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Production of Antimicrobial Peptides

Production of Antimicrobial Peptides. To appreciate the importance of asceptic techniques with regard to bacterial cell cultivation, growth, purity and final harvesting by bench centrifugation in order to obtain 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 determine antimicrobial activity using serial dilutions of a S. warneri sample and positive and negative controls. The anti-microbial activity was compared against the plotted data from the fermentation run in order to study any effects process variables such as pH, temperature biomass and dissolved oxygen may have. Profiles from the fermentation run were also studied to determine cell growth conditions and how local environmental changes affect the bacterial culture. Introduction Fermentation is an energy-yielding anaerobic metabolic process in which microrganisms convert nutrients (carbohydrates) to alcohols and acids (lactic acid and acetic acid). The most commonly known fermentation process is the conversion of sugar to alcohol, using yeast under anaerobic conditions. In biotech industries, fermentation refers to the growth of microorganisms on food, under either aerobic or anaerobic conditions. Bioreactors are used for industrial fermentation processes and are made of glass, metal or plastic with automatic and/or manually controlled and settings to control aeration, stirring, temperature, pressure and pH and can be small enough for bench-top applications (5-10 L) or up to 10,000 L in capacity for large-scale industrial processes. Large bioreactors are used in the pharmaceutical industry for the growth of specialised pure cultures of bacteria, fungi and yeast, and the production of enzymes and drug 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 referred to fermentation as “the result 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 production of yogurt. Lactic acid is also produced muscletissue when the tissue is under stress and requires energy at a faster rate than oxygen can be supplied. The equation for lactic acid production from glucose is: C6H12O6 (glucose) †’ 2 CH3CHOHCOOH (lactic acid) The production of lactic acid from lactose and water may be summarized as: CH3CHOHCOOH H2O †’ 4 CH3CHOHCOOH Bacterial cultures are used for several industrial and research purposes including the production of microbial secondary metabolites such as enzymes, anti biotics and bacteriocins which are very like antibiotic and were originally classed as such. As such monitoring bacterial growth in bioreactors is important to exploit this secondary metabolism. Bacterial growth in batch culture can be modelled in four different phases: a lag phase, an exponential or log phase followed by a stationary phase with a final death phase. The stationary phase is the growth-limiting phase because there is a depletion of nutrients with a corresponding rise of inhibitory products such as bacteriocins. In this phase of bacterial growth, the cell growth rate and death rate have the same values. At the death phase, the bacteria run out of nutrients and die. Batch culture is the most common laboratory growth method as it is ideally spatially unstructured and temporally structured. Batch culture kinetics indicates that the exponential growth phase slows down to give a deceleration phase due to the depletion of essential nutrients and accumulation of toxic by-products. As there is no net growth, bacteria will direct their metabolism to produce secondary metabolites. The bacteria produce several secondary metabolites including antibacterial toxins such as bacteriocins to help stave off any microbial competition for these scarce secondary nutrient sources. These bacteriocins can be cultured industrially and collected (1). Bacteriocins are bacterial peptides that behave as toxins produced by bacteria to inhibit the growth of closely related bacterial strains. They are secondary metabolites produced during the first forty eight hours of the early stationary phase and are synthesised from precursor peptides that vary in their amino acid sequences (2). Most share common features such as low molecular weight, cathionic and hydrophobic, heat stablility and all are coded by structural genes that are translated into working peptides by microbial ribosomes. (2).They are also highly resistant to intestinal enzymes and can inhibit the growth of harmful bacteria and Candida species. Bacteriocins are cationic membrane active compounds that kill microorganisms by permeating the microbial membrane and impairing the cells ability to carry out anaerobic respiration. This is an important trait as bacteriocins are unlikely to face the same antimicrobial resistance mechanisms that limit current antibiotic pathways. Bacteriocins and antibiotics differ is that bacteriocins restrict their activity to strains of species related to the producing species and in particular to strains of the same species. Antibiotics display a far greater activity spectrum range and even when their activity is restricted, no preferential effect on closely related strains is observed (2). They have been detected in abundance during the production of probiotics or natural antibiotics. Probiotics, such as enhanced yogurt are beneficial microorganisms that are introduced into food so that they can re-colonise the G I tract. These bacteria are usually a group known as lactic acid bacteria, especially species of Lactobaccillus. Lactic acid bacteria convert sugars to lactic acid in the absence of oxygen (1). They were first discovered in 1925 by Gratin who also went on to develop a range of antibiotics and discovered the bacteriophage. The first bacteriocin was called colicine, because it killed Escherichia coli (1). Colicins (From Gram-negative bacteria) were used as prototype bacteriocins from which all other bacteriocin analysis was compared to and are the most studied. 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 species which produce lantbiotics such as the widely studied, lactic acid bacteria (LAB). ClassII Bacteriocins: These are the small heat stable peptides, usually <10kDa. There are five sub-classes. The class IIa bacteriocins are the largest subclass and are pediocin like bacteriocins, each containing a seven amino acid concensus sequence at the N-terminal while the C-terminal is responsible for species specific cell death, usually by permeating the cell wall and necrotic cell leakage. Class IIb are so called two-peptide bacteriocins as two different peptides are required for activity. They includes the alpha enterocins and lactococcin G peptides which act as pore-forming toxins that permeates the cell membrane to give channels via a barrel-stave mechanism. This helps create an ion imbalance and leakage in the cell, leading to cell death. ClassIIc include the cyclic peptides. Here the N- and C-terminals are covalently bonded to give circular bacteriocins. They effect membrane permeability and cell wall formation on target cells. Bacteriocin AS-48 which is produced by Enterococcus faecalis (a streptococcus bacterium) shows a range of antimicrobial mechanisms against both Gram-Negative and Gram-Positive bacteria. Bacteriocin AS-48 is encoded by a pheromone responsive plasmid, pMB2 and attacks the plasma membrane where it punches pores leading to an ion imbalance, leading to leakage and cell death. The globular structure of bacteriocin AS-48 consists of five alpha helices enclosing a hydrophobic core. Class IId: These are the single peptide bacteriocins and display no post translational modifications or any pediocin like characteristics. One example is aureocin A53, which is stable under acidic pH conditions and is resistant to several proteases. Class IIe: Aureocin A70 is encoded within an 8 kb plasmid, pRJ6, and is composed of four peptides with 30 or 31 amino acid residues without an N-terminal leader sequence. It is toxic against Listeria monocytogenes, a facultative anaerobic bacterium and dangerous virulent food-borne pathogen, with 20-30 % of clinical infections resulting in death. Class III Bacteriocins: These are large heat labile bacteriocins of >10kDa. There are two subclasses. Class IIIa: These bacteriocins kill other bacterial cells by cell wall degdaration leading to cell lysis. The best known is lysostaphin, a27kDa protein that lysises many of the staphylococcus species, especially S. aureus. ClassIIIb: This subclass comprises of those bacteriocins that do not cause cell lysis. They destroy other bacterial cells by disrupting the cells membrane potential allowing for a net APT efflux. Class IV Bacteriocins: They are large, heat labile complex bacteriocins with different lipid and carbohydrate functional 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 encoded on plasmid pPI-1 on six separate genes. Nukacin ISK-1 contains three lanthioine molecules and/or three 3-methyllanthionine molecules, thus making it a lantibiotic. Type A lantibiotic proteins punch pores into the cytoplasmic membranes of sensitive cells leading to cell death as well as providing immunity proteins against self species produced lantibiotics by covalently binding free lantibiotic across the cell membrane (7). Material and Methods All work was done as per the manual. Production of Antimicrobial Peptides

Fast-Moving Consumer Goods Company in Rural Market Essay

Selecting the Market The growth of the fast-moving consumer goods (FMCG) sector is observed in many European organisations. Some companies demonstrate high results and achieve high income levels. Sometimes, leaders may need additional time and skills to show success as this business becomes fashionable and not all companies gain power that can be easily shifted to retailers (Thain

Can the five factor model explain personality?

assignment writing services Every person is unique. From being geniuses to serial killers, people and their personalities can vary in many ways. What makes a person the way he/she is, is a question that everyone would like to answered. What exactly is personality and is it the factor that makes everyone different? In an attempt to solve this dilemma, there is a need for clear definitions. Personality is generally defined as the ‘distinctive and relatively stable pattern of behavior, thoughts, motives and emotions that characterize an individual’, including a wide range of human behavior, conscious or unconscious ((Wade and Tavris, 2006). It is widely agreed upon that personality originates from within a person, although, a few argue that external and social factors can also be used to study personality. Many theories, that attempt to define personality and build a model around this abstract concept, are used as a tool to speculate and offer guidelines (Ewen, 2003). Many psychologists came up with theories that attempt to define personality types. According to Gordon Allport, most people have a few central traits that can be used to characterize them and have further secondary traits that are more changeable. Raymond Cattel studied this by using a statistical method called factor analysis and came up with the 16 Personality Factors. Eysenck came up with the PEN (psychoticism, extroversion, neuroticism) model, which promoted just three factors. Nowadays, most modern psychologists agree on five central factors, known as the Big Five or the Five Factor Model (FFM), which form a cluster of personality traits that divide people into the following personality types: Extroversion vs. introversion, neuroticism vs. emotional stability, agreeableness vs. antagonism, conscientiousness vs. impulsiveness, openness to experience vs. resistance to new experience. Extroversion vs. introversion explains the level to which people are sociable or shy. Extroverts are engaged with the outside world, are full of energy, like to talk and get attention and are assertive. Introverts are low key, like to be alone and need less simulation. In neuroticism, people experience anxiety and negative emotions. They are emotionally reactive as compared to people low in neuroticism, who are calm and emotionally stable. Agreeableness vs. antagonism describes the good nature or the irritableness of people. Agreeable people strive for social harmony and get along well with people. Antagonistic people, on the other hand, are disagreeable, skeptical and uncooperative. Conscientiousness people are responsible and dependable, whereas, impulsive people are rash and fickle. People are open to experiences if they are curious and creative, but conforming and unimaginative people are resistant to new experiences. Being able to define human personality has been a major challenge for psychologists and the five factor model (FFM) has emerged as a distinct personality dimension and is central in describing personality variations within mentally stable people. It has integrated and systemized wide ranging concepts and measures using various assessment methods and case studies (McCrae and Costa, 1999). The model is also supported by many factor-analytic studies and research has been conducted on diverse people and over large time periods, leading to the observation that the Big Five remain constant and stable over a person’s lifetime, especially, after the age of thirty. The five-factor model is also consistent with other models such as Eysenck’s PEN model, Catell’s 16 Factor Model and other psychological theories. Psychologists are also trying to establish a ‘Taxanomy of personality’ so people can easily be described using the sliding scales of the 5 variable of the FFM. According to Digman, the FFM has ‘given a useful set of very broad dimensions that characterize individual differences. These dimensions can be measured with high reliability and impressive validity’ and it ‘provides a good answer to the question of personality structure’ (Digman, 1990). Digman conducted studies in Japan, Philippines and Germany and states that the model is applicable cross culturally and does not fail when faced with linguistic barriers. Differences within the sexes have also been taken into account and males are shown to score higher on extraversion and conscientiousness, and females on neuroticism and agreeableness. The FFM has also been useful in predicting job performance; conscientious and extravert people perform better at work than people with neuroticism, and agreeableness correlates negatively with job performance in a leadership role. Conscientiousness is also seen as a predictor of academic performance and openness to experience is an unrelated factor (Neubert). Although these simple categorizations seem very appealing in trying to define personality, there is another side to the picture that examines the limitations of the model. It is argued that the model is not really a theory of personality as a good theory must adequately explain the system of personality. It can, therefore, more aptly be called a trait theory (McCrae and Costa, 1999). Even though the model has convergent validity, it cannot be claim to also have construct validity, as judgments can converge without being correct (Davis and Millon, 1993). According to McAdams, the FFM is not really a theory but a list of explanatory variable useful in identifying and classifying personality traits. He says the variables are too broad and, in many situations, cannot anticipate behavior. Establishing the universality of the FFM has also been called into question. A research showed that in Spanish, seven factors were required to explain personality dimensions and in Italy, only three were needed (Wade and Tavris, 2006). Moreover, the five-factor model does not take into account or explain the part of personality that is different for every person. It requires speculation to interpret individual behavior from personality profiles of people. Even in the context of work environment, it has been argued that the five factor model is not enough to predict performance. Factors such as cognitive ability, emotional intelligence and creativity add a lot to the value of an employee. Transformational leadership and job satisfaction also add a lot to the job performance of an individual. It does not explain the motivation behind becoming a leader or explain how traits interact with the environment to produce leadership qualities (Chamorro-Premuzic, 2007). A model has limited importance if it cannot be applied and according to Davis and Millon, the FFM model has many weaknesses when applied in the clinical domain as many traits involved in disorders are missing, hence, it is of more use in the academic and experimental context (Davis and Millon, 1993). Being restricted by the trait hierarchy is not advisable since there is limited information regarding personality pathology already. Other levels of trait hierarchy also help in providing information useful in clinical application. Another empirical study concluded that even though the FFM captured a significance variance for several personality disorders, it significantly predicted only 5 of the 11 disorders because of wide and intangible characterizations (Clark, 1993). Theoretically, the model has been questioned on many aspects. McAdams critiques the model on the lack of causal explanations of human behavior and experience. He believes it describes the ‘psychology of a stranger’ as it describes people one knows nothing about, failing to describe the hidden aspects of personality. Behavior might not predict personality accurately as many people do not behave in accordance to their personalities in all situations. It is said that personality is an illusion and people only behave in accordance to the social context. According to Taylor

Westcliff University Computer Science Ip Address and Subnet Mask Essay

Westcliff University Computer Science Ip Address and Subnet Mask Essay.

I’m working on a computer science question and need an explanation to help me learn.

You have been hired by a small company to a new network that will need 19 subnets with eachsubnet needing 91 IP Addresses. Show the IP address range and full subnet mask on the 3 rdvalid subnet (you must also show all math that led to your final calculations.Depending on your class of network address, you must choose the correct network addressbelow:A= include theory introduction to ip address, subnet and asks. If possible an example on Case Study.
Westcliff University Computer Science Ip Address and Subnet Mask Essay

APA Style Research Paper

APA Style Research Paper. I’m trying to learn for my Psychology class and I’m stuck. Can you help?

For this discussion, refer to the two articles, one qualitative and one quantitative, that you found in the Capella library. Use the Article Analysis Worksheet (given in the resources) to prepare for this discussion. Create a narrative summary of the articles based on information gleaned using the worksheet.
Discuss the different sections of each article with regard to how they fit into the required sections of an APA-style research paper:

Literature Review.

Did each article have each of these sections? What sort of information was found in each? Were there differences in the type of information found in the two different articles, or the way it was presented?
Note: Use the Article Analysis Worksheet to prepare your discussion post but do not post the worksheet to your discussion thread. Instead, use the information you gain in the analysis to craft a narrative of the findings to post to the discussion.
APA Style Research Paper

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