Metagenome-assembled genomes provide insight into the microbial taxonomy and ecology of the Buhera soda pans, Zimbabwe.

The use of metagenomics has substantially improved our understanding of the taxonomy, phylogeny and ecology of extreme environment microbiomes. Advances in bioinformatics now permit the reconstruction of almost intact microbial genomes, called metagenome-assembled genomes (MAGs), from metagenomic sequence data, allowing for more precise cell-level taxonomic, phylogenetic and functional profiling of uncultured extremophiles. Here, we report on the recovery and characterisation of metagenome-assembled genomes from the Buhera soda pans located in eastern Zimbabwe.

Metagenomic insights into the microbial community of the Buhera soda pans, Zimbabwe.

Background: Soda pans are unique, natural aquatic environments characterised by elevated salinity and alkalinity, creating a distinctive and often extreme geochemistry. The microbiomes of soda pans are unique, with extremophiles such as halophiles, alkaliphiles and haloalkaliphiles being important. Despite being dominated by mostly unculturable inhabitants, soda pans hold immense biotechnological potential.

Enterobacter spp. isolates from an underground coal mine reveal ligninolytic activity.

Lignin, the second most abundant renewable carbon source on earth, holds significant potential for producing biobased specialty chemicals. However, its complex, highly branched structure, consisting of phenylpropanoic units and strong carbon-carbon and ether bonds, makes it highly resistant to depolymerisation. This recalcitrancy highlights the need to search for robust lignin-degrading microorganisms with potential for use as industrial strains.

Yeast-insect interactions in southern Africa: Tapping the diversity of yeasts for modern bioprocessing.

Yeast-insect interactions are one of the most interesting long-standing relationships whose research has contributed to our understanding of yeast biodiversity and their industrial applications. Although insect-derived yeast strains are exploited for industrial fermentations, only a limited number of such applications has been documented. The search for novel yeasts from insects is attractive to augment the currently domesticated and commercialized production strains.

Phytostabilization of fly ash from a coalmine in Botswana and biovalorisation of the recovered Napier grass ( Schumach.).

The disposal of fly ash (FA) from coal power plants polluting the air, soil, and groundwater is a major environmental concern. Phytoremediation to rehabilitate fly ash dumpsites is a promising alternative but has practical concerns about the disposal of harvested biomass. This study investigated the effect of supplementing fly ash with fresh sewage sludge (FSS), aged sewage sludge, food waste, and compost (COM) to enhance the phytoremediation potential of Napier grass and its subsequent utilization for ethanol production.

Dung beetle-associated yeasts display multiple stress tolerance: a desirable trait of potential industrial strains.

Background: Stress-tolerant yeasts are highly desirable for cost-effective bioprocessing. Several strategies have been documented to develop robust yeasts, such as genetic and metabolic engineering, artificial selection, and natural selection strategies, among others. However, the significant drawbacks of such techniques have motivated the exploration of naturally occurring stress-tolerant yeasts.

The and elephant intoxication myth: assessing the biodiversity of fermenting yeasts associated with marula fruits ().

The inebriation of wild African elephants from eating the ripened and rotting fruit of the marula tree is a persistent myth in Southern Africa. However, the yeasts responsible for alcoholic fermentation to intoxicate the elephants remain poorly documented. In this study, we considered Botswana, a country with the world's largest population of wild elephants, and where the marula tree is indigenous, abundant and protected, to assess the occurrence and biodiversity of yeasts with a potential to ferment and subsequently inebriate the wild elephants.

Do microbes evade domestication? - Evaluating potential ferality among diastatic Saccharomyces cerevisiae.

Certain lineages of the wine, beer and bread yeast Saccharomyces cerevisiae have diastatic activity. They contain the chimeric gene STA1 that codes for an extracellular glucoamylase which enables the strains to degrade starch and dextrins. Beer contaminations by diastatic yeasts can be dangerous because they can cause super-attenuation due to the consumption of otherwise non-fermentable oligosaccharides, gushing and off-flavours.

Diversity of dung beetle-associated yeasts from pristine environments of Botswana.

Yeast-insect interactions are increasingly becoming an attractive source of discovery for previously unknown, unique, diverse, and industrially relevant yeast species. Despite a wealth of studies that have recently focused on yeasts in symbiotic association with Hymenopteran insects, yeasts associated with Coleopteran insects, such as lignocellulosic-rich dung-dependent beetles, remain poorly studied. Trends in yeast discovery suggest that species richness and diversity can be attributed to the ecological niche of the insect.

Mycotoxins in , A Traditional Non-Cereal Based Alcoholic Beverage of Botswana.

Mycotoxin contamination is a major food safety drawback towards the commercialization of food products. The commercialization of , a popular fermented alcoholic beverage of Botswana necessitates the investigation of the presence of mycotoxins. brewing involves the uncontrolled and unstandardized spontaneous fermentation of sun-dried fruits, which could be a source of mycotoxin-producing filamentous fungi (molds).

Looking into the world's largest elephant population in search of ligninolytic microorganisms for biorefineries: a mini-review.

Gastrointestinal tracts (GIT) of herbivores are lignin-rich environments with the potential to find ligninolytic microorganisms. The occurrence of the microorganisms in herbivore GIT is a well-documented mutualistic relationship where the former benefits from the provision of nutrients and the latter benefits from the microorganism-assisted digestion of their recalcitrant lignin diets. Elephants are one of the largest herbivores that rely on the microbial anaerobic fermentation of their bulky recalcitrant low-quality forage lignocellulosic diet given their inability to break down major components of plant cells.

Evolutionary engineering to improve Wickerhamomyces subpelliculosus and Kazachstania gamospora for baking.

The conventional baker's yeast, Saccharomyces cerevisiae, is the indispensable baking yeast of all times. Its monopoly coupled to its major drawbacks, such as streamlined carbon substrate utilisation base and a poor ability to withstand a number of baking associated stresses, prompt the need to search for alternative yeasts to leaven bread in the era of increasingly complex consumer lifestyles. Our previous work identified the inefficient baking attributes of Wickerhamomyces subpelliculosus and Kazachstania gamospora as well as preliminarily observations of improving the fermentative capacity of these potential alternative baker's yeasts using evolutionary engineering.

Functional Characterization of Yeasts Isolates for Selection of Starter Cultures.

Yeasts play an important role in spontaneous fermentation of traditional alcoholic beverages. Our previous study revealed that a mixed-consortia of both and non- yeasts were responsible for fermentation of , a popular, non-standardized traditional beverage with an immense potential for commercialization in Botswana. Functional characterization of isolated fermenting yeasts from mixed consortia is an indispensable step towards the selection of potential starter cultures for commercialization of .

Biosurfactant production by halophilic yeasts isolated from extreme environments in Botswana.

Nine morphologically distinct halophilic yeasts were isolated from Makgadikgadi and Sua pans, as pristine and extreme environments in Botswana. Screening for biosurfactant production showed that Rhodotorula mucilaginosa SP6 and Debaryomyces hansenii MK9 exhibited the highest biosurfactant activity using Xanthocercis zambesiaca seed powder as a novel and alternative inexpensive carbon substrate. Chemical characterization of the purified biosurfactants by Fourier Transform Infra-Red spectroscopy suggested that the biosurfactant from R.

Complete Genome Sequence of an Antimicrobial-Producing Bacillus velezensis Sam8H1 Isolate from the Makgadikgadi Saltpans of Botswana.

The global antimicrobial drug resistance crisis requires urgency in searching for more effective broad-spectrum antimicrobial drugs. Here, we present a complete circular genome sequence and a plasmid of an antimicrobial-producing isolate, strain Sam8H1, from the Makgadikgadi saltpans in Botswana. Bioinformatic analyses revealed 12 putative secondary metabolite biosynthetic gene clusters important for genome-guided drug discovery studies.

Bioethanolic yeasts from dung beetles: tapping the potential of extremophilic yeasts for improvement of lignocellulolytic feedstock fermentation.

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 production, one major drawback of this technology is that the pre-treatment process creates environmental stressors inhibitory to fermentative yeasts subsequently reducing bioethanol productivity.

Biodiesel's trash is a biorefineries' treasure: the use of "dirty" glycerol as an industrial fermentation substrate.

"Dirty" glycerol from biodiesel production is having a considerable environmental impact since its disposal is expensive and difficult. The increased biodiesel production in the last two decades has forced glycerol prices down, thereby making it now unprofitable for chemical companies to produce. The problem lies with the impurities of the biodiesel conversion process usually ending up within the crude glycerol fraction.

Experimental evolution: its principles and applications in developing stress-tolerant yeasts.

Stress tolerance and resistance in industrial yeast strains are important attributes for cost-effective bioprocessing. The source of stress-tolerant yeasts ranges from extremophilic environments to laboratory engineered strains. However, industrial stress-tolerant yeasts are very rare in nature as the natural environment forces them to evolve traits that optimize survival and reproduction and not the ability to withstand harsh habitat-irrelevant industrial conditions.

Improvement of thermotolerance in Lachancea thermotolerans using a bacterial selection pressure.

The use of thermotolerant yeast strains is an important attribute for a cost-effective high temperature biofermentation processes. However, the availability of thermotolerant yeast strains remains a major challenge. Isolation of temperature resistant strains from extreme environments or the improvements of current strains are two major strategies known to date.

Streptomyces albulus yields ε-poly-L-lysine and other products from salt-contaminated glycerol waste.

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.

Genome dynamics and evolution in yeasts: A long-term yeast-bacteria competition experiment.

There is an enormous genetic diversity evident in modern yeasts, but our understanding of the ecological basis of such diversifications in nature remains at best fragmented so far. Here we report a long-term experiment mimicking a primordial competitive environment, in which yeast and bacteria co-exist and compete against each other. Eighteen yeasts covering a wide phylogenetic background spanning approximately 250 million years of evolutionary history were used to establish independent evolution lines for at most 130 passages.

Yeast-bacteria competition induced new metabolic traits through large-scale genomic rearrangements in Lachancea kluyveri.

Large-scale chromosomal rearrangements are an important source of evolutionary novelty that may have reshaped the genomes of existing yeast species. They dramatically alter genome organization and gene expression fueling a phenotypic leap in response to environmental constraints. Although the emergence of such signatures of genetic diversity is thought to be associated with human exploitation of yeasts, less is known about the driving forces operating in natural habitats.

Kazachstania gamospora and Wickerhamomyces subpelliculosus: Two alternative baker's yeasts in the modern bakery.

Saccharomyces cerevisiae, the conventional baker's yeast, remains the most domesticated yeast monopolizing the baking industry. Its rapid consumption of sugars and production of CO are the most important attributes required to leaven the dough. New research attempts highlight that these attributes are not unique to S.

Coevolution with bacteria drives the evolution of aerobic fermentation in Lachancea kluyveri.

The Crabtree positive yeasts, such as Saccharomyces cerevisiae, prefer fermentation to respiration, even under fully aerobic conditions. The selective pressures that drove the evolution of this trait remain controversial because of the low ATP yield of fermentation compared to respiration. Here we propagate experimental populations of the weak-Crabtree yeast Lachancea kluyveri, in competitive co-culture with bacteria.