Cuero R G
Prairie View A & M University, Texas A & M University Systems, CARC, 77446, USA.
EXS. 1999;87:315-33. doi: 10.1007/978-3-0348-8757-1_23.
The objective of this chapter is to present fundamental factors (e.g. intrinsic and extrinsic) influencing chitosan as antimicrobial agent, for effective practical application. The antimicrobial activity of chitosan is well observed on a wide variety of micro-organisms including fungi, algae and some bacteria. However, the antimicrobial action is influenced by intrinsic and extrinsic factors such as the type of chitosan (e.g. plain or derivative); degree of chitosan polymerization; host natural nutrient constituency; substrate chemical and/or nutrient composition; and environmental conditions (e.g. substrate water activity (Aw) and/or moisture). Although both plain and derivative chitosans are effective as antimicrobial agents, there is a differential effect between them. Their differential antimicrobial effect is mainly exhibited in live host plants; thus the antifungal effect of N-carboxymethyl chitosan (NCMC) is different in vegetable as compared with graminea host. At the same time, pentamer and heptamer chitosan units seem to have better antifungal action than larger units. Chitosan antimicrobial action is more immediate on fungi and algae, followed by bacteria; the chitosan site of action is at the microbial cell wall.
本章的目的是介绍影响壳聚糖作为抗菌剂的基本因素（如内在因素和外在因素），以便其能得到有效的实际应用。壳聚糖对包括真菌、藻类和一些细菌在内的多种微生物都有明显的抗菌活性。然而，抗菌作用受到内在和外在因素的影响，如壳聚糖的类型（如普通型或衍生物型）、壳聚糖的聚合度、宿主天然营养成分、底物化学和/或营养成分以及环境条件（如底物水分活度（Aw）和/或湿度）。虽然普通壳聚糖和壳聚糖衍生物都是有效的抗菌剂，但它们之间存在差异效应。它们的差异抗菌作用主要表现在活体宿主植物中；因此，N-羧甲基壳聚糖（NCMC）在蔬菜中的抗真菌效果与禾本科宿主植物不同。同时，五聚体和七聚体壳聚糖单元似乎比更大的单元具有更好的抗真菌作用。壳聚糖对真菌和藻类的抗菌作用更直接，其次是对细菌；壳聚糖的作用位点在微生物细胞壁。
