Bacterial Secondary Metabolism

Vocabulary flashcards on bacterial secondary metabolism, covering primary and secondary metabolites, regulation, and specific examples like g-butyrolactones, bacteriocins, and nisin.

Primary Metabolites

Metabolites that form during the exponential growth phase of a microorganism and are essential for growth; an example is ethanol production during fermentative energy metabolism.

Secondary Metabolites

Metabolites that usually form at the end of exponential growth or during the stationary phase and are not essential for growth/reproduction.

g-Butyrolactones (Butanolides)

Regulatory molecules found in actinomycetes (Gram-positive bacteria) that induce their own production and affect development, sporulation, and antibiotic production.

N-acylhomoserine lactones (AHL)

Regulatory molecules found in Gram-negative bacteria (e.g., Lux system of Vibrio fischeri) that induce their own production and are involved in various processes like light emission and virulence.

Oligopeptides

Regulatory molecules found in Gram-positive bacteria (e.g., Bacteriocins) that function in development, sporulation, and production of antibiotics.

A-factor

A g-butyrolactone produced by Streptomyces that induces morphological and chemical differentiation and is involved in streptomycin production.

ArpA

A-factor receptor protein in S. griseus that acts as a transcriptional repressor; when A-factor binds to it, the repressor is removed, allowing gene expression.

AdpA

A master regulator that up-regulates StrR and is involved in the regulation of streptomycin biosynthesis downstream of A-factor.

StrR

An activator of Streptomycin biosynthesis.

Bacteriocins

Bacterially produced, small, heat-stable peptides that are active against other bacteria, with the producer having a specific immunity mechanism.

Lantibiotics

Modified peptides (bacteriocins) containing lanthionine and are produced by Gram-positive bacteria.

Nisin

A lantibiotic produced by lactic acid bacteria (LAB) and used commercially as a food additive to prevent bacteria-mediated food spoilage.

Lanthionine

A modified amino acid found in lantibiotics, formed when dehydrated serine or threonine condenses with cysteine.

Quorum Sensing

A regulatory mechanism where bacteria sense their cell density and regulate gene expression, often influencing bacteriocin production.

ABC Transporter

An ATP-binding cassette transporter involved in the secretion of bacteriocins, which cleaves off a leader peptide during translocation across the membrane.