The authors regret the following line: "The South African coastline is characterized by high biodiversity [17] which has been largely untapped, primarily because of the large number of pristine marine protected areas (MPA)." The authors would like to replace this with the following sentence: "The South African coastline is characterized by high biodiversity [17] which has been largely untapped."The authors would like to apologise for any inconvenience caused.
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.
Microbial biotechnological processes can be based on single species pure cultures or on multi-species assemblages. While these assemblages can be advantageous by offering more functionalities and more resilience to changing environmental conditions, they can be unpredictable and difficult to control under synthetically engineered growth conditions. To overcome the unpredictable nature of these microbial assemblages, the generation of stable mutualistic systems through synthetic ecology approaches may provide novel solutions for understanding microbial interactions in these environments. Here we establish a stable association between two evolutionarily unrelated, but biotechnologically complementary species isolated from winery wastewater; a strain of the yeast Saccharomyces cerevisiae and microalga, Chlorella sorokiniana . Yeast and microalgae were able to form obligate (interdependent) and non-obligate (facultative) mutualisms under engineered batch co-culture growth conditions. Obligate mutualism was maintained through the reciprocal exchange of carbon and nitrogen where the yeast ferments mannose to produce carbon dioxide for use by the microalga; and the microalga provides the yeast with nitrogen by metabolizing nitrite to ammonium. The effect of temperature and pH on the establishment of these mutualisms was evaluated and pH was found to be a key determinant for mutualism formation under obligatory conditions. Moreover, the combinations of the two species under non-obligatory growth conditions led to improvement in growth rate and biomass production when compared to single species cultures grown under the same conditions. Such engineered mutualisms are the first step in developing stable multi-species assemblages, while providing a system to generate novel insight into the evolution of mutualistic interactions between phylogenetically distant microorganisms.
Inorganic nitrogen has been identified as the major growth-limiting nutritional factor affecting Gracilaria gracilis populations in South Africa. Although the physiological mechanisms implemented by G. gracilis for adaption to low nitrogen environments have been investigated, little is known about the molecular mechanisms of these adaptions. This study provides the first investigation of G. gracilis proteome changes in response to nitrogen limitation and subsequent recovery. A differential proteomics approach employing two-dimensional gel electrophoresis and liquid chromatography-tandem mass spectrometry was used to investigate G. gracilis proteome changes in response to nitrogen limitation and recovery. The putative identity of 22 proteins that changed significantly (P < 0.05) in abundance in response to nitrogen limitation and recovery was determined. The identified proteins function in a range of biological processes including glycolysis, photosynthesis, ATP synthesis, galactose metabolism, protein-refolding and biosynthesis, nitrogen metabolism and cytoskeleton remodeling. The identity of fructose 1,6 biphosphate (FBP) aldolase was confirmed by western blot analysis and the decreased abundance of FBP aldolase observed with two-dimensional gel electrophoresis was validated by enzyme assays and western blots. The identification of key proteins and pathways involved in the G. gracilis nitrogen stress response provide a better understanding of G. gracilis proteome responses to varying degrees of nitrogen limitation and is the first step in the identification of biomarkers for monitoring the nitrogen status of cultivated G. gracilis populations.
Yeast and microalgae are microorganisms with widely diverging physiological and biotechnological properties. Accordingly, their fields of applications diverge: yeasts are primarily applied in processes related to fermentation, while microalgae are used for the production of high-value metabolites and green technologies such as carbon capture. Heterotrophic–autotrophic systems and synthetic ecology approaches have been proposed as tools to achieve stable combinations of such evolutionarily unrelated species. We describe an entirely novel synthetic ecology-based approach to evolve co-operative behaviour between winery wastewater isolates of the yeast Saccharomyces cerevisiae and microalga Chlorella sorokiniana. The data show that biomass production and mutualistic growth improved when co-evolved yeast and microalgae strains were paired together. Combinations of co-evolved strains displayed a range of phenotypes, including differences in amino acid profiles. Taken together, the results demonstrate that biotic selection pressures can lead to improved mutualistic growth phenotypes over relatively short time periods.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.