Screening, purification, and characterization of an extracellular lipase from Aureobasidium pullulans isolated from stuffed buns steamers

Role of AplaeA in the regulation of spore production and poly(malic acid) synthesis in Aureobasidium pullulans

Poly(malic acid) (PMLA) as one of the important metabolites in Aureobasidium pullulans has great application in a variety of fields. LaeA, a global regulator capable of controlling fungal secondary metabolites, has been identified in A. pullulans. The involvement of LaeA in the biosynthesis of PMLA through direct or indirect means and its role in A. pullulans is currently unknown. Here we extracted and characterized the AplaeA gene from A. pullulans HIT-LCY3T and resolved it by bioinformatics. The function of AplaeA was subsequently characterized by Rnai-LaeA and OEX-LaeA mutants. Based on phenotypic observations of the mutant strains, it was found that the gene had a large effect on the morphology and melanin production aspects of the strain, and that overexpression of the AplaeA gene resulted in a substantial increase in spore numbers. RT-qPCR combined with protein interactions results analyzed that ApLaeA positively regulates PMLA biosynthesis by controlling the expression of core genes of PMLA biosynthesis gene cluster and other related regulatory factors. Finally, OEX-LaeA was used as the starting strain to obtain the optimal fermentation conditions. These findings illustrate the regulatory mechanism of a hypothesized global regulator, LaeA, in A. pullulans HIT-LCY3T, suggesting its potential application in industrial-scale PMLA biosynthesis.

Phenotypic and genetic characterization of a lipolytic Ralstonia mannitolilytica isolate from petroleum-contaminated soil in Iraq

BACKGROUND

Lipases play a crucial role in various industrial applications, and microbial lipases, particularly those from bacteria, possess significant properties. With increasing concerns about the environmental and health impacts of hydrocarbons from pipelines and refineries, there is a growing need to mitigate the risks associated with these compounds.

METHODS

In this study, 40 bacterial isolates were recovered from contaminated soil samples collected from multiple refineries across Iraq. Using the Vitek system, bacterial isolates were identified up to the species level, revealing that only 12 isolates exhibited lipase-producing capabilities.

RESULTS

Among the lipase-producing isolates, Ralstonia mannitolilytica demonstrated the highest extracellular lipase activity, as determined by an olive oil plate assay supplemented with rhodamine B. Confirmation of the species identity was achieved through 16S rRNA gene sequencing, with the obtained sequence deposited under accession number LC772176.1. Further sequence analysis revealed single nucleotide polymorphisms (SNPs) in the genome of Ralstonia mannitolilytica strain H230303-10_N19_7x_R2 (CP011257.1, positions 1,311,102 and 1,311,457). Additionally, the presence of the lipase gene was confirmed through amplification and sequencing using a thermocycler PCR. Sequence analysis of the gene, aligned using Geneious Prime software, identified SNPs (CP010799, CP049132, AY364601, CP011257, and CP023537), and a phylogenetic tree was constructed based on genetic characterization.

CONCLUSION

Our findings highlight the potential of Ralstonia mannitolilytica as a promising candidate for lipase production and contribute to our understanding of its genetic diversity and biotechnological applications in hydrocarbon degradation and industrial processes.

Transcriptome Analysis Reveals the Regulation of Aureobasidium pullulans under Different pH Stress

Aureobasidium pullulans (A. pullulans), a commonly found yeast-like fungus, exhibits adaptability to a wide range of pH environments. However, the specific mechanisms and regulatory pathways through which A. pullulans respond to external pH remain to be fully understood. In this study, we first sequenced the whole genome of A. pullulans using Nanopore technology and generated a circle map. Subsequently, we explored the biomass, pullulan production, melanin production, and polymalic acid production of A. pullulans when cultivated at different pH levels. We selected pH 4.0, pH 7.0, and pH 10.0 to represent acidic, neutral, and alkaline environments, respectively, and examined the morphological characteristics of A. pullulans using SEM and TEM. Our observations revealed that A. pullulans predominantly exhibited hyphal growth with thicker cell walls under acidic conditions. In neutral environments, it primarily displayed thick-walled spores and yeast-like cells, while in alkaline conditions, it mainly assumed an elongated yeast-like cell morphology. Additionally, transcriptome analysis unveiled that A. pullulans orchestrates its response to shifts in environmental pH by modulating its cellular morphology and the expression of genes involved in pullulan, melanin, and polymalic acid synthesis. This research enhances the understanding of how A. pullulans regulates itself in diverse pH settings and offers valuable guidance for developing and applying engineered strains.

A critical review on exploitation of agro-industrial biomass as substrates for the therapeutic microbial enzymes production and implemented protein purification techniques

Annually, a huge amount of waste is generated by the industries that use agricultural biomass. Researchers have looked into employing this cheap and renewable agro-biomass as a substrate for enzyme production via fermentation processes to meet the ever-increasing worldwide need. Although there are a number of sources for enzyme extraction, microbial sources have dominated industrial sectors due to their easy availability and rapid growth. Microbial enzymes are currently used in a variety of industries, including pharmaceuticals, food, biofuels, textiles, paper, detergents, and so on, and using these nutritious feedstocks not only reduces production costs but also helps to reduce environmental concerns. The present review focuses on the therapeutic microbial enzymes produced using different agro-industrial biomass as raw materials, with down-streaming techniques for obtaining a final pure product. Additionally, the article also discussed biomass pretreatment processes, including physical, chemical and biological. The type of pretreatment method to be used is mostly governed by the intended use of the major molecular components of biomass (cellulose, hemicelluloses and lignin). Finally, purification challenges are included. All of this information will be useful in the industrial synthesis of high-purity targeted enzymes if the crucial aspects that have been discussed are taken into account.

Production, purification and biochemical characterisation of a novel lipase from a newly identified lipolytic bacterium Staphylococcus caprae NCU S6

A novel lipase, SCNL, was isolated from Staphylococcus caprae NCU S6 strain in the study. The lipase was purified to homogeneity with a yield of 6.13% and specific activity of 502.76 U/mg, and its molecular weight was determined to be approximately 87 kDa. SCNL maintained above 80% of its initial activity at a wide range of temperatures (20-50 °C) and pH values (6-11), with an optimal temperature at 40 °C and optimal pH at 9.0 with p-nitrophenyl palmitate as a substrate. SCNL exhibited a higher residual activity than the other staphylococcal lipases in the presence of common enzyme inhibitors and commercial detergents. The lipase activity was enhanced by organic solvents (isooctane, glycerol, DMSO and methanol) and metal ions (Na⁺, Ba²⁺, Ca²⁺, and Mn²⁺). The Km and Vmax values of SCNL were 0.695 mM and 262.66 s^-1mM^-1, respectively. The enzyme showed a preference for p-NP stearate, tributyrin and canola oil. These biochemical features of SCNL suggested that it may be an excellent novel lipase candidate for industrial and biotechnological applications.