic activities [ 9 , 10 , 11 , 12 , 13 , 14 ].…”

Antibacterial Derivatives of Marine Algae: An Overview of Pharmacological Mechanisms and Applications

“…The cell walls of both bacteria were perforated, resulting in rupture of the cell wall, cytoplasmic leakage, shrinking of the protoplasm, cytoplasmic vacuolation, scattering of chromatin, distortion of the outer cell shape, and decreased cell size. Čermák et al [ 44 ] reported the antibacterial long-chain fatty acids in the green microalga Planktochlorella nurekis to be significant inhibitors of Campylobacter jejuni , Escherichia coli , Salmonella enterica var. Enteritidis , Salmonella enterica var.…”