Browsing by Author "Den Haan, Riaan"

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    The detection of meningococcal disease through identification of antimicrobial peptides using an in silico model creation
    (University of the Western Cape, 2019) Abdullah, Gadija; Pretorius, Ashley; Den Haan, Riaan
    Neisseria meningitidis (the meningococcus), the causative agent of meningococcal disease (MD) was identified in 1887 and despite effective antibiotics and partially effective vaccines, Neisseria meningitidis (N. meningitidis) is the leading cause worldwide of meningitis and rapidly fatal sepsis usually in otherwise healthy individuals. Over 500 000 meningococcal cases occur every year. These numbers have made bacterial meningitis a top ten infectious cause of death worldwide. MD primarily affects children under 5 years of age, although in epidemic outbreaks there is a shift in disease to older children, adolescents and adults. MD is also associated with marked morbidity including limb loss, hearing loss, cognitive dysfunction, visual impairment, educational difficulties, developmental delays, motor nerve deficits, seizure disorders and behavioural problems. Antimicrobial peptides (AMPs) are molecules that provide protection against environmental pathogens, acting against a large number of microorganisms, including bacteria, fungi, yeast and virus. AMPs production is a major component of innate immunity against infection. The chemical properties of AMPs allow them to insert into the anionic cell wall and phospholipid membranes of microorganisms or bind to the bacteria making it easily detectable for diagnostic purposes. AMPs can be exploited for the generation of novel antibiotics, as biomarkers in the diagnosis of inflammatory conditions, for the manipulation of the inflammatory process, wound healing, autoimmunity and in the combat of tumour cells. Due to the severity of meningitis, early detection and identification of the strain of N. meningitidis is vital. Rapid and accurate diagnosis is essential for optimal management of patients and a major problem for MD is its diagnostic difficulties and experts conclude that with an early intervention the patient’ prognosis will be much improved. It is becoming increasingly difficult to confirm the diagnosis of meningococcal infection by conventional methods. Although polymerase chain reaction (PCR) has the potential advantage of providing more rapid confirmation of the presence of the bacterium than culturing, it is still time consuming as well as costly. Introduction of AMPs to bind to N. meningitidis receptors could provide a less costly and time consuming solution to the current diagnostic problems. World Health Organization (WHO) meningococcal meningitis program activities encourage laboratory strengthening to ensure prompt and accurate diagnosis to rapidly confirm the presence of MD. This study aimed to identify a list of putative AMPs showing antibacterial activity to N. meningitidis to be used as ligands against receptors uniquely expressed by the bacterium and for the identified AMPs to be used in a Lateral Flow Device (LFD) for the rapid and accurate diagnosis of MD.
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    Enabling the production of black soldier fly larval protein from lignocellulosic biomass through pre-treatment and enzymatic hydrolyse
    (University of the Western Cape, 2023) Bothma, Michaela; Den Haan, Riaan
    Due to the rapid increase in the world’s population, alternative food resources are crucial to sustain the human diet. Insects can produce valuable proteins and nutrients that can be used as high-quality animal feedstuff and help to reduce organic waste. Hermetia illucens, also known as the Black soldier fly, has attracted the attention of researchers due to the veracious nature of the fly larvae (BSFL). These insects can be reared on any organic waste, consuming large quantities of raw organic material more efficiently and faster compared to other known fly species. While consuming organic waste, BSFL build up their body composition to approximately 30% fat and 40% protein, which can be a substitute for nutritionally comparable fishmeal in pet foods and animal feed. Although BSFL are mainly used for animal feed, they represent a promising source of nutrients for human consumption, although limited knowledge regarding the use of BSFL for human consumption is available. Lignocellulose could serve as an alternative, “clean” feedstock consisting of carbohydrates, that can be fed to Black soldier fly larvae.
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    Stress modulation as a means to improve yeasts for lignocellulose bioconversion
    (Springer, 2021) Brandt, Bianca; Jansen, Trudy; Den Haan, Riaan
    The second-generation (2G) fermentation environment for lignocellulose conversion presents unique challenges to the fermentative organism that do not necessarily exist in other industrial fermentations. While extreme osmotic, heat, and nutrient starvation stresses are observed in sugar- and starch-based fermentation environments, additional pre-treatment-derived inhibitor stress, potentially exacerbated by stresses such as pH and product tolerance, exist in the 2G environment. Furthermore, in a consolidated bioprocessing (CBP) context, the organism is also challenged to secrete enzymes that may themselves lead to unfolded protein response and other stresses. This review will discuss responses of the yeast Saccharomyces cerevisiae to 2G-specific stresses and stress modulation strategies that can be followed to improve yeasts for this application. We also explore published –omics data and discuss relevant rational engineering, reverse engineering, and adaptation strategies, with the view of identifying genes or alleles that will make positive contributions to the overall robustness of 2G industrial strains.