Both Gram-positive and Gram-negative bacteria commonly have a surface layer called an S-layer. In Gram-positive bacteria, the S-layer is attached to the peptidoglycan layer. Gram-negative bacteria's S-layer is attached directly to the outer membrane). Specific to Gram-positive bacteria is the presence of teichoic acids in the cell wall
However, there are cases where the color may appear yellowish, sometimes referred to as âyellow spermâ or âyellow semenâ. The cause of yellow sperm is uncertain but it is believed that it can be caused by infection, or foods which are rich in sulfur such as garlic and onions.Another possible cause for yellow semen could be the natural thickening of semen; especially if you have not ejaculated for quite some time.he cause of yellow sperm is uncertain but it is believed that it can be caused by infection, or foods which are rich in sulfur such as garlic and onions.
When one refers to sperm color, he is usually referring to the color of semen. Usually, semen is white or grayish in color, due to the large amount of proteins present in the secretions. Yellow may also be a normal sperm color for some men.This can occur when the ejaculate contains a large quantity of dead sperm.ealthy semen is typically white or gray to clear in color. Green semen is often an indicator of a prostate infection, which could cause abdominal pain. Certain sexually transmitted diseases may cause sperm to be yellow or green.