Lukhanyo Mekuto

Biodegradation of Free Cyanide Using Bacillus Sp. Consortium Dominated by Bacillus Safensis, Lichenformis and Tequilensis Strains: A Bioprocess Supported Solely with Whey

Several bacterial species (n=13) were isolated from electroplating wastewater to assess their ability to biodegrade free cyanide (F-CN). A mixed culture mainly dominated by Bacillus sp (Bacillus safensis, Bacillus lichenformis and Bacillus tequilensis) was cultured in nutrient broth for 48 hours at 37°C, to which F-CN as KCN (200 to 400 mg CN-/L) was added in order to evaluate the species ability to tolerate and biodegrade the cyanide. In nutrient broth, the microorganisms were able to degrade 131(65.5%) and 177 (44.3%) mg CN-/L in cultures containing 200 and 400 mg CN-/L over a period of 8 days, respectively. Subsequently, cultures were supplemented solely with agrowaste extracts, i.e. Ananas comosus extract (1% v/v), Beta vulgaris extract (1% v/v), Ipomea batatas extract (1% v/v), spent brewer’s yeast (1% v/v) and whey (0.5% w/v), as the primary carbon sources in 200 and 400 mg CN-/L cultures. The bacterial species were able to degrade F-CN in cultures that were supplemented with whey, whereby 179 (89.5%) and 239 (59.75%) mg CN-/L was biodegraded from 200 and 400 mg CN-/L cultures, respectively.

An integrated biological approach for treatment of cyanidation wastewater

The cyanidation process has been, and still remains, a profitable and highly efficient process for the recovery of precious metals from ores. However, this process has contributed to environmental deterioration and potable water reserve contamination due to the discharge of poorly treated, or untreated, cyanide containing wastewater. The process produces numerous cyanide complexes in addition to the gold cyanocomplex. Additionally, the discharge constituents also include hydrogen cyanide (HCN) - metallic complexes with iron, nickel, copper, zinc, cobalt and other metals; thiocyanate (SCN); and cyanate (CNO). The fate of these complexes in the environment dictates the degree to which these species pose a threat to living organisms. This paper reviews the impact that the cyanidation process has on the environment, the ecotoxicology of the cyanidation wastewater and the treatment methods that are currently utilised to treat cyanidation wastewater. Furthermore, this review proposes an integrated biological approach for the treatment of the cyanidation process wastewater using microbial consortia that is insensitive and able to degrade cyanide species, in all stages of the proposed process.

Isolation of high-salinity-tolerant bacterial strains, Enterobacter sp., Serratia sp., Yersinia sp., for nitrification and aerobic denitrification under cyanogenic conditions.

Cyanides (CN(-)) and soluble salts could potentially inhibit biological processes in wastewater treatment plants (WWTPs), such as nitrification and denitrification. Cyanide in wastewater can alter metabolic functions of microbial populations in WWTPs, thus significantly inhibiting nitrifier and denitrifier metabolic processes, rendering the water treatment processes ineffective. In this study, bacterial isolates that are tolerant to high salinity conditions, which are capable of nitrification and aerobic denitrification under cyanogenic conditions, were isolated from a poultry slaughterhouse effluent. Three of the bacterial isolates were found to be able to oxidise NH(4)-N in the presence of 65.91 mg/L of free cyanide (CN(-)) under saline conditions, i.e. 4.5% (w/v) NaCl. The isolates I, H and G, were identified as Enterobacter sp., Yersinia sp. and Serratia sp., respectively. Results showed that 81% (I), 71% (G) and 75% (H) of 400 mg/L NH(4)-N was biodegraded (nitrification) within 72 h, with the rates of biodegradation being suitably described by first order reactions, with rate constants being: 4.19 h(-1) (I), 4.21 h(-1) (H) and 3.79 h(-1) (G), respectively, with correlation coefficients ranging between 0.82 and 0.89. Chemical oxygen demand (COD) removal rates were 38% (I), 42% (H) and 48% (G), over a period of 168 h with COD reduction being highest at near neutral pH.

Metagenomic data of free cyanide and thiocyanate degrading bacterial communities

The data presented in this article contains the bacterial community structure of the free cyanide (CN-) and thiocyanate (SCN-) degrading organisms that were isolated from electroplating wastewater and synthetic SCN- containing wastewater. PCR amplification of the 16S rRNA V1-V3 regions was undertaken using the 27F and 518R oligonucleotide primers following the metacommunity DNA extraction procedure. The PCR amplicons were processed using the illumina® reaction kits as per manufacturer׳s instruction and sequenced using the illumina® MiSeq-2000, using the MiSeq V3 kit. The data was processed using bioinformatics tools such as QIIME and the raw sequence files are available via NCBI׳s Sequence Read Archive (SRA) database.

Biochemical characteristics of a free cyanide and total nitrogen assimilating Fusarium oxysporum EKT01/02 isolate from cyanide contaminated soil

Sustainability of nutrient requirements for microbial proliferation on a large scale is a challenge in bioremediation processes. This article presents data on biochemical properties of a free cyanide resistant and total nitrogen assimilating fungal isolate from the rhizosphere of Zeamays (maize) growing in soil contaminated with a cyanide-based pesticide. DNA extracted from this isolate were PCR amplified using universal primers; TEF1-α and ITS. The raw sequence files are available on the NCBI database. Characterisation using biochemical data was obtained using colorimetric reagents analysed with VITEK® 2 software version 7.01. The data will be informative in selection of biocatalyst for environmental engineering application.

The role of pollutants in type 2 diabetes mellitus (T2DM) and their prospective impact on phytomedicinal treatment strategies

Type 2 diabetes mellitus (T2DM) is the most common form of diabetes and it is characterized by high blood sugar and abnormal sera lipid levels. Although the specific reasons for the development of these abnormalities are still not well understood, traditionally, genetic and lifestyle behavior have been reported as the leading causes of this disease. In the last three decades, the number of diabetic patients has drastically increased worldwide, with current statistics suggesting the number is to double in the next two decades. To combat this incurable ailment, orthodox medicines, to which economically disadvantaged patients have minimal access to, have been used. Thus, a considerable amalgamation of medicinal plants has recently been proven to possess therapeutic capabilities to manage T2DM, and this has prompted studies primarily focusing on the healing aspect of these plants, and ultimately, their commercialization. Hence, this review aims to highlight the potential threat of pollutants, i.e., polyfluoroalkyl compounds (PFCs), endocrine disrupting chemicals (EDCs) and heavy metals, to medicinal plants, and their prospective impact on the phytomedicinal therapy strategies for T2DM. It is further suggested that auxiliary research be undertaken to better comprehend the factors that influence the uptake of these compounds by these plants. This should include a comprehensive risk assessment of phytomedicinal products destined for the treatment of T2DM. Regulations that control the use of PFC-precursors in certain developing countries are also long overdue.

Recent developments in polyfluoroalkyl compounds research: a focus on human/environmental health impact, suggested substitutes and removal strategies

Between the late 1940s and early 1950s, humans manufactured polyfluoroalkyl compounds (PFCs) using electrochemical fluorination and telomerisation technologies, whereby hydrogen atoms are substituted by fluorine atoms, thus conferring unnatural and unique physicochemical properties to these compounds. Presently, there are wide ranges of PFCs, and owing to their bioaccumulative properties, they have been detected in various environmental matrices and in human sera. It has thus been suggested that they are hazardous. Hence, this review aims at highlighting the recent development in PFC research, with a particular focus on perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), the most studied and predominantly found PFCs in various environmental matrices, although recent reports have included perfluorobutane sulfonate (PFBS), which was previously regarded as innocuously harmless, when compared to its counterparts, PFOA and PFOS. As such, proper investigations are thus required for a better understanding of short-chain PFC substitutes, which have been suggested as suitable replacements to long-chained PFCs, although these substitutes have also been suggested to pose various health risks comparable to those associated with long-chain PFCs. Similarly, several novel technologies, such as PFC reduction using zero-valent iron, including removal at point of use, adsorption and coagulation, have been proposed. However, regardless of how efficient removers some of these techniques have proven to be, short-chain PFCs remain a challenge to overcome for scientists, in this regard.

Process performance determination data in thiocyanate biodegradation systems: Use of sulphate production

This data article presents the utilization of sulphates as an indirect technique for the assessment of microbial growth, activity and SCN- biodegradation efficiency since the TDO were observed to be unable to utilise the produced sulphates as a source of sulphur (Mekuto e al., 2017) [1] The TDO demonstrated complete SCN- biodegradation while also utilizing the produced ammonium. The production of SO42- from SCN- biodegradation had a good correlation in comparison to the traditional methods of assessing microbial growth and activity i.e. direct cell counts (DCC), heterotrophic counts (CFU) and fluorescein production from fluorescein diacetate (FDA). The concentration of the produced SO42- demonstrated a similar logarithmic trend with the FDA, DCC and CFU techniques, thus confirming that the production of SO42- from SCN- biodegradation systems can be utilised as an indirect technique for the assessment of microbial growth, activity and SCN- biodegradation performance.

Are Aquaporins (AQPs) the Gateway that Conduits Nutrients, Persistent Organic Pollutants and Perfluoroalkyl Substances (PFASs) into Plants?

Besides water and sunlight, plants and/or crops also require an assortment of dissimilar nutrients/elements to grow. Thus, some of these nutrients have been classified as essential or macronutrients, [e.g. calcium (Ca), magnesium (Mg) and sulphur (S)], for they facilitate plant growth; while others, such as copper (Cu), iron (Fe), zinc (Zn), etc., are considered as micronutrients. However, it is apparent now that plants are exposed to a variety of other chemical compounds, including a range of persistent organic pollutants (POPs) and perfluoroalkyl substances (PFASs), which have been found in several plants. Hence, it has been common knowledge that mechanisms, such as mass flow, diffusion, etc., facilitated by plant root systems, have allowed the translocation of these nutrients and pollutants into plants, although other researchers have argued that roots on their own cannot elucidate the dissemination of these chemical constituents into plants. This dissension remained until the discovery of aquaporins (AQPs), which ultimately led to numerous AQPs being identified in plants. Thus, the aim of this review is to present an overview on the progress made thus far in attempting to understand the possibility of these proteins (i.e. AQPs) being the gateway that conduits nutrients, POPs and PFASs into plants; however, the gathered evidence currently remains rudimentary and limited, suggesting that further research is required to elucidate plant AQPs involvement at this stage in POP transportation and storage in plants.

Kinetic modelling and optimisation of antimicrobial compound production by Candida pyralidae KU736785 for control of Candida guilliermondii

Biological antimicrobial compounds from yeast can be used to address the critical need for safer preservatives in food, fruit and beverages. The inhibition of Candida guilliermondii, a common fermented beverage spoilage organism, was achieved using antimicrobial compounds produced by Candida pyralidae KU736785. The antimicrobial production system was modelled and optimised using response surface methodology, with 22.5 ℃ and pH of 5.0 being the optimum conditions. A new concept for quantifying spoilage organism inhibition was developed. The inhibition activity of the antimicrobial compounds was observed to be at a maximum after 17–23 h of fermentation, with C. pyralidae concentration being between 0.40 and 1.25 × 109 CFU ml−1, while its maximum specific growth rate was 0.31–0.54 h−1. The maximum inhibitory activity was between 0.19 and 1.08 l contaminated solidified media per millilitre of antimicrobial compound used. Furthermore, the antimicrobial compound formation rate was 0.037–0.086 l VZI ml−1 ACU h−1, respectively. The response surface methodology analysis showed that the model developed sufficiently described the antimicrobial compound formation rate 1.08 l VZI ml−1 ACU, as 1.17 l VZI ml−1 ACU, predicted under the optimum production conditions.