Beneficial Microbes, 2014 September online 2014; 5(3): 1-15
ARTICLE IN PRESS
Wageningen Academic P u b l i s h e r s
Lactobacillus-produced exopolysaccharides and their potential health benefits: a review D.A. Patten1,2* and A.P. Laws1 1Department of Chemical and Biological Sciences, University of Huddersfield, Queensgate, HD1 3DH Huddersfield, United
Kingdom; 2Centre for Liver Research, School of Immunity and Infection, University of Birmingham, B15 2TT Birmingham, United Kingdom; [email protected] Received: 19 August 2014 / Accepted: 7 October 2014 © 2014 Wageningen Academic Publishers
REVIEW ARTICLE Abstract Lactic acid bacteria, such as those of the Lactobacillus genus, naturally reside within the microbiota of the human body and have long been used as starter cultures and probiotic enhancers in fermented foods, such as fermented drinks, yoghurts and cheeses. Many of the beneficial qualities of these bacteria have traditionally been associated with the bacteria themselves, however, a recent spate of studies have demonstrated a wide variety of biological effects exhibited by lactobacilli-produced exopolysaccharides which could, theoretically, confer a range of local and systemic health benefits upon the host. In this review, we discuss the production of exopolysaccharides within the Lactobacillus genus and explore their potential as beneficial bioactive compounds. Keywords: probiotics, EPSs, immunomodulation
1. Introduction Lactobacilli are a large heterogeneous group of Grampositive, facultative anaerobic bacteria that belong to the Firmicutes phylum (Lebeer et al., 2008; Wells, 2011). The Lactobacillus genus is so-named as its members are cells of bacilliform morphology which produce lactic acid as the major end-product in their metabolism of lactose and other fermentable carbohydrates (Slattery et al., 2010). In addition to a carbohydrate carbon source, lactobacilli also require a complex mixture of amino acids, peptides, fatty acids, esters, salts, nucleic acids derivatives and vitamins to sustain their growth (Kandler and Weiss, 1986). However, despite their fastidious nutritional requirements, lactobacilli have been found to inhabit an eclectic range of environmental niches, from water, soil and sewage to the commensal microbiota of plants and the human oral, vaginal and intestinal cavities (Stiles and Holzapfel, 1997). Indeed, lactobacilli are one of predominant genera of the human vaginal microbiota (Ma et al., 2012; Redondo-Lopez et al., 1990). However, within the human intestinal microbiota, lactobacilli are present in extremely variable, but relatively low numbers, representing just 0.01-0.6% of total faecal bacteria (Kimura et al., 1997; Sghir et al., 2000). Despite their low abundance in the
intestinal microbiota, it is apparent that lactobacilli play an important role in normal intestinal homeostasis as levels of lactobacilli are significantly reduced in inflammatory bowel disease (IBD) (Pathmakanthan, 1999; Zhang et al., 2007), but oral administration of lactobacilli can ameliorate the inflammation associated with this chronic disease (Gionchetti et al., 2000; Zocco et al., 2006). Therefore, it is unsurprising that lactobacilli were granted the Qualified Presumption of Safety (QPS) (EFSA, 2007) and are consequently found in a wide range of fermented food products, either as members of the natural bacterial content or as commercially-administered probiotic cultures (Bernardeau et al., 2006; Turpin et al., 2010). Additionally, the ingestion of live cultures of lactobacilli by healthy individuals can artificially elevate the low numbers which naturally reside within the intestine (Tannock et al., 2000). The term probiotic, is derived from the Greek words meaning ‘for life’ (Schrezenmeir and De Vrese, 2001), and was originally coined to describe ‘substances secreted by one microorganism which stimulate the growth of another’ (Lilly and Stillwell, 1965). Subsequently, the probiotic idiom was often used in the context of bacteria-containing animal feeds, and the definition evolved to ‘organisms and substances which contribute to intestinal microbial
ISSN 1876-2833 print, ISSN 1876-2891 online, DOI 10.3920/BM2014.01171
ARTICLE IN PRESS
Wageningen Academic P u b l i s h e r s
Lactobacillus-produced exopolysaccharides and their potential health benefits: a review D.A. Patten1,2* and A.P. Laws1 1Department of Chemical and Biological Sciences, University of Huddersfield, Queensgate, HD1 3DH Huddersfield, United
Kingdom; 2Centre for Liver Research, School of Immunity and Infection, University of Birmingham, B15 2TT Birmingham, United Kingdom; [email protected] Received: 19 August 2014 / Accepted: 7 October 2014 © 2014 Wageningen Academic Publishers
REVIEW ARTICLE Abstract Lactic acid bacteria, such as those of the Lactobacillus genus, naturally reside within the microbiota of the human body and have long been used as starter cultures and probiotic enhancers in fermented foods, such as fermented drinks, yoghurts and cheeses. Many of the beneficial qualities of these bacteria have traditionally been associated with the bacteria themselves, however, a recent spate of studies have demonstrated a wide variety of biological effects exhibited by lactobacilli-produced exopolysaccharides which could, theoretically, confer a range of local and systemic health benefits upon the host. In this review, we discuss the production of exopolysaccharides within the Lactobacillus genus and explore their potential as beneficial bioactive compounds. Keywords: probiotics, EPSs, immunomodulation
1. Introduction Lactobacilli are a large heterogeneous group of Grampositive, facultative anaerobic bacteria that belong to the Firmicutes phylum (Lebeer et al., 2008; Wells, 2011). The Lactobacillus genus is so-named as its members are cells of bacilliform morphology which produce lactic acid as the major end-product in their metabolism of lactose and other fermentable carbohydrates (Slattery et al., 2010). In addition to a carbohydrate carbon source, lactobacilli also require a complex mixture of amino acids, peptides, fatty acids, esters, salts, nucleic acids derivatives and vitamins to sustain their growth (Kandler and Weiss, 1986). However, despite their fastidious nutritional requirements, lactobacilli have been found to inhabit an eclectic range of environmental niches, from water, soil and sewage to the commensal microbiota of plants and the human oral, vaginal and intestinal cavities (Stiles and Holzapfel, 1997). Indeed, lactobacilli are one of predominant genera of the human vaginal microbiota (Ma et al., 2012; Redondo-Lopez et al., 1990). However, within the human intestinal microbiota, lactobacilli are present in extremely variable, but relatively low numbers, representing just 0.01-0.6% of total faecal bacteria (Kimura et al., 1997; Sghir et al., 2000). Despite their low abundance in the
intestinal microbiota, it is apparent that lactobacilli play an important role in normal intestinal homeostasis as levels of lactobacilli are significantly reduced in inflammatory bowel disease (IBD) (Pathmakanthan, 1999; Zhang et al., 2007), but oral administration of lactobacilli can ameliorate the inflammation associated with this chronic disease (Gionchetti et al., 2000; Zocco et al., 2006). Therefore, it is unsurprising that lactobacilli were granted the Qualified Presumption of Safety (QPS) (EFSA, 2007) and are consequently found in a wide range of fermented food products, either as members of the natural bacterial content or as commercially-administered probiotic cultures (Bernardeau et al., 2006; Turpin et al., 2010). Additionally, the ingestion of live cultures of lactobacilli by healthy individuals can artificially elevate the low numbers which naturally reside within the intestine (Tannock et al., 2000). The term probiotic, is derived from the Greek words meaning ‘for life’ (Schrezenmeir and De Vrese, 2001), and was originally coined to describe ‘substances secreted by one microorganism which stimulate the growth of another’ (Lilly and Stillwell, 1965). Subsequently, the probiotic idiom was often used in the context of bacteria-containing animal feeds, and the definition evolved to ‘organisms and substances which contribute to intestinal microbial
ISSN 1876-2833 print, ISSN 1876-2891 online, DOI 10.3920/BM2014.01171
