Sir Alexander Fleming, a Scottish researcher, is credited with the discovery of penicillin in 1928.

In 1928, Alexander Fleming was investigating the properties of Staphylococci. One day, he observed that the culture of Staphylococci was contaminated with fungus and that colonies of the culture surrounding the fungus had been destroyed. 
Fleming grew the mold in a pure culture and found that it produce a substance that killed a number of disease-causing bacteria. He identified the mold (fungus) as being from the Penicillium genus and named the substance it released Penicillin. He investigated its positive antibacterial effect on many organisms and noticed that it affected bacteria such as Staphylococci and many other Gram-positive pathogens that cause scarlet fever, pneumonia, meningitis, diphtheria but not typhoid fever caused by Gram-negative bacteria.

Penicillin is a group of antibiotics derived from Penicillium fungi. The discovery of penicillin is attributed to Alexander Flemming in 1928.
Salman Waksman discovered streptomycin
Burkholder discovered Pfiesteria, which is a genus of heterotrophic dinoflagellates
Eugene Dubois was the first person to ever deliberately search for fossils of human ancestors
So, the correct answer is 'Fleming'

Selman Waksman, the microbiologist who discovered streptomycin, first used the word "antibiotic" in 1943. 

• Alexander Fleming was working on a Bacterial culture of Staphylococcus to studying the action of lysozyme and its role in the fighting of the infection.
• While he was working with the culture he noticed that the bacterial culture's growth is inhibited due to the growth of fungal infection on it.
• The fungus that infected the culture was  Penicillium notatum , whose secretion was later to be discovered as antibiotic penicillin.
  
• So the answer Penicillium notatum is correct.
  

• Alexander Fleming was working with a bacteria to study the action of lysozyme and its role in the fighting of the infection in the human body.
• The bacterial culture that he was working on was of Staphylococcus 
• Due to some fault, the bacterial culture Fleming was working on developed a fungal infection of Penicillium notatum which inhabited the growth of the bacteria in the culture.
• The secretion which was released by the fungus was called mold juice by Fleming but later he named it as penicillin after the name of the organism which secretes it.
• So the answer Staphylococcus is correct.
  

• Discovery of penicillin antibiotic by Fleming was an accidental discovery.
• Fleming was working with different bacterial strains to study the effect of lysozyme in fighting of bacterial infection in human body.
• In his lab there were many petri dish containing different strains of bacteria, he observed that one of the petridishes containing the strain for bacteria  Staphylococcus was infected by the growth of a fungus
• This fungus growing along with the bacterial colony inhibited the growth of the bacterial colony
• On further observation Fleming saw that the chemical substances secreted by the mold inhibited the bacterial growth. He named it Penicillin after the name of the organism ie Penicillium notatum
• So, the correct answer is Penicillium notatum 
  

• In September 1928 when Alexander Fleming observed his Petri dishes of the bacterial culture he notice that the culture of bacteria Staphylococcus has a mold growing over it which has inhabited its growth in that area.
• Upon observing he found that the mold was a strain of fungus Penicillium notaum and its was secreting some substance which inhibited the growth of the bacteria.
• He named it penicillin after the organism from which it is secreted.
• So the answer Alexander Fleming who discovered the first antibiotic penicillin is correct.
  

The discovery of Penicillin was a case of serendipity and it was observed on a culture plate of Staphylococcus aureus that was contaminated by a fungus species. 

• Sutton deduced that chromosomes are the basis of heredity and that the reduction of chromosomes in meiosis is directly related to Mendel's laws of inheritance.
• Thomas Hunt Morgan described the phenomenon of linkage and crossing over. Morgan imagined that genes on chromosomes were similar to pearls on a string, in other words, they were physical objects. The closer two genes were to one another on a chromosome, the greater their chance of being inherited together. In contrast, genes located farther away from one another on the same chromosome were more likely to be separated during recombination. Therefore, Morgan correctly proposed that the strength of linkage between two genes depends upon the distance between the genes on the chromosome. This proposition became the basis for construction of the earliest maps of the human genome.
• James Dewey Watson discovered the structure of DNA in 1953 with Francis Crick.
• Scottish bacteriologist Alexander Fleming accidentally discovered the antibiotic in 1928, when he came back from a vacation and found that a green mold called Penicillium notatum had contaminated Petri dishes in his lab and were killing some of the bacteria he’d been growing.

Antibiotic is a medicine which inhibits the growth of microbes. This term was coined by Selman Waksman. They are produced by many bacteria, fungi, and other microorganisms. Some of them increase the activity of mast cell resulting into allergy. They are specific for the disease.

(A)Cristian Haneen verified the Purification of enzyme zennet.

Selman Waksman, the microbiologist who discovered streptomycin, first used the word "antibiotic" in the medical sense in 1943. 

• Antibiotics are antimicrobials that are released by bacteria, fungi or molds naturally or are synthesized artificially that are capable of killing or inhibiting competing microbial species. They are therefore antimicrobial substances and not entire microorganisms that are used. 
• In 1928 penicillin, the first true antibiotic was discovered by Alexander Fleming from colonies of Staphylococcus bacteria. However, its full potential as an antibiotic was established by Florey and Chain. Howard Florey, Ernst Chain, and Sir Alexander Fleming received the Nobel prize for their work on penicillin in 1945. 
• So, the correct answer is '(i) only'.

Penicillin, one of the first and still one of the most widely used antibiotic agents, derived from the Penicillium mold. Streptomycin is produced from Streptomyces griseus bacteria. Ampicillin and Amoxicillin are synthetic antibiotics. So the above-selected option is correct 

Penicillin was discovered in London in September of 1928 by Dr. Alexander Fleming, the bacteriologist on duty at St. Mary’s Hospital. The discovery of penicillin has often been described as a miracle drug because prior to the discovery of penicillin, death could occur in very trivial injuries and diseases.