For as long as air is prevented from entering the silo or container, relatively little occurs. Most micro-organisms of phase 2 slowly decrease in numbers. Some acid-tolerant micro-organisms survive this period in an almost inactive state; others, such as clostridia and bacilli, survive as spores. Only some acid-tolerant proteases and carbohydrates and some specialized micro-organisms, such as Lactobacillus buchneri, continue to be active at a low level. The activity of L. buchneri will be discussed in more detail later in this paper.