Production of Antimicrobial Peptides

To appreciate the value of asceptic techniques in regards to to bacterial cell cultivation, progress, purity and last harvesting by bench centrifugation to be able to secure a supernatant with extracellular bacterial by-products. The production of bacteriocins by S. warneri was measured on a150mm agar plate inoculated with Kocuria rhizophila (A Gram-positive bacteria) to ascertain antimicrobial activity using serial dilutions of a S. warneri sample and positive and negative adjustments. The anti-microbial activity was likened up against the plotted data from the fermentation run to be able to study any results process variables such as pH, heat biomass and dissolved oxygen may have. Information from the fermentation run were also studied to determine cell progress conditions and exactly how local environmental changes affect the bacterial culture.


Fermentation is an energy-yielding anaerobic fat burning capacity where microrganisms convert nutrients (glucose) to alcohols and acids (lactic acid and acetic acid). The most commonly known fermentation process is the transformation of sweets to liquor, using fungus under anaerobic conditions. In biotech business, fermentation identifies the expansion of microorganisms on food, under either aerobic or anaerobic conditions. Bioreactors are used for industrial fermentation techniques and are made of glass, material or plastic with automated and/or manually controlled and settings to regulate aeration, stirring, temps, pressure and pH and can be small enough for bench-top applications (5-10 L) or up to 10, 000 L in convenience of large-scale industrial functions. Large bioreactors are being used in the pharmaceutical industry for the expansion of specialised clean cultures of bacteria, fungi and candida, and the development of enzymes and medication sunder strictly controlled conditions. The study and practice of fermentation is called zymology or zymurgy. Louis Pasteur was one of the first zymologists and he described fermentation as "the consequence of life without air".

Lactic Acid Fermentation

The pyruvate sugar molecules from glucose metabolism known as glycolysis, may be fermented into lactic acid. Industrial bioreactors are used to convert lactose into lactic acid in the creation of yogurt. Lactic acid is also produced muscletissue when the cells is under stress and requires energy quicker than oxygen can be offered. The equation for lactic acid development from sugar is:

C6H12O6 (blood sugar)  ' 2 CH3CHOHCOOH

(lactic acid)

The development of lactic acid from lactose and water may be summarized as:


Bacterial cultures are being used for several professional and research purposes like the development of microbial supplementary metabolites such as enzymes, anti biotics and bacteriocins which are very like antibiotic and were formerly classed consequently. So monitoring bacterial expansion in bioreactors is important to exploit this secondary metabolism.

Bacterial growth in batch culture can be modelled in four different phases: a lag period, an exponential or log period accompanied by a stationary period with your final death period. The stationary stage is the growth-limiting phase because there is a depletion of nutrients with a related climb of inhibitory products such as bacteriocins. In this period of bacterial progress, the cell development rate and death count have the same worth. At the loss of life phase, the bacteria go out of nutrition and expire. Batch culture is the most common laboratory growth method as it is ultimately spatially unstructured and temporally organised. Batch culture kinetics indicates that the exponential progress phase decreases to give a deceleration stage because of the depletion of essential nutrition and accumulation of poisonous by-products. As there is no net growth, bacteria will point their metabolism to create extra metabolites. The bacteria produce several secondary metabolites including antibacterial toxins such as bacteriocins to help stave off any microbial competition for these scarce extra nutrient sources. These bacteriocins can be cultured industrially and accumulated (1).

Bacteriocins are bacterial peptides that work as toxins produced by bacterias to inhibit the progress of carefully related bacterial strains. They are really secondary metabolites produced through the first forty eight hours of the early stationary phase and are synthesised from precursor peptides that range in their amino acid sequences (2). Most share common features such as low molecular weight, cathionic and hydrophobic, high temperature stablility and all are coded by structural genes that are translated into working peptides by microbial ribosomes. (2). They are also highly protected to intestinal enzymes and can inhibit the progress of parasites and Candida species. Bacteriocins are cationic membrane lively compounds that destroy microorganisms by permeating the microbial membrane and impairing the cells ability to carry out anaerobic respiration. That is an important characteristic as bacteriocins are unlikely to handle the same antimicrobial resistance mechanisms that limit current antibiotic pathways. Bacteriocins and antibiotics change is that bacteriocins restrict their activity to strains of types related to the producing kinds and specifically to strains of the same types. Antibiotics display a lot better activity spectrum range and even though their activity is restricted, no preferential effect on meticulously related strains is witnessed (2).

They have been recognized in abundance during the creation of probiotics or natural antibiotics. Probiotics, such as improved yogurt are advantageous microorganisms that are presented into food so that they can re-colonise the G I tract. These bacteria generally are a group known as lactic acid bacterias, especially species of Lactobaccillus. Lactic acid bacteria convert sugars to lactic acid in the lack of oxygen (1). They were first found out in 1925 by Gratin who also went on to develop a range of antibiotics and found out the bacteriophage. The first bacteriocin was called colicine, since it wiped out Escherichia coli (1). Colicins (From Gram-negative bacteria) were used as prototype bacteriocins that all other bacteriocin analysis was compared to and will be the most examined. Four classes of bacteriocins are described as follows:

Class 1 Bacteriocins: These are small peptide inhibitors such as nisin, produced by Lactococcus lactis, and subtilin, a nisin analogue and Streptococcus types which produce lantbiotics including the widely researched, lactic acid bacteria (LAB).

ClassII Bacteriocins: These are the small temperature stable peptides, usually <10kDa. There are five sub-classes. The class IIa bacteriocins are the most significant subclass and are pediocin like bacteriocins, each filled with a seven amino acid concensus series at the N-terminal while the C-terminal is accountable for species specific cell death, usually by permeating the cell wall structure and necrotic cell leakage.

Class IIb are so called two-peptide bacteriocins as two different peptides are necessary for activity. They includes the alpha enterocins and lactococcin G peptides which act as pore-forming toxins that permeates the cell membrane to provide channels with a barrel-stave mechanism. This helps create an ion imbalance and leakage in the cell, leading to cell fatality.

ClassIIc include the cyclic peptides. Here the N- and C-terminals are covalently bonded to provide circular bacteriocins. They result membrane permeability and cell wall membrane formation on goal skin cells. Bacteriocin AS-48 which is made by Enterococcus faecalis (a streptococcus bacterium) shows a variety of antimicrobial mechanisms against both Gram-Negative and Gram-Positive bacteria. Bacteriocin AS-48 is encoded by a pheromone responsive plasmid, pMB2 and episodes the plasma membrane where it punches pores leading to an ion imbalance, resulting in leakage and cell loss of life. The globular structure of bacteriocin AS-48 contains five alpha helices enclosing a hydrophobic primary.

Class IId: These are the one peptide bacteriocins and display no post translational alterations or any pediocin like characteristics. One example is aureocin A53, which is stable under acidic pH conditions which is resistant to several proteases.

Class IIe: Aureocin A70 is encoded in a 8 kb plasmid, pRJ6, and comprises four peptides with 30 or 31 amino acid residues lacking any N-terminal leader collection. It is toxic against Listeria monocytogenes, a facultative anaerobic bacterium and dangerous virulent food-borne pathogen, with 20-30 % of specialized medical infections resulting in death.

Class III Bacteriocins: They are large high temperature labile bacteriocins of >10kDa. You can find two subclasses.

Class IIIa: These bacteriocins kill other bacterial skin cells by cell wall structure degdaration resulting in cell lysis. The best known is lysostaphin, a27kDa necessary protein that lysises many of the staphylococcus types, especially S. aureus.

ClassIIIb: This subclass consists of those bacteriocins that not cause cell lysis. They destroy other bacterial skin cells by disrupting the cells membrane potential enabling a net APT efflux.

Class IV Bacteriocins: They are really large, warmth labile complex bacteriocins with different lipid and carbohydrate useful groups.

Staphylococcus warneri Bacteriocin

Nukacin ISK-I is a linear, type A(II) lantibiotic produced by S. Warneri of molecular weight 2. 96kDa and is also encoded on plasmid pPI-1 on six distinct genes. Nukacin ISK-1 is made up of three lanthioine molecules and/or three 3-methyllanthionine molecules, thus rendering it a lantibiotic. Type A lantibiotic protein punch pores into the cytoplasmic membranes of sensitive cells leading to cell loss of life as well as providing immunity protein against self types produced lantibiotics by covalently binding free lantibiotic across the cell membrane (7).

Material and Methods

All work was done according to the manual.


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