Karl Rumbold

• PhD
• Professor at FH Campus Wien

The growing interest in using rhizobia as inoculants in sustainable agricultural systems has prompted the screening of rhizobia species for beneficial traits that enhance nodulation and nitrogen fixation under abiotic stressed conditions. This study reports phenotypic and phylogenetic characterization of rhizobia strains previously isolated from th...

Carboxylic acid reductases (CARs) are well-known for their eminent selective one-step synthesis of carboxylic acids to aldehydes. To date, however, few CARs have been identified and characterized, especially from fungal sources. In this study, the CAR from the white rot fungus Pycnoporus cinnabarinus (PcCAR2) was expressed in Escherichia coli. PcCA...

The corm of Hypoxis hemerocallidea, commonly known as the African potato, is used in traditional medicine to treat several medical conditions such as urinary infections, benign prostate hyperplasia, inflammatory conditions and testicular tumours. The metabolites contributing to the medicinal properties of H. hemerocallidea have been identified in s...

Bioethanol from abundant and inexpensive agricultural and industrial wastes possesses the potential to reduce greenhouse gas emissions. Bioethanol as renewable fuel addresses elevated production costs, as well as food security concerns. Although technical advancements in simultaneous saccharification and fermentation have reduced the cost of produc...

Recent studies on population genomics of Saccharomyces cerevisiae have substantially improved our understanding of the genetic diversity and domestication history of the yeast. However, the origin of the domesticated population of S. cerevisiae and the genomic changes responsible for ecological adaption of different populations and lineages remain...

Background: Acid mine drainage (AMD) leads to contamination of surface and ground water by high levels of toxic metals including chromium. In many cases, these waters are sources of drinking water for communities, and treatment is therefore required before consumption to prevent negative health effects. Methods: Cationised hemp cellulose was prepar...

Biological sulfate reduction offers prospects to co-treat a variety of organic and inorganic waste effluents because of the ability of sulfate reducing bacteria (SRB) to reduce sulfate to sulfide and generating alkalinity while using organic substrates for their metabolism. SRB are found in sulfate rich waters such as acid mine drainage (AMD). AMD...

Containment of the COVID-19 pandemic relies on accurate data regarding symptoms, transmission, prevention, nature of the virus, strains, immunological factors, relevant demographic and behavioural factors, and control strategies. In South Africa, epidemiological infection data revealed 622,551 cases and 231 deaths per million population as of 29 Au...

Dichapetalum cymosum produces the toxic fluorinated metabolite, fluoroacetate, presumably as a defence mechanism. Given the rarity of fluorinated metabolites in nature, the biosynthetic origin and function of fluoroacetate have been of particular interest. However, the mechanism for fluorination in D. cymosum was never elucidated. More importantly,...

Cationised hemp cellulose was prepared by etherification with two quaternary ammonium salts: 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) and glycidyltrimethylammonium chloride (GTMAC) and examined for (i) the efficiency of Cr(VI) removal under acid mine-drainage (AMD) conditions, and (ii) antibacterial activity. Adsorbents were ch...

The treatment of acid mine drainage (AMD) using dissimilatory sulfate reduction (DSR) utilises the ability of sulfate reducing bacteria (SRB) to reduce sulfate to sulfide using organic compounds as electron donors. Given that AMD contains relatively low levels of organic matter, the electron donors need to be supplied externally to facilitate the b...

Hydroxynitrile lyases (HNLs) are sought-after, stereo-selective biocatalysts used in the agrochemical, pharmaceutical and fine chemical industries to produce cyanohydrin enantiomers. There are several approaches for the discovery of HNLs, most of which are methodologically demanding and not suitable for high-throughput. Bioprospecting studies to da...

The incorporation of fluorine has been shown to improve the biophysical and bioactive properties of several organic compounds. However, sustainable strategies of fluorination are needed. Fluorinases have the unique ability to catalyse a C-F bond, hence, have vast potential to be applied as biocatalysts in the preparation of fine chemicals. But fluo...

Legumes are an important source of protein in human diet and are mostly grown by smallholder farmers in South Africa. However, their growth and yield are mainly affected by the availability of nitrogen in the soil. The economic and ecological importance of legumes is evident by the high number of species that are cultivated and commercialized, as w...

Actinomycetes are the most important microorganisms for the industrial production of secondary metabolites with antimicrobial and anticancer properties. However, they have not been implicated in biorefineries. Here, we study the ability of the ε-poly-l-lysine producing Streptomyces albulus BCRC 11814 to utilize biodiesel-derived crude glycerol. S....

Slides of the oral presentation of the development of, and sensitivity analyses performed on, the flow sheets for three different reactor configurations for a process to remediate acid mine drainage (AMD) utilising sulfate reducing bacteria (SRB), and indigenous South African grasses as a carbon source. Presented at the 2nd International Conference...

Presentation given on the 5th July 2017 at the 2nd International Conference on Energy, Environment and Climate Change. The presentation investigation the potential a two-phase digestion system, using sequentially fed leach bed reactors (SLBR) and an up-flow anaerobic sludge bed (UASB), for the bioremediation of acid mine drainage. Three sources of...

Ferulic acid is a natural antioxidant found in various plants and serves as a precursor for various fine chemicals, including the flavouring agent vanillin. However, expensive extraction methods have limited the commercial application of ferulic acid, in particular for the enrichment of food substrates. A recombinantAspergillus tubingensisferulic a...

Introduction and background to the Industrial and Mining Water Research Unit (IMWaRU) at the University of the Witwatersrand, Johannesburg

This study assessed the capabilities of the dung beetle, Euoniticellus intermedius (Coleoptera: Scarabaeida), larva gut consortia in degrading cellulose that can serve as glucose source for biofuels production. A total of 144 live dung beetles were randomly collected from a dairy farm and bred in a temperature controlled insect rearing room. On rea...

Cashew apple juice (CAJ) is one of the feedstocks used for biofuel production and ethanol yield depends on the physical and chemical properties of the extracted juice. As far as can be ascertained, information on physical and chemical properties of South African cashew apple juice is limited in open literature. Therefore, this study provides inform...

The drainage from closed and abandoned mines is often acidic with elevated heavy metal concentrations. The interaction between acid mine drainage (AMD) and the environment has a significant impact. Whilst temporary remediation can lessen this impact, complete amelioration is only possible using active and/or passive treatment. Active technologies a...

Acid mine drainage (AMD) poses a serious threat to water quality in the Witwatersrand region (South Africa), owing to extensive mine voids that have been abandoned, and subsequently flooded. In response to the severity of the situation, the South African government has undertaken construction of facilities to lower the water level to a safe depth (...

Acid mine drainage (AMD) has long been considered to be an environmental hazard worldwide. South Africa faces a significant threat due from AMD, owing to its mining industry. Conventional methods of treating AMD are not always applicable. Constructed wetlands minimize some of these problems. These CWs rely mainly on microbial dissimilatory sulfate...

The drainage from closed and abandoned mines is often acidic with elevated heavy metal concentrations. The interaction between acid mine drainage (AMD) and the environment has a significant impact. Whilst temporary remediation can lessen this impact, complete amelioration is only possible using active and/or passive treatment. Active technologies a...

Nanoparticles (NPs) especially those of carbon nanotubes (CNTs) have remarkable properties that are very desirable in various biological and biomedical applications. This has necessitated the rapid study of CNT toxicities, to augment their safe use, particularly, in yeast cells. The yeast cell; Saccharomyces cerevisiae is a widely used industrial a...

Drought is one of the major production-limiting factors to agriculture and it has been predicted to increase in frequency, duration and intensity due to global climate change. The lack of water induces stomatal closure in plants, therefore decreasing levels of photosynthesis and the plant's ability to acquire nutrients1. Further decreases in plant...

Acid mine drainage (AMD) poses a serious threat to water quality in the Witwatersrand region, owing to extensive, abandoned mine voids that have subsequently flooded. The formation of AMD requires a sulphide mineral (primarily pyrite), water and oxygen to regenerate ferric iron in order to produce net acidity. In response to the severity of the cur...

During the last few decades, Streptomycetes have shown to be a very important and adaptable group of bacteria for the production of various beneficial secondary metabolites. These secondary metabolites have been of great interest in academia and the pharmaceutical industries. To date, a vast variety of techniques and tools for metabolic engineering...

Hydroxynitrile lyases are used for the synthesis of enantiomerically pure cyanohydrins which are of great importance in the pharmaceutical and fine chemical industries. In this study, the hydroxynitrile lyase activity of 100 plants from 40 families was investigated, first by screening for cyanogenic activity, followed by a hydroxynitrile lyase acti...

Species of actinobacteria previously isolated from Tyume River in the Eastern Cape Province of South Africa and identified by 16S rDNA sequence as Cellulomonas and Streptomyces species were evaluated as a consortium for the production of bioflocculant. Sucrose, peptone and magnesium chloride were the nutritional sources which supported optimal prod...

The production of ferulic acid esterase involved in the release of ferulic acid side groups from xylan was investigated in strains of Aspergillus tubingensis, Aspergillus carneus, Aspergillus niger and Rhizopus oryzae. The highest activity on triticale bran as sole carbon source was observed with the A. tubingensis T8.4 strain, which produced a typ...

Background: The applications of oxidized carbon nanotubes (o-CNTs) have shown potentials in novel drug delivery including the brain which is usually a challenge. This underscores the importance to study its potential toxic effect in animals. Despite being a promising tool for biomedical applications little is known about the safety of drugs in tre...

Over 3,000 plant species are cyanogenic. Cyanogenesis is defined as the hydroxynitrile lyase catalysed release of a cyanide group in the form of HCN and the corresponding aldehyde or ketone. When a plant is attacked, HCN released is a self defence mechanism. A special characteristic of enzymatic reactions is that all enzymatic reactions are reversi...

Here, we report the draft genome sequence of Streptomyces albulus strain CCRC 11814, a soil-dwelling, Gram-positive bacterium. S. albulus produces ε-poly-l-lysine, which has diverse antimicrobial activity. The genome is 9.43 Mb in size, with a G+C content of 72.2%, and contains 9,177 protein-coding sequences.

We reported earlier on the bioflocculant production potential of Halobacillus sp. Mvuyo, a marine bacteria isolated from Algoa Bay sediment samples. In this paper we report on the detailed characterization of the purified bioflocculant composed of polysaccharide and protein. The optimum dose of the purified bioflocculant for the clarification of 4...

We evaluated the bioflocculant production potential of an Actinobacteria, which was isolated from a freshwater environment in the Eastern Cape province of South Africa. 16S rDNA nucleotide sequencing analyses revealed that the actinobacteria belongs to the Brachybacterium genus, and the sequences were deposited in the GenBank as Brachybacterium sp....

In this study, we report on the bioflocculant production potential of an Oceanobacillus sp. isolated from the marine sediments of Algoa Bay. The bacteria produced an extracellular bioflocculant optimally in the presence of sodium carbonate as source of carbon with flocculating activity of about 95.5%. Other optimal culture conditions included: tryp...

Bioethanol as a fossil fuel additive to decrease environmental pollution and reduce the stress of the decline in crude oil availability is becoming increasingly popular. This study aimed to evaluate the concentration of bioethanol obtainable from fermenting cashew apple juice by the microorganism Saccharomyces cerevisiae Y2084 and Vin13. The fermen...

Here, we report the draft genome sequence of Streptomyces albulus strain CCRC 11814, a soil-dwelling, Gram-positive bacterium. S. albulus produces ε-poly-L-lysine, which has diverse antimicrobial activity. The genome is 9.43 Mb in size, with a G+C content of 72.2%, and contains 9,177 protein-coding sequences.

Recently, interest in using bioethanol as an alternative to petroleum fuel has been escalating due to decrease in the availability of crude oil. The application of bioethanol in the motor-fuel industry can contribute to reduction in the use of fossil fuels and in turn to decreased carbon emissions and stress of the rapid decline in crude oil availa...

Energy fuels for transportation and electricity generation are mainly derived from finite and declining reserves of fossil hydrocarbons. Fossil hydrocarbons are also used to produce a wide range of organic carbon-based chemical products. The current global dependency on fossil hydrocarbons will not be environmentally or economically sustainable in...

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Increasingly lignocellulosic biomass hydrolysates are used as the feedstock for industrial fermentations. These biomass hydrolysates consist of complex mixtures of different fermentable sugars, but also contain inhibitors and salts that affect the performance of the product-generating microbes. The performance of six industrially relevant microorga...

South Africa and the world at large are in a dire need to abate unprecedented CO2 levels that are believed to be causing unstable environment, phenomena generally called climate change. Microalgae are photosynthetic aquatic microorganism. They are promising to be a sustainable means of mitigating green house gas emissions and their biomass has valu...

Increasingly lignocellulosic biomass hydrolysates are used as the feedstock for industrial fermentations. These biomass hydrolysates are complex mixtures of different fermentable sugars, but also inhibitors and salts that affect the performance of the microbial production host. The performance of six industrially relevant microorganisms, i.e. two b...

Hydroxynitrile lyases (Hnls) are important biocatalysts for the synthesis of optically pure cyanohydrins, which are used as precursors and building blocks for a wide range of high price fine chemicals. Although two Hnl enzymes, from the tropical rubber tree Hevea brasiliensis and from the almond tree Prunus amygdalus, are already used for large sca...

Microbial metabolomics has received much attention in recent years mainly because it supports and complements a wide range of microbial research areas from new drug discovery efforts to metabolic engineering. Broadly, the term metabolomics refers to the comprehensive (qualitative and quantitative) analysis of the complete set of all low molecular w...

The thermostability of the endo-beta-1,4-xylanase from Thermomyces lanuginosus (xynA) was improved by directed evolution using error-prone PCR. Transformants expressing the variant xylanases were first selected on 0.4% Remazol Brilliant Blue-xylan and then exposed to 80 degrees C. Whereas the wild type XynA lost 90% activity after 10 min at 80 degr...

Feruloyl esterases (EC 3.1.1.73) are referred to as carbohydrate esterases with high specific activity for hydroxycinnamates. Generally these enzymes are found in supernatants of fungal and bacterial cultures grown on plant material or plant cell wall extracts. For the identification and characterization of feruloyl esterase activity a range of dif...

THERE HAVE BEEN TWO DISTINCT CHAPTERS in the history of converting cellulosic biomass to fuels and commodity chemicals in South Africa. The first chapter, from the late 1970s to the early 1990s, involved some of the most active research and development efforts of their kind anywhere in the world. Thereafter, during the second chapter, there has bee...

The lignocellulolytic fungus Aureobasidium pullulans NRRL Y 2311-1 produces feruloyl esterase activity when grown on birchwood xylan. Feruloyl esterase was purified from culture supernatant by ultrafiltration and anion-exchange, hydrophobic interaction, and gel filtration chromatography. The pure enzyme is a monomer with an estimated molecular mass...

The effect of the carbon source and supplemented free ferulic acid on the production of extracellular feruloyl esterase, beta-xylanase and alpha-arabinofuranosidase by Aureobasidium pullulans was examined. Aureobasidium pullulans was cultivated on birchwood xylan, oat spelt xylan glucose, xylose, sugarcane bagasse and dissolving pulp as carbon sour...

An on-line system based on microdialysis sampling (MD), micro-high performance anion exchange chromatography (micro-HPAEC), integrated pulsed electrochemical detection (IPED), and electrospray ionization mass spectrometry (MS) for the monitoring of on-line desalted enzymatic hydrolysates is presented. Continuous monitoring of the enzymatic degradat...

(S)-Hydroxynitrile lyase (Hnl) from the tropical rubber tree Hevea brasiliensis catalyzes the formation of (S)-cyanohydrins from hydrocyanic acid and aldehydes or ketones. This enzyme accepts aliphatic, aromatic, and heterocyclic carbonyl compounds as substrates and is therefore considered a potent biocatalyst for the industrial production of optic...