It is c.a decrease of gravity!!
The answer to this question would be: by producing buffer
The pH of optimal growth of bacteria might be different. Some bacteria can grow in an acid condition called acidophile, other live in base condition called alkaliphiles and the rest live in neutral pH condition called neutrophiles. The bacteria can maintain their internal pH by producing acid, base or buffer. If the surrounding pH is too acid, the bacteria can reduce the H+ concentration by producing base. If the condition is too alkali/base, the bacteria can produce acid by doing fermentation.
These viral particles, also known as virions, consist of two or three parts: the genetic material made from either DNA or RNA, long molecules that carry genetic information, a protein coat, called the capsid, which surrounds and protects the genetic material. Hope this helped :)