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The discovery of mid‐Proterozoic (1.8–0.8 billion years ago, Ga) indigenous biomarkers is a challenge, since biologically informative molecules of such antiquity are commonly destroyed by metamorphism or overprinted by drilling fluids and other anthropogenic petroleum products. Previously, the oldest clearly indigenous biomarkers were reported from the 1.64 Ga Barney Creek Formation in the northern Australian McArthur Basin. In this study, we present the discovery of biomarker molecules from carbonaceous shales of the 1.73 Ga Wollogorang Formation in the southern McArthur Basin, extending the biomarker record back in time by ~90 million years. The extracted hydrocarbons illustrate typical mid‐Proterozoic signatures with a large unresolved complex mixture, high methyl alkane/n‐alkane ratios and the absence of eukaryotic steranes. Acyclic isoprenoids, saturated carotenoid derivatives, bacterial hopanes and aromatic hopanoids and steroids also were below detection limits. However, continuous homologous series of low molecular weight C14–C19 2,3,4‐ and 2,3,6‐trimethyl aryl isoprenoids (AI) were identified, and C20–C22 AI homologues were tentatively identified. Based on elevated abundances relative to abiogenic isomers, we interpret the 2,3,6‐AI isomer series as biogenic molecules and the 2,3,4‐AI series as possibly biogenic. The biological sources for the 2,3,6‐AI series include carotenoids of cyanobacteria and/or green sulphur bacteria (Chlorobiaceae). The lower concentrated 2,3,4‐AI series may be derived from purple sulphur bacteria (Chromatiaceae). These degradation products of carotenoids are the oldest known clearly indigenous molecules of likely biogenic origin. [ABSTRACT FROM AUTHOR]

The safeguarding of Australian outdoor stone heritage is currently limited by a lack of information concerning mechanisms responsible for the degradation of the built heritage. In this study, the bacterial community colonizing the stone surface of an outdoor sculpture located at the Church of St. John the Evangelist in Melbourne was analysed, providing an overview of the patterns of microbial composition associated with stone in an anthropogenic context. Illumina MiSeq 16S rRNA gene sequencing together with confocal laser microscope investigations highlighted the bacterial community was composed of both phototrophic and chemotrophic microorganisms characteristic of stone and soil, and typical of arid, salty and urban environments. Cardinal exposure, position and surface geometry were the most important factors in determining the structure of the microbial community. The North-West exposed areas on the top of the sculpture with high light exposure gave back the highest number of sequences and were dominated by Cyanobacteria. The South and West facing in middle and lower parts of the sculpture received significantly lower levels of radiation and were dominated by Actinobacteria. Proteobacteria were observed as widespread on the sculpture. This pioneer research provided an in-depth investigation of the microbial community structure on a deteriorated artistic stone in the Australian continent and provides information for the identification of deterioration-associated microorganisms and/or bacteria beneficial for stone preservation. • A pioneer study of biofilm on stone heritage in Australia. • Structure, diversity and interactions of biofilms on the outdoor stones was studied. • Community was composed of both phototrophic and chemotrophic bacteria. • Proteobacteria, Actinobacteria and Cyanobacteria were dominant phyla. • Bacterial community was shaped by cardinal exposure, position and surface geometry. [ABSTRACT FROM AUTHOR]

Aerobic Anoxygenic Phototrophic Bacteria (AAnPB) are ecologically important microorganisms, widespread in oceanic photic zones. However, the key environmental drivers underpinning AAnPB abundance and diversity are still largely undefined. The temporal patterns in AAnPB dynamics at three oceanographic reference stations spanning at approximately 15° latitude along the Australian east coast were examined. AAnPB abundance was highly variable, with pufM gene copies ranging from 1.1 × 102 to 1.4 × 105 ml−1 and positively correlated with day length and solar radiation. pufM gene Miseq sequencing revealed that the majority of sequences were closely related to those obtained previously, suggesting that key AAnPB groups are widely distributed across similar environments globally. Temperature was a major structuring factor for AAnPB assemblages across large spatial scales, correlating positively with richness and Gammaproteobacteria (phylogroup K) abundance but negatively with Roseobacter-clade (phylogroup E) abundance, with temperatures between 16°C and 18°C identified as a potential transition zone between these groups. Network analysis revealed that discrete AAnPB populations exploit specific niches defined by varying temperature, light and nutrient conditions in the Tasman Sea system, with evidence for both niche sharing and partitioning amongst closely related operational taxonomic units. [ABSTRACT FROM AUTHOR]

The article presents a study that deals with the association between the photosynthetic endosymbionts and scleractinian corals inhabiting deep reef ecological systems. It assesses the deep-water Symbiodinium diversity from 10 different coral genera at a depth range of 45 to 70 meters on the Great Barrier Reef in Australia. It employs denaturing ingredient gel electrophoresis fingerprinting of the internal transcribed spacer region of the ribosomal DNA to establish Symbiodinium identity. It stresses the need to examine symbiont diversity across broad environmental ranges.

The development and demise of substantial populations of bacteriochlorophyll (BChl) a and d containing phototrophs are documented within the bottom waters of a billabong (oxbow lake) in south-eastern Australia. The observation of such populations within a freshwater body is unusual, illustrating an unexpected source of organic carbon within the floodplain ecosystem of one of Australia's principal rivers. Values of up to 1086 µg L−1 BChl a and 490 µg L−1 BChl d were recorded during an 11 month study of physico-chemical parameters, algae and bacteria. An unusual density stratification was observed within the billabong, fostered by an increase in bivalent ions at depth, and leading to persistent anoxia below 0.75 m depth over summer. A marked vertical distribution was observed for both algae and bacteria, that for the bacteria being lost with a mixing event in late March. The presence of up to 74 µg L−1 BChl a at the surface of the billabong during the summer months is ascribed to entrainment of bacteria within bubble plumes rising from the sediments. [ABSTRACT FROM AUTHOR]

. Populations of foliose dictyoccratid sponges were surveyed on the forc-rccf (windward) slopes of reefs across the central and northern sections of the Great Barrier Reef. Foliose sponges constitute more than 50 % of invidual abundance on clean water reefs and more than 80 % on some of these reefs. These sponges arc generally small and occur in greatest abundance on the slopes between 10 and 30 m depth, forming more than 20% of the total sponge biomass. Species of the genera Phyllospongia and Carteriospongia were most prevalent, particularly the species P. lamel-losa, C. flabellifera, C.foliascens, and an unidentified thorcctid. The majority of these foliose sponges have a predominantly phototrophic nutrition with more than 50% of carbon energy being derived from the photosynthetic activities of cyanobactcrial symbionts. The foliose dictyoccratids were absent from inner-shelf reefs, which feature higher sediment loads and concentrations of organic nutrients. [ABSTRACT FROM AUTHOR]