Lab Results Fermenter

OBJECTIVES:

To determine the amount of anti-microbial peptide production by Staphylococcus warneri under various conditions when 2L and 10L Fermented. To Test the effects of one uncontrolled parameters sush as pH, Temperature or dissolved Oxygen and compare findings. To produce anti-microbial activity from Staphylococcus warneri.

INTRODUCTION:

Staphylococcus warneri is a member of bacterial genus Staphylococcus, consisting of Gram-positive bacteria with spherical cells appearing in clusters. Colonies of S. warneri are usually tan, yellow and about 2-4mm in diameter after 48 hours incubation at 35°C.

It is commonly found as part of the skin flora on humans and animals. S. warneri rarely causes disease, but may occasionally cause infection in patients whose immune system is compromised. S. warneri is known to produce antimicrobial peptide activity in the form of Nisin. The optimum conditions for this to occur are pH 7. Nisin is a polycylic antibacterial peptide with 34 amino acid residues used as a food preservative. It is produced by bacterium and which contains antimicrobial activity and which is known as a bacteriocin. Nisin has been found to have properties that can control spoilage caused by lactic acid bacteria.

It is used in processed cheese, meats, beverages, etc. during production to extend shelf life by suppresing Gram-positive spoilage and pathogenic bacteria. In food it is common to use Nisin at levels depending on the food type regulatory approval. Nisin cannot be produced chemically therefore it has to be synthesised using fermentation. During fermentation various stages of growth occur and as a result different conditions can occur during this fermentation process, eg pH, most organisms produce acid as they grow and therefore in the Lag phase ( a period of adptation for the cells to their new environment, new enzymes are ynthesized) and in the lag phase can produce alkaline substances and therefore pH plays an important role in efficient fermentation. As acid is produced alkaline substance needs to be added to the process to maintain the optimum pH of 7 and likewise in the lag phase when alkaline substances are produced, acidic substance needs to be added to maintain the pH, temperature, and oxygen. III. MATERIALS AND METHODS:“As per manual. ”

RESULTS:

All parameters are controlled using sensor probes in the vessels connected to a data logging software system. The vessels 4 and 5 are controls where the optimum environmental growth parameters for the strain are kept. To determine the results obtained in each vessels are as follows: Vessel 1: No antimicrobial peptide activity seen at any of the time intervals. This indicates that when temperature is not controlled the temperature can increase significantly. As shows in TABLE 1. 1 History Plot Vessel 1 – 2L NO Temperature control. Vessel 2: No antimicrobial activity seen at 13:00.

However antimicrobial activity seen in both neat and 1:2 sample at 14:00 and 15:00. Antimicrobial activity seen in neat sample at 16:00 and 09:00. When air flow is not controlled the reduced air content reduces the rate of fermentation, As Oxygen is required for cell growth and when air is in reduced quantity this slows down rate of cell reproduction as shows in TABLE 1. 2 History Plot Vessel 2 – 2L NO Air Flow. Vessel 3: Antimicrobial activity seen in neat sample at all time intervals. Antimicrobial activity seen in 1:2 sample at 14:00, 16:00 and 09:00.

Activity seen in 1:4 for the first time at 16:00 and 09:00. There is greater anti-microbial peptide activity with temperature and air controls which shows that the pH does not have significant effects as the other two parameters. The fermentation was not affected to the same extent by pH as shown in TABLE 1.

History Plot Vessel 3 – 2L NO pH control. Vessel 4: Antimicrobial activity seen in neat sample at all time intervals. Activity seen in 1:2 sample at 14:00, 15:00, 16:00 and 09:00. For the first time see antimicrobial activity in 1:8 sample at 09:00.

This shows the three uncontrolled vessels has greater anti-microbial peptide, where in fermentation took place on its fastest rate as all conditions are maintained at most favourable for the organism to grow and reproduced as shown in TABLE 1. 4 History Plot Vessel 4 – 2L Optimum conditions. Vessel 5: (In error no result recorded for 14:00 time interval) Antimicrobial activity seen in neat and 1:2 sample at all time intervals. Activity seen in 1:4 and 1:8 (for the first time) at 15:00, 16:00 and 09:00. The effects produce the highest level of anti-microbial peptide activity of all the system.

The organism has greater supply of oxygen and nutrients and temperature and pH has a lesser effect due to the larger volume as shown in TABLE 1.

History Plot Vessel 5 – 10L Optimum conditions.

CONCLUSIONS:

In this practical the results was successfully determined that Temperature is the most important parameter to control in relation to microbial growth. Therefore, if temperature was not controlled, NO amount of anti-microbial peptide activity produced by Staphylococcus warneri. While in Oxygen level and pH level if NOT controlled S. warneri will still grow and produced the anti-microbial peptide.