Poly Gamma Glutamic Acid
Bioresource Technology 79 (2001) 207±225
Review paper
The production of poly-(c-glutamic acid) from microorganisms and its various applications
Ing-Lung Shih *, Yi-Tsong Van
Department of Environmental Engineering, Da-Yeh University, 112 Shan-Jiau Road, Da-Tsuen, Chang-Hwa 51505, Taiwan, ROC
Accepted 9 April 2001
Abstract
This review article deals with the chemistry and biosynthesis of poly-(c-glutamic acid) (c-PGA) produced by various strains of
Bacillus. Potential applications of c-PGA as thickener, cryoprotectant, humectant, drug carrier, biological adhesive, ¯occulant, or heavy metal absorbent, etc. with biodegradability in the ®elds of food, cosmetics, medicine and water treatments are also reviewed. Ó 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Poly-c-glutamic acid; c-PGA; Biosynthesis; Industrial applications
1. Introduction
Poly-c-glutamic acid (c-PGA) is an unusual anionic, naturally occurring homo-polyamide that is made of D and L -glutamic acid units connected by amide linkages between a-amino and c-carboxylic acid groups (Fig. 1).
It was ®rst discovered by Ivnovics and co-workers a (Ivnovics and Bruckner, 1937; Ivnovics and Erds, a a o 1937) as a capsule of Bacillus anthracis which was released into the medium upon autoclaving or upon aging and autolysis of the cells. It is also well known that the mucilage of ``natto'' (fermented soybeans, a traditional food in Japan) is a mixture of polyglutamic acid and fructan produced by Bacillus natto Sawamura
(Sawamura, 1913; Fujii, 1963). Since Bovarnick (1942) showed that c-PGA was freely secreted into the growth medium of Bacillus subtilis as a product of fermentation, several Bacillus species have been shown to produce c-PGA outside the cells. (Cheng et al., 1989; Goto and Kunioka, 1992; Hara et al., 1982a,b; Housewright,
1962; Kubota et al., 1993a,b; Murao, 1969; Thorne et al., 1954; Troy, 1973). In addition, c-linked glutamic acid polymers have also
Review paper
The production of poly-(c-glutamic acid) from microorganisms and its various applications
Ing-Lung Shih *, Yi-Tsong Van
Department of Environmental Engineering, Da-Yeh University, 112 Shan-Jiau Road, Da-Tsuen, Chang-Hwa 51505, Taiwan, ROC
Accepted 9 April 2001
Abstract
This review article deals with the chemistry and biosynthesis of poly-(c-glutamic acid) (c-PGA) produced by various strains of
Bacillus. Potential applications of c-PGA as thickener, cryoprotectant, humectant, drug carrier, biological adhesive, ¯occulant, or heavy metal absorbent, etc. with biodegradability in the ®elds of food, cosmetics, medicine and water treatments are also reviewed. Ó 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Poly-c-glutamic acid; c-PGA; Biosynthesis; Industrial applications
1. Introduction
Poly-c-glutamic acid (c-PGA) is an unusual anionic, naturally occurring homo-polyamide that is made of D and L -glutamic acid units connected by amide linkages between a-amino and c-carboxylic acid groups (Fig. 1).
It was ®rst discovered by Ivnovics and co-workers a (Ivnovics and Bruckner, 1937; Ivnovics and Erds, a a o 1937) as a capsule of Bacillus anthracis which was released into the medium upon autoclaving or upon aging and autolysis of the cells. It is also well known that the mucilage of ``natto'' (fermented soybeans, a traditional food in Japan) is a mixture of polyglutamic acid and fructan produced by Bacillus natto Sawamura
(Sawamura, 1913; Fujii, 1963). Since Bovarnick (1942) showed that c-PGA was freely secreted into the growth medium of Bacillus subtilis as a product of fermentation, several Bacillus species have been shown to produce c-PGA outside the cells. (Cheng et al., 1989; Goto and Kunioka, 1992; Hara et al., 1982a,b; Housewright,
1962; Kubota et al., 1993a,b; Murao, 1969; Thorne et al., 1954; Troy, 1973). In addition, c-linked glutamic acid polymers have also