Identification of epiphytic bacterial communities associated with the brown alga Splachnidium rugosum

Abstract

Marine macroalgae host diverse bacterial communities with which they share a complex array of chemical interactions based on the exchange of nutrients, minerals and secondary metabolites. The brown alga Splachnidium rugosum is a rich source of a valuable fucose-containing sulphated polysaccharide (fucoidan). It grows exclusively in the Southern Hemisphere along temperate shores. While growth and development are dependent on specific microbial interactions, the microbiome of S. rugosum has not been characterized. This study reports on the composition and uniqueness of epiphytic bacterial communities associated with S. rugosum. Sporophytes were collected during winter (July 2012) from the Western Cape (−34°18′ 5.0004″, +18°48′ 59.0004″), South Africa. Culture-based methods relied on a range of selective marine media including marine agar, nutrient sea water agar, nutrient agar and thiosulfatecitrate-bile-salts-sucrose agar. Epiphytic isolates were identified to species level by 16S rRNA gene sequence analysis and encompassed 39 Gram-negative and 2 Gram-positive bacteria. Isolates were classified as Gamma-Proteobacteria, AlphaProteobacteria, Firmicutes or Bacteriodetes. GammaProteobacteria were the most abundant, dominated by Vibrio and Pseudoalteromonas species. Three isolates displayed low sequence identity ( 97 %) with their closest relatives and were grouped into the genera Shewanella, Sphingomonas and Sulfitobacter. All bacterial isolates (41) were screened for antimicrobial activity against indicator strains of Bacillus cereus, Staphylococcus epidermidis, Mycobacterium smegmatis, Micrococcus luteus and Pseudomonas putida. Fifteen isolates (36 %) displayed antimicrobial activity against one or more of the indicator strains. One isolate (Pseudomonas sp.) was active against all strains tested. Splachnidium rugosum is a valuable source for the discovery of bioactive compounds of bacterial origin active against human pathogens.

Antimicrobial Activities of Bacteria Associated with the Brown Alga Padina pavonica

“…After characterization, Gram-negative Alpha - and Gammaproteobacteria and Gram-positive Firmicutes and Actinobacteria were identified from P. pavonica . Most of the isolates belonged to Gram-negative bacteria, as was the case for epibionts of seaweeds (Lakshmanaperumalsamy and Purushothaman, 1982 ; Albakosh et al, 2016 ). Among the different P. pavonica isolates, isolates related to the genera Paracoccus, Acinetobacter , and Staphylococcus were reported in previous studies isolated from marine environments and seaweeds (Gallardo et al, 2004 ; Schulze et al, 2006 ; Li, 2009 ; Zeng et al, 2010 ).…”

“…In other previous study by Albakosh et al ( 2016 ) on the brown alga Splachnidium rugosum , a number of 41 isolates were obtained using 4 different medium; MA, nutrient sea water agar, nutrient agar and thiosulfate-citrate-bile-salts-sucrose agar. In this same study by Albakosh et al ( 2016 ), initially 29 isolates were obtained on MA medium and after identification, the number was narrowed down to 22 unique isolates. From our results and these previous work and observations it seems that MA is a suitable medium to isolates algal epiphytic bacteria as compared to other medium.…”

Marine macroalgae-associated heterotrophic Firmicutes and Gamma-proteobacteria: prospective anti-infective agents against multidrug resistant pathogens

“…Marine macroalgae and their symbiotic bacterial communities are potential sources in the field of biotechnology as a result of their production of a wide diversity of metabolites with wide range of bioactivities (Zubia et al 2009;Le Lann et al 2016). Microbes with inhibitory traits were found to reside symbiotically on the surface of marine macroalgae, providing it with a microorganism-mediated defence community (Kumar et al 2011;Penesyan et al 2009;Albakosh et al 2016;Xiong et al 2018). The interest in bacterial populaces living in relationship with marine macroalgae has expanded amid the recent decades to control food-borne pathogens as a result of the rise of antibiotic-resistant bacteria, and the need for new antimicrobial compounds.…”

A novel screening method for the detection of Pseudoalteromonas shioyasakiensis, an emerging opportunistic pathogen that caused the mass mortality of juvenile Pacific abalone (Haliotis discus hannai) during a record-breaking heat wave

“…Species of Pseudoalteromonas , one of the most common bacterial genera in the marine environment, generally act as probiotics in coral (Moree et al, 2014;Muchlissin, Sabdono, & Permata, 2018;Rosado et al, 2019;Sabdono, Sawonua, Kartika, Amelia, & Radjasa, 2015;Shnit-Orland, Sivan, & Kushmaro, 2012), abalone (Offret, Jegou, Mounier, Fleury, & Le Chevalier, 2019;Offret, Rochard, et al, 2019), marine bivalves (Desriac et al, 2014;Rodrigues, Paillard, Dufour, & Bazire, 2015;Sun et al, 2016) shrimp (Amoah et al, 2019;Pham et al, 2014), lobster (Goulden, Hall, Pereg, Baillie, & Hoj, 2013), sea cucumbers (Chi et al, 2014;Zheng et al, 2012), fish (Mladineo et al, 2016;Sayes, Leyton, & Riquelme, 2016;Verner-Jeffreys, Shields, Bricknell, & Birkbeck, 2004), marine algae (Albakosh, Naidoo, Kirby, & Bauer, 2016;Nagel et al, 2012), and sea stars (Lloyd & Pespeni, 2018). Only a few reports have identifiedPseudoalteromonas species as pathogenic to marine organisms, including fish (Nelson & Ghiorse, 1999;Pujalte, Sitja-Bobadilla, Macian, Alvarez-Pellitero, & Garay, 2007), crabs (Talpur et al, 2011), algae (Goecke, Labes, Wiese, & Imhoff, 2013;Schroeder, Jaffer, & Coyne, 2003), and sea cucumbers (Liu et al, 2010).…”