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.
In many cases, the abnormal color or consistency of the semen may be the result of a possible medical cause. If the color of the semen is yellow, green or gold, it may be the result of a prostrate infection. Thick, lumpy or jelly-like ejaculation may be the result of a hormonal deficiency.Pink, red, or dark brown ejaculate can indicate the presence of blood and may result due to bleeding in the prostrate.auses of yellow semen. There are various factors that can cause changes in the color of your semen. A manâs age is one of the factors here. As men get older, they notice that the color of their semen is not as whitish as it used to be.