Diverse hypolithic refuge communities in the McMurdo Dry Valleys

Hyper-arid deserts present extreme challenges to life. The environmental buffering provided by quartz and other translucent rocks allows hypolithic microbial communities to develop on sub-soil surfaces of such rocks. These refuge communities have been reported, for many locations worldwide, to be predominantly cyanobacterial in nature. Here we report the discovery in Antarctica’s hyper-arid McMurdo Dry Valleys of three clearly distinguishable types of hypolithic community. Based on gross colonization morphology and identification of dominant taxa, we have classified hypolithic communities as Type I (cyanobacterial dominated), Type II (fungal dominated) and Type III (moss dominated). This discovery supports a growing awareness of the high biocomplexity in Antarctic deserts, emphasizes the possible importance of cryptic microbial communities in nutrient cycling and provides evidence for possible successional community processes within a cold arid landscape

Characterisation of microbial communities associated with hypolithic environments in Antarctic Dry Valley soils

Philosophiae Doctor - PhDThe Eastern Antarctic Dry Valley region is a polar desert, where conditions of extreme aridity, high temperature fluctuations and high irradiation levels make it one of the most extreme environments on earth. Despite the harsh environment, the soils in this region yield a wide range of bacterial and eukaryotic phylotypes in greater abundance than previously believed. In the Dry Valleys, highly localized niche communities colonise the underside of translucent quartz rocks and present macroscopic growth.South Afric

Increasing the scale of peroxidase production by Streptomyces sp. strain BSII#1

AIMS : To optimise peroxidase production by Streptomyces sp. strain BSII#1, up to 3 l culture volumes. METHODS AND RESULTS : Peroxidase production by Streptomyces sp. strain BSII#1 was optimised in terms of production temperature and pH and the use of lignin-based model chemical inducers. The highest peroxidase activity (1.30±0.04 U ml-1) in 10 ml culture volume was achieved in a complex production medium (pH 8) at 37°C in the presence of 0.1 mmol l-1 veratryl alcohol, which was greater than those reported previously. Scale-up to 100 ml and 400 ml culture volumes resulted in decreased peroxidase production (0.53±0.10 U ml- 1 and 0.26±0.08 U ml-1 respectively). However, increased aeration improved peroxidase production with the highest production achieved using an airlift bioreactor (4.76±0.46 U ml-1 in 3 l culture volume). CONCLUSIONS : Veratryl alcohol (0.1 mmol l-1) is an effective inducer of peroxidase production by Streptomyces sp. strain BSII#1. However, improved aeration increased peroxidase production in larger volumes without the use of an inducer, surpassing induced yields in an optimised small-scale process. SIGNIFICANCE AND IMPACT OF THE STUDY : Only a limited number of reports in literature have focused on the up-scaling of bacterial peroxidase production. There remains opportunity for feasible large-scale production of bacterial peroxidases with potentially novel biocatalytic properties.National Research Foundation (NRF) of South Africa,Water Research Commission.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2672hb201

The development of the emerging technologies sustainability assessment (ETSA) and its application in the design of a bioprocess for the treatment of wine distillery effluent

Emerging Technologies Sustainability Assessment (ETSA) is a new technology assessment tool that was developed in order to compare emerging processes or technologies to existing alternatives. It utilizes infoIDlation modules, with the minimum use of resources such as time and money, in order to deteIDline if the process under development is comparatively favourable and should be developed beyond the early conceptual phase. The preliminary ETSA is vital in order to identify the gaps in the existing information and the specific methodologies to be used for data capture and analysis. The use of experimental design tools, such as Design-Expert, can facilitate rapid and efficient collection of necessary data and fits in well with the rationale for the ETSA. Wine distillery effluent (vinasse) is the residue left after alcohol has been distilled from fennented grape juice. It is an acidic, darkly coloured effluent, with a high COD and polyphenol content. The most popular method of disposal of this effluent, land application, is no longer viable due to stricter legislation and pressure on the industry to better manage its wastes. Although the ability of whiterot fungi to degrade a number of pollutants is well-known, fungal treatment of wine distillery effluent is still in the conceptual phase. The perfoIDlance of the fungal remediation system was assessed experimentally in terms of COD removal and laccase production using Design-Expert. Although Pycnoporus sanguine us was found to be most efficient at COD removal (85%) from 30% vinasse, laccase production was low (0.021 U/I). The optimum design for economically viable fungal treatment used Trametespubescens. This fungus was able to remove over 50% of the COD from undiluted vinasse while producing almost 800U/l of the valuable laccase enzyme within three days. Since the effluent from the fungal system did not meet the legal limits for wastewater disposal, a two-stage aerobicanaerobic system is suggested to improve the quality of the effluent prior to disposal. The ETSA was used to assess the fungal technology in relation to the two current methods of vinasse treatment and disposal, namely land application and anaerobic digestion. Based on the ETSA, which considered environmental, social and economic impacts, the fungal system proved to be potentially competitive and further development of the technology is suggested

The effect of biogenic and chemically manufactured silver nanoparticles on the benthic bacterial communities in river sediments

This study was conducted to determine and compare the effect of chemically-synthesised and biogenic silver nanoparticles on the benthic bacterial community structure in mesocosms containing sediment fromthree rivers in geographical sites with different population densities (low, medium, high), and therefore likely to be associated with respective low, moderate and high degrees of anthropogenic input. The nanoparticles were applied at the upper limit expected to accumulate in impacted environments (4 μg kgsed −1). The biomass, concentrations of elements, including selection metals (P, K, Na, K, Ca, Mg, Zn, Cu, Al, Ag) were all significantly higher at the high density than at the low density sites. Bacterial community profiling (terminal restriction fragment length polymorphismand amplicon sequencing) showed that the bacterial community structure in the sediments from the high population density site were resilient to environmental perturbations [adjustment from in-situ to ex-situ (laboratory) conditions], as well as to exposure to silver nanoparticles, with the converse being true for the lowpopulation density site. Results obtained fromamplicon sequencing were interrogated to the lowest taxonomic level with a relative abundance N5%. Proteobacteria was the most abundant phylum in all the sediments. Notable resistance (increased relative abundance) to one or both forms of silver nanoparticles was seen in the class Thermoleophilia, and the orders Myxococcales, Bacteriodales, Pirellules CCU21 and iii 1–15 (class Acidobacteria 6). Conversely, sensitivity was demonstrated in the family Koribacteraceae and the orders Rhizobiales, Ellin 329 and Gemmatales. It is recommended that pro-active environmental monitoring is performed in aquatic systems receiving point source pollution from wastewater treatment plants in order to assess the accumulation of silver nanoparticles. If necessary, measures should be implemented to mitigate the entry of silver nanoparticles, especially into more vulnerable environments

Hypolithic microbial communities of quartz rocks from Miers Valley, McMurdo Dry Valleys, Antarctica

The McMurdo Dry Valleys region of eastern Antarctica is a cold desert that presents extreme challenges to life. Hypolithic microbial colonisation of the subsoil surfaces of translucent quartz rocks represent a significant source of terrestrial biomass and productivity in this region. Previous studies have described hypoliths as dominated by cyanobacteria. However, hypoliths that occur in the lower Dry Valleys such as the Miers, Garwood and Marshall Valleys are unusual as they are not necessarily cyanobacteria-dominated. These hypoliths support significant eukaryal colonisation by fungi and mosses in addition to cyanobacteria- dominated bacterial assemblages and so have considerable ecological value in this barren landscape. Here, we characterise these novel hypoliths by analysis of environmental rRNA gene sequences. The hypolithic community was demonstrated to be distinct from the surrounding soil and non-translucent rocks. Hypoliths supported cyanobacterial signatures from the Oscillatoriales and Nostocales. Other heterotrophic bacterial signatures were also recovered, and these were phylogenetically diverse and spanned 8 other bacterial phyla. Archaeal phylotypes recovered were phylogenetically aYliated with the large group of unclassified, uncultured Crenarcheota. Eukaryal phylotypes indicated that free-living ascomycetous fungi, chlorophytes and mosses (Bryum sp.) were all supported by these hypoliths, and these are thought to be responsible for the extensive eukaryotic biomass that develops around quartz rocks

Production and characterisation of a novel actinobacterial DyP-type peroxidase and its application in coupling of phenolic monomers

The extracellular peroxidase from Streptomyces albidoflavus BSII#1 was purified to near homogeneity using sequential steps of acid and acetone precipitation, followed by ultrafiltration. The purified peroxidase was characterised and tested for the ability to catalyse coupling reactions between selected phenolic monomer pairs. A 46-fold purification of the peroxidase was achieved, and it was shown to be a 46 kDa haem peroxidase. Unlike other actinobacteria-derived peroxidases, it was only inhibited (27 % inhibition) by relatively high concentrations of sodium azide (5 mM) and was capable of oxidising eleven (2,4-dichlorophenol, 2,6-dimethoxyphenol, 4-tert-butylcatechol, ABTS, caffeic acid, catechol, guaiacol, l-DOPA, o-aminophenol, phenol, pyrogallol) of the seventeen substrates tested. The peroxidase remained stable at temperatures of up to 80 °C for 60 min and retained >50 % activity after 24 h between pH 5.0–9.0, but was most sensitive to incubation with hydrogen peroxide (H2O2; 0.01 mM), l-cysteine (0.02 mM) and ascorbate (0.05 mM) for one hour. It was significantly inhibited by all organic solvents tested (p ≤ 0.05). The Km and Vmax values of the partially purified peroxidase with the substrate 2,4-DCP were 0.95 mM and 0.12 mmol min−1, respectively. The dyes reactive blue 4, reactive black 5, and Azure B, were all decolourised to a certain extent: approximately 30 % decolourisation was observed after 24 h (1 μM dye). The peroxidase successfully catalysed coupling reactions between several phenolic monomer pairs including catechin-caffeic acid, catechin-catechol, catechin-guaiacol and guaiacol-syringaldazine under the non-optimised conditions used in this study. Genome sequencing confirmed the identity of strain BSII#1 as a S. albidoflavus strain. In addition, the genome sequence revealed the presence of one peroxidase gene that includes the twin arginine translocation signal sequence of extracellular proteins. Functional studies confirmed that the peroxidase produced by S. albidoflavus BSII#1 is part of the dye-decolourising peroxidase (DyP-type) family.The National Research Foundation (NRF) of South Africa and the Water Research Commission (WRC).http://www.elsevier.com/locate/enzmictec2021-09-03hj2021Biochemistr

Fruit waste streams in South Africa and their potential role in developing a bio-economy

Current and previous studies on bio-based (fruit) wastes and wastewaters, with a particular emphasis on research in South Africa, were reviewed. Previous studies have focused predominantly on the beneficiation and application of fruit waste as a feedstock for renewable energy. A definite gap in knowledge and application of fruit waste streams with regard to enzyme production as a value-added product is identified. The characteristics and composition of each type of fruit waste are highlighted and their potential as feedstocks in the production of value-added products is identified. The conversion of agri-industrial wastewaters to bioenergy and value-added products is discussed, with special mention of the newly published South African Bio-Economy Strategy, and the potential production of biofuels and enzymes from waste streams using recombinant Aspergillus strains. Finally, to maximise utilisation of waste streams in South Africa and abroad, a conceptual model for an integrated system using different technologies is proposed