Assessment of cultivation parameters influencing pectinase production by Aspergillus niger LFP-1 in submerged fermentation.

BACKGROUND: Pectinase is helpful in food and beverage industries, particularly in the preparation of fruit juice, the extraction of vegetable oil, and the fermentation of coffee. The current work aimed to screen Aspergillus niger LFP-1, a recently identified fungal strain, for its ability to produce pectinase and to ascertain the contribution of various physicochemical factors to pectinase production. RESULTS: The primary and secondary pectinase activity screenings by Aspergillus niger LFP-1 were performed using pectin screening agar and shake flask system, respectively. The finding revealed that the locally isolated strain is able to secrete favourable pectinase production. Before improvement, the pectinase production was 0.88 ± 0.09 U/mL. However, the improved conditions such as 6 days of the cultivation period, agitation speed of 150 rpm, inoculum size of 1 × 106 spores/mL, 2.5% (w/v) citrus pectin, and 0.4% (w/v) ammonium nitrate could significantly increase pectinase production up to 7.41 ± 0.24 U/mL, representing an 88% increase. In this study, supplementing 2.5% (w/v) citrus pectin to the culture medium as a carbon source increased enzyme production by up to 3.07 ± 0.17 U/mL. Meanwhile, 0.4% (w/v) ammonium nitrate was used as a nitrogen source yielding the highest enzyme activity with a value of 6.86 ± 0.07 U/mL. CONCLUSION: Thus, the locally isolated fungal strain, A. niger LFP-1 has outstanding pectinase-producing capability and can be utilized for the commercial production of pectinase. The improved cultural conditions significantly increase pectinase production and shorten the incubation period from 8 days (before improvement) to 6 days (after improvement).

RhoG's Role in T Cell Activation and Function.

The role of RhoG in T cell development is redundant with other Racs subfamily members, and this redundancy may be attributed to redundant signal transduction pathways. However, the absence of RhoG increases TCR signalling and proliferation, implying that RhoG activity is critical during late T cell activation following antigen-receptor interaction. Moreover, RhoG is required to halt signal transduction and prevent hyper-activated T cells. Despite increase in TCR signalling, cell proliferation is inhibited, implying that RhoG induces T cell anergy by promoting the activities of transcription factors, including nuclear factor of activated T cell (NFAT)/AP-1. The role of NFAT plays in T cell anergy is inducing the transcription of anergy-associated genes, such as IL-2, IL-5, and IFN-γ. Although information about RhoG in T cell-related diseases is limited, mutant forms of RhoG, Ala151Ser and Glu171Lys have been observed in thymoma and hemophagocytic lymphohistiocytosis (HLH), respectively. Current information only focuses on these two diseases, and thus the role of RhoG in normal and pathological circumstances should be further investigated. This approach is necessary because RhoG and its associated proteins represent prospective targets for attack particularly in the therapy of cancer and immune-mediated illnesses.

Novel Nematode-Killing Protein-1 (Nkp-1) from a Marine Epiphytic Bacterium Pseudoalteromonas tunicata.

Drug resistance among parasitic nematodes has resulted in an urgent need for the development of new therapies. However, the high re-discovery rate of anti-nematode compounds from terrestrial environments necessitates a new repository for future drug research. Marine epiphytes are hypothesised to produce nematicidal compounds as a defence against bacterivorous predators, thus representing a promising yet underexplored source for anti-nematode drug discovery. The marine epiphytic bacterium Pseudoalteromonas tunicata is known to produce several bioactive compounds. Screening heterologously expressed genomic libraries of P. tunicata against the nematode Caenorhabditis elegans, identified as an E. coli clone (HG8), shows fast-killing activity. Here we show that clone HG8 produces a novel nematode-killing protein-1 (Nkp-1) harbouring a predicted carbohydrate-binding domain with weak homology to known bacterial pore-forming toxins. We found bacteria expressing Nkp-1 were able to colonise the C. elegans intestine, with exposure to both live bacteria and protein extracts resulting in physical damage and necrosis, leading to nematode death within 24 h of exposure. Furthermore, this study revealed C. elegans dar (deformed anal region) and internal hatching may act as a nematode defence strategy against Nkp-1 toxicity. The characterisation of this novel protein and putative mode of action not only contributes to the development of novel anti-nematode applications in the future but reaffirms the potential of marine epiphytic bacteria as a new source of novel biomolecules.

Carbapenem Resistance among Marine Bacteria-An Emerging Threat to the Global Health Sector.

The emergence of antibiotic resistance among pathogenic microorganisms is a major issue for global public health, as it results in acute or chronic infections, debilitating diseases, and mortality. Of particular concern is the rapid and common spread of carbapenem resistance in healthcare settings. Carbapenems are a class of critical antibiotics reserved for treatment against multidrug-resistant microorganisms, and resistance to this antibiotic may result in limited treatment against infections. In addition to in clinical facilities, carbapenem resistance has also been identified in aquatic niches, including marine environments. Various carbapenem-resistant genes (CRGs) have been detected in different marine settings, with the majority of the genes incorporated in mobile genetic elements, i.e., transposons or plasmids, which may contribute to efficient genetic transfer. This review highlights the potential of the marine environment as a reservoir for carbapenem resistance and provides a general overview of CRG transmission among marine microbes.

The Role of RhoH in TCR Signalling and Its Involvement in Diseases.

As an atypical member of the Rho family small GTPases, RhoH shares less than 50% sequence similarity with other members, and its expression is commonly observed in the haematopoietic lineage. To date, RhoH function was observed in regulating T cell receptor signalling, and less is known in other haematopoietic cells. Its activation may not rely on the standard GDP/GTP cycling of small G proteins and is thought to be constitutively active because critical amino acids involved in GTP hydrolysis are absent. Alternatively, its activation can be regulated by other types of regulation, including lysosomal degradation, somatic mutation and transcriptional repressor, which also results in an altered protein expression. Aberrant protein expression of RhoH has been implicated not only in B cell malignancies but also in immune-related diseases, such as primary immunodeficiencies, systemic lupus erythematosus and psoriasis, wherein its involvement may provide the link between immune-related diseases and cancer. RhoH association with these diseases involves several other players, including its interacting partner, ZAP-70; activation regulators, Vav1 and RhoGDI and other small GTPases, such as RhoA, Rac1 and Cdc42. As such, RhoH and its associated proteins are potential attack points, especially in the treatment of cancer and immune-related diseases.

Combating Parasitic Nematode Infections, Newly Discovered Antinematode Compounds from Marine Epiphytic Bacteria.

Parasitic nematode infections cause debilitating diseases and impede economic productivity. Antinematode chemotherapies are fundamental to modern medicine and are also important for industries including agriculture, aquaculture and animal health. However, the lack of suitable treatments for some diseases and the rise of nematode resistance to many available therapies necessitates the discovery and development of new drugs. Here, marine epiphytic bacteria represent a promising repository of newly discovered antinematode compounds. Epiphytic bacteria are ubiquitous on marine surfaces where they are under constant pressure of grazing by bacterivorous predators (e.g., protozoans and nematodes). Studies have shown that these bacteria have developed defense strategies to prevent grazers by producing toxic bioactive compounds. Although several active metabolites against nematodes have been identified from marine bacteria, drug discovery from marine microorganisms remains underexplored. In this review, we aim to provide further insight into the need and potential for marine epiphytic bacteria to become a new source of antinematode drugs. We discuss current and emerging strategies, including culture-independent high throughput screening and the utilization of Caenorhabditis elegans as a model target organism, which will be required to advance antinematode drug discovery and development from marine microbial sources.

Novel multifunctional iron chelators of the aroyl nicotinoyl hydrazone class that markedly enhance cellular NAD+ /NADH ratios.

BACKGROUND AND PURPOSE: Alzheimer's disease (AD) is a multifactorial condition leading to cognitive decline and represents a major global health challenge in ageing populations. The lack of effective AD therapeutics led us to develop multifunctional nicotinoyl hydrazones to target several pathological characteristics of AD. EXPERIMENTAL APPROACH: We synthesised 20 novel multifunctional agents based on the nicotinoyl hydrazone scaffold, which acts as a metal chelator and a lipophilic delivery vehicle, donating a NAD+ precursor to cells, to target metal dyshomeostasis, oxidative stress, ß-amyloid (Aß) aggregation, and a decrease in the NAD+ /NADH ratio. KEY RESULTS: The most promising compound, 6-methoxysalicylaldehyde nicotinoyl hydrazone (SNH6), demonstrated low cytotoxicity, potent iron (Fe)-chelation efficacy, significant inhibition of copper-mediated Aß aggregation, oxidative stress alleviation, effective donation of NAD+ to NAD-dependent metabolic processes (PARP and sirtuin activity) and enhanced cellular NAD+ /NADH ratios, as well as significantly increased median Caenorhabditis elegans lifespan (to 1.46-fold of the control); partly decreased BACE1 expression, resulting in significantly lower soluble amyloid precursor protein-ß (sAPPß) and Aß1-40 levels; and favourable blood-brain barrier-permeation properties. Structure-activity relationships demonstrated that the ability of these nicotinoyl hydrazones to increase NAD+ was dependent on the electron-withdrawing or electron-donating substituents on the aldehyde- or ketone-derived moiety. Aldehyde-derived hydrazones containing the ONO donor set and electron-donating groups were required for NAD+ donation and low cytotoxicity. CONCLUSIONS AND IMPLICATIONS: The nicotinoyl hydrazones, particularly SNH6, have the potential to act as multifunctional therapeutic agents and delivery vehicles for NAD+ precursors for AD treatment.