中文摘要：

从土壤样品中分离和筛选到1株γ-聚谷氨酸（poly-γ-glutamic acid,γ-PGA）高产菌株C1。经形态、生理生化和16S rRNA序列分析,将C1鉴定为枯草芽孢杆菌。水培试验表明：添加γ-PGA对全养分条件下玉米幼苗生物量增长没有明显的影响,但显著提高了1/2和1/4养分条件下玉米幼苗地上部和地下部生物量。γ-PGA在各种养分条件下都能提高叶绿素相对含量（SPAD值）和根系活力,但1/2和1/4养分条件下提高作用更显著。当γ-PGA浓度低于0.30 g.L-1时,生物量和SPAD值随γ-PGA浓度增加而增加;添加γ-PGA处理的玉米根系活力始终高于对照且与γ-PGA添加量无关。本研究首次揭示了较低浓度的细菌源γ-PGA对低营养条件下玉米的生长有显著的促进作用。

英文摘要：

The strain C1,which was isolated and screened from soil samples,was confirmed to produce high amount of poly-γ-glutamic acid（γ-PGA）and identified as a Bacillus subtilis strain by morphological,physiological and biochemistry experiments and 16S rRNA gene sequence analysis.The results from hydroponic experiments showed that the bacterial γ-PGA had no effect on the increase of biomass of maize seedlings under the whole-strength of nutrients,but significantly increased above-and under-ground biomass of the seedlings under the half-and the quarter-strength of nutrients.All γ-PGA treatments increased the values of relative chlorophyll content（SPAD）and root activity,whereas the enhancement by γ-PGA was most pronounced under conditions of the half-and the quarter-strength of nutrients.The biomass and SPAD increased with the increase of γ-PGA level until the γ-PGA level was 0.30 g·L-1,while the root activity maintained higher values in all γ-PGA treatments than in the control without γ-PGA amendment and was not related to the amount of γ-PGA added.This work first indicated that the low level γ-PGA could improve the growth of maize seedlings in low nutrient conditions.