Microplastic pollution is globally recognised as a serious environmental threat due to its ubiquitous presence related primarily to improper dumping of plastic wastes. While most studies have focused on microplastic contamination in the marine ecosystem, microplastic pollution in the soil environment is generally little understood and often overlooked. The presence of microplastics affects the soil ecosystem by disrupting the soil fertility and quality, degrading the food web, and subsequently influencing both food security and human health. This study evaluates the growth and biodegradation potential of the Antarctic soil bacteria Pseudomonas sp. ADL15 and Rhodococcus sp. ADL36 on the polypropylene (PP) microplastics in Bushnell Haas (BH) medium for 40 days. The degradation was monitored based on the weight loss of PP microplastics, removal rate constant per day (K), and their half-life. The validity of the PP microplastics’ biodegradation was assessed through structural changes via Fourier transform infrared spectroscopy analyses. The weight loss percentage of the PP microplastics by ADL15 and ADL36 after 40 days was 17.3% and 7.3%, respectively. The optimal growth in the BH media infused with PP microplastics was on the 40th and 30th day for ADL15 and ADL36, respectively. The infrared spectroscopic analysis revealed significant changes in the PP microplastics’ functional groups following the incubation with Antarctic strains.

Rhodococci are renowned for their great metabolic repertoire partly because of their numerous putative pathways for large number of specialized metabolites such as biosurfactant. Screening and genome-based assessment for the capacity to produce surface-active molecules was conducted on Rhodococcus sp. ADL36, a diesel-degrading Antarctic bacterium. The strain showed a positive bacterial adhesion to hydrocarbon (BATH) assay, drop collapse test, oil displacement activity, microplate assay, maximal emulsification index at 45% and ability to reduce water surface tension to < 30 mN/m. The evaluation of the cell-free supernatant demonstrated its high stability across the temperature, pH and salinity gradient although no correlation was found between the surface and emulsification activity. Based on the positive relationship between the assessment of macromolecules content and infrared analysis, the extracted biosurfactant synthesized was classified as a lipopeptide. Prediction of the secondary metabolites in the non-ribosomal peptide synthetase (NRPS) clusters suggested the likelihood of the surface-active lipopeptide production in the strain’s genomic data. This is the third report of surface-active lipopeptide producers from this phylotype and the first from the polar region. The lipopeptide synthesized by ADL36 has the prospect to be an Antarctic remediation tool while furnishing a distinctive natural product for biotechnological application and research.

Aptamers are a group of synthetic single-stranded nucleic acids. They are generated from a random library of single-stranded DNA or RNA by a technology named systematic evolution of ligands by exponential enrichment (SELEX). SELEX is a repetitive process to select and identify suitable aptamers that show high affinity and specificity towards target cells. Great strides have been achieved in the design, construction, and use of aptamers up to this point. However, only a small number of aptamer-based applications have achieved widespread commercial and clinical acceptance. Additionally, finding more effective ways to acquire aptamers with high affinity remains a challenge. Therefore, it is crucial to thoroughly examine the existing dearth and advancement in aptamer-related technologies. This review focuses on aptamers that are generated by SELEX to detect pathogenic microorganisms and mammalian cells, as well as in cell-internalizing SELEX for diagnostic and therapeutic purposes. The development of novel aptamer-based biosensors using optical and electrical methods for microbial detection is reported. The applications and limitations of aptamers are also discussed.

We have developed a method for rapid quenching of samples taken from chemostat cultures of Escherichia coli that gives reproducible and reliable measurements of extracellular and intracellular metabolites by ¹ H NMR and have applied it to study the major central metabolites during the transition from anaerobic to aerobic growth. Almost all metabolites showed a gradual change after perturbation with air, consistent with immediate inhibition of pyruvate formate-lyase, dilution of overflow metabolites and induction of aerobic enzymes. Surprisingly, although pyruvate showed almost no change in intracellular concentration, the extracellular concentration transiently increased. The absence of intracellular accumulation of pyruvate suggested that one or more glycolytic enzymes might relocate to the cell membrane. To test this hypothesis, chromosomal pyruvate kinase ( pykF ) was modified to express either PykF-green fluorescent protein or PykF-FLAG fusion proteins. Measurements showed that PykF-FLAG relocates to the cell membrane within 5 min of aeration and then slowly returns to the cytoplasm, suggesting that on aeration, PykF associates with the membrane to facilitate secretion of pyruvate to maintain constant intracellular levels.

The application of microorganisms in azo dye remediation has gained significant attention, leading to various published studies reporting different methods for obtaining the best dye decolouriser. This paper investigates and compares the role of methods and media used in obtaining a bacterial consortium capable of decolourising azo dye as the sole carbon source, which is extremely rare to find. It was demonstrated that a prolonged acclimation under low substrate availability successfully isolated a novel consortium capable of utilising Reactive Red 120 dye as a sole carbon source in aerobic conditions. This consortium, known as JR3, consists of Pseudomonas aeruginosa strain MM01, Enterobacter sp. strain MM05 and Serratia marcescens strain MM06. Decolourised metabolites of consortium JR3 showed an improvement in mung bean’s seed germination and shoot and root length. One-factor-at-time optimisation characterisation showed maximal of 82.9% decolourisation at 0.7 g/L ammonium sulphate, pH 8, 35 °C, and RR120 concentrations of 200 ppm. Decolourisation modelling utilising response surface methodology (RSM) successfully improved decolourisation even more. RSM resulted in maximal decolourisation of 92.79% using 0.645 g/L ammonium sulphate, pH 8.29, 34.5 °C and 200 ppm RR120.

Major progress in the fields of agriculture, industry, and biotechnology over the years has influenced the quest for a potent microorganism with favorable properties to be used in scientific research and industry. This study intended to isolate a new thermophilic-protease-producing bacterium and evaluate its growth and protease production under cultural conditions. Protease producing bacteria were successfully isolated from Sungai Klah Hot Spring Park in Perak, Malaysia, and coded as SKF4; they were promising protease producers. Based on microscopic, morphological, and 16S rRNA gene analysis, isolate SKF4 was identified as Geobacillus thermoglucosidasius SKF4. The process of isolating SKF4 to grow and produce proteases under different cultural conditions, including temperature, pH, NaCl concentration, carbon and nitrogen sources, and incubation time, was explored. The optimum cultural conditions observed for growth and protease production were at 60 to 65 °C of temperature, pH 7 to 8, and under 1% NaCl concentration. Further, the use of casein and yeast extract as the nitrogen sources, and sucrose and fructose as the carbon sources enhanced the growth and protease production of isolate SKF4. Meanwhile, isolate SKF4 reached maximum growth and protease production at 24 h of incubation time. The results of this study revealed a new potent strain of thermophilic bacterium isolated from Sungai Klah Hot Spring Park in Perak, Malaysia for the first time. The high production of thermostable protease enzyme by G. thermoglucosidasius SKF4 highlighted the promising properties of this bacterium for industrial and biotechnological applications.