Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/179291

Supplement comprising of laccase and citric acid as an alternative for antibiotics - in vitro triggers of melanin production

Chaali, M.·Lecka, J.·Suresh, G.·Salem, M.·Brar, S. K.·Hernandez-Galan, L.·Sevigny, J.·Avalos-Ramirez, A.
View original source ↗Export metadata ↓

Abstract

An indiscriminate use of antibiotics in humans and animals has led to a widespread selection of antibiotic-resistant bacterial strains. A possible solution to counter this problem could be to develop alternatives that may boost the host immunity, thus reducing in the quantity and frequency of antibiotic use. In this work, for the first time, citric acid and laccase were used as extracellular inducers of melanin production in yeast cells and human cell lines. It is proposed that the formulation of laccase and citric acid together could further promote melatonin stimulated melanocyte derived melanin production. Melanization test as a probe of immunity, described in this study, is an easy and a quicker test than the other immunity tests and is statistically significant. The results showed the synergistic effect of citric acid and laccase on melanin production by the yeast cells, with significant statistical differences compared to all other tested conditions (P: 0.0005- 0.005). Laccase and citric acid together boosted melanin production after 8 days of incubation. An increase in melanin production by two colon human cells lines (Cacao-2/15 and HT-29) was observed when both laccase and citric acid were present in cell growth medium. A formulation with citric acid and laccase may prove to be an excellent alternative to reduce the antibiotic load in human and animal subjects.\n\nSummary statementThis study shows, for the first time, that production of melanin in yeast and human intestinal cells is induced by extracellular addition of laccase and citric acid.

Source connections

Explore related subjects

immunologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Chaali, M., Lecka, J., Suresh, G., Salem, M., Brar, S. K., Hernandez-Galan, L., Sevigny, J., Avalos-Ramirez, A.. 2017-08-21. Supplement comprising of laccase and citric acid as an alternative for antibiotics - in vitro triggers of melanin production. https://doi.org/10.1101/179291

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

CD19-CAR T-cell therapy resets the EBV+ autoreactive B cell repertoire in autoimmune disease

Epstein-Barr virus (EBV) reprograms autoreactive B cells into activated antigen-presenting cells that drive pathogenic T- and B-cell responses in autoimmune disease. Using EBV B-cell sequencing (EBV-seq), we profiled EBV+ B cells in patients treated with CD19 chimeric antigen receptor (CAR) T cells (systemic lupus, n=6; idiopathic inflammatory myopathies, n=3; systemic sclerosis, n=3) or rituximab (n=15). CAR T cells, but not rituximab, depleted EBV+ B cells, resetting the repertoire toward a naive state: predominantly IgM+ with minimal somatic hypermutation. Post-rituximab B-cells remained class-switched, hypermutated, and activated. Monoclonal antibodies cloned from EBV+ B cells lost autoreactivity after CAR T cells but not rituximab. Sustained drug-free remission occurred in 8/12 CAR-treated but 0/15 rituximab-treated patients. EBV+ B cells were predominantly Latency III and resisted anti-CD20 and anti-CD19 antibodies, yet were killed by CAR T cells and T-cell engagers. CD19-CAR T-cell therapy resets the autoreactive EBV+ B-cell repertoire, which may underlie sustained drug-free remission.

immunology↗
bioRxiv2026

A minimal two-residue C-terminal truncation of AID in adult-onset hyper-IgM syndrome type 2 (HIGM2)

Activation-induced cytidine deaminase (AID), encoded by AICDA, facilitates class-switch recombination (CSR) and somatic hypermutation (SHM) in activated B cells. Loss of AID function causes hyper-IgM syndrome type 2 (HIGM2). While typically autosomal recessive, three C-terminal truncation variants have been reported to act in autosomal dominant manner. We describe a novel heterozygous AICDA nonsense variant, c.589G>T (p.G197*), that truncates the final two C-terminal residues of AID and results in adult-onset HIGM2. Single-cell sequencing of primary patient B cells revealed a complete block in CSR and a [~]10-fold reduction in SHM. AICDA mRNA expression was balanced between wild-type and variant alleles, yet AID protein abundance was reduced to [~]56% with normal subcellular localization. Remarkably, inducible germinal center (iGB) cultures restored CSR in purified naive patient B cells. CRISPR-Cas9 editing of healthy donor B cells confirmed that the iGB platform can rescue B cells harboring heterozygous, but not homozygous, AICDA variants. These results demonstrate that even a two-amino-acid truncation at the AID C-terminus is sufficient to disrupt its function and cause HIGM2.

immunology↗
bioRxiv2026

Defining the Functional Consequence of the Human Ocular Microbiome

The ocular surface is one of the body's most environmentally exposed mucosal barriers, yet it is considered low biomass and harbors orders of magnitude fewer bacteria than microbe-rich sites like the gut. This has cast doubt on whether a functional core ocular microbiome exists at all. Having previously defined a protective gd T cell and IL-17 axis engaged by the murine commensal Corynebacterium mastitidis, we asked whether human-derived bacteria could do the same. Pairing sequencing and culturomics of healthy human conjunctiva from two geographically distinct cohorts, we define a stable core microbiome and identify Corynebacterium bovis as a consistent eye-resident commensal rather than a transient contaminant. In humans, C. bovis elicits a non-pathogenic response marked by IL-17 secretion by {gamma}{delta} T cells and circulating C. bovis-specific IgG, which suggests commensalism rather than pathology. Colonizing mice with human C. bovis strains from Pittsburgh or Miami reproduced this program and conferred protection against ocular infection with Staphylococcus aureus. Together, these findings identify C. bovis as a human-derived ocular commensal that can drive protective {gamma}{delta} T cell immunity, translating a mechanism previously defined only in mice into human relevance and a rational target against sight-threatening infection.

immunology↗