Elsevier

Carbohydrate Polymers

Volume 184, 15 March 2018, Pages 435-444
Carbohydrate Polymers

Paenibacillus panacisoli enhances growth of Lactobacillus spp. by producing xylooligosaccharides in corn stover ensilages

https://doi.org/10.1016/j.carbpol.2017.12.044Get rights and content

Highlights

Abstract

The knowledge about the association of lignocellulosic biomass-degrading microbes with lactic acid bacteria (LAB) in ensilages is still limited. Paenibacillus strains are important microbes in sustainable agriculture. Here, P. panacisoli SDMCC050309 was isolated from ensiled corn stover and used as an example to investigate the effects on LAB. This strain produced at least 7 xylanases, and two of them were purified and characterized. Temperature and pH optima were determined to be 55 °C and 8.0 for Xyn10 and 40 °C and 7.0 for Xyn11, respectively. They could degraded larch wood xylan and alkali-pretreated corn stover into xylooligosaccharides (XOS). Using the produced XOS to culture Lactobacillus brevis SDMCC050297 and L. parafarraginis SDMCC050300, both of them grew well with high level of acetic acid production. The same phenomenon was observed when co-culturing those two Lactobacillus strains with P. panacisoli SDMCC050309. Therefore, P. panacisoli enhances growth of LAB by producing XOS in corn stover ensilages.

Introduction

Ensiling is a crop preservation method based on natural lactic acid fermentation under anaerobic conditions (Gollop, Zakin, & Weinberg, 2005). It is also a complex process that involves the interaction of numerous microbial species, ultimately changing the biochemical composition of silages (McDonald, Henderson, & Heron, 1991). Among the microbial species, lactic acid bacteria (LAB) are the most important group of bacteria which convert the water soluble carbohydrates (WSC) into lactic acid and acetic acid to inhibit the undesirable microorganisms (Rooke, & Hatfield, 2003). Thus, homofermentative as well as heterofermentative LAB species with excellent performance, such as Lactobacillus plantarum and Lactobacillus brevis, have been used as bacterial inoculates for silages (Francisco, Richard, Glen, Glen, & Paul, 2013; Reich, & Kung, 2000). However, LAB are lacking in lignocellulosic biomass-degrading enzymes which degrade lignocellulosic component into WSC (Sun et al., 2012).

The ensiling of corn stover is gaining increasing attention due to its high nutritional value and good palatability (Pang et al., 2011). Corn stover (particular wilted corn stover) is mainly composed of cellulose, hemicellulose and lignin, but a small amount of WSC (Ribeiro et al., 2015), which limits the growth of LAB during ensilage. Hemicellulose is the second abundant organic materials and takes up 25.1% dry matter of corn stover (Lizasoain et al., 2017), and xylan is the most important hemicellulose component (Liao et al., 2014). Xylanases are key enzymes for degradation of the backbone of xylan by hydrolyzing β-1, 4-xylosidic linkages between two d-xylopranosyl residues, and release of WSC (Shallom, & Shoham, 2003; Yan, Hao, Jiang, Zhai, & Chen, 2009). Hence, xylanases are often used as additives in ensilages. The hydrolysis abilities of xylanases on forage crops such as corn and alfalfa in ensilages were determined previously and they were considered as the promising candidates for increasing in vitro NDF digestibility (Lynch, Prema, Van Hamme, Church, & Beauchemin, 2014; Yang, Chen, Gao, & Li, 2001). In consequence, the fiber content of ensiled forage crops is reduced, so as to lighten the digestion burden of animals. Meanwhile, the produced WSC can promote the growth of LAB. So far, the commercial xylanases used in silage processes are from fungi, a group of aerobic microorganisms that could not grow in silage processes (Khota, Pholsen, Higgs, & Cai, 2016). The fermentation and extraction process of xylanase preparation inevitably increase costs.

Paenibacillus spp., widely distributed in soil and associated with plants roots, are important strains in sustainable agriculture biotechnology (Grady, MacDonald, Liu, Richman, & Yuan, 2016; Kämpfer et al., 2017). Owing to promoting the growth of plants and protecting plants against insect herbivores and phytopathogens, multiple species of Paenibacillus have been used in commercial biofertilizers (Weselowski, Nathoo, Eastman, MacDonald, & Yuan, 2016). Moreover, specific Paenibacillus strains also produce a variety of enzymes, including amylase, cellulases, xylanases and lipases, with potential applications in process manufacturing for food, textile, paper and biofuel (Raddadi, Cherif, Daffonchio, & Fava, 2013; Valenzuela, Diaz, & Pastor, 2014). Meanwhile, Paenibacillus strains and spores are found involving in ensilages, and the species can survive in the late phase of ensiling fermentation (Driehuis, Hoolwerf, & Rademaker, 2016; Ning et al., 2017). However, no research into the performance of these species and their enzymes in ensiling process has been conducted yet.

P. panacisoli is a newly identified facultative anaerobic bacteria (Ten et al., 2006). In this study, a strain P. panacisoli SDMCC050309 with high xylanase activities was isolated from ensiled corn stover. We characterized the xylanases properties produced by P. panacisoli SDMCC050309, and investigated the effects of this strain and its hydrolysates on L. brevis SDMCC050297 and L. parafarraginis SDMCC050300. The aim of this study is to find out the effects of xylanase-producing microbes on Lactobacillus inoculant strains in corn stover ensilages.

Section snippets

Strains, vectors, culture conditions and chemicals

To isolate bacteria with xylanase activity, LB (Luria-Bertani) medium supplementary with 0.5% larch wood xylan was used. The isolates were cultured in LB medium at 37 °C aerobically. The modified minimal medium: (g/L) K2HPO4, 1.67; KH2PO4, 0.87; NaCl, 0.05; MgSO4·7H2O, 0.1; CaCl2, 0.04; FeCl3, 0.004; Na2MoO4·2H2O, 0.005; biotin, 0.01; nicotinic acid, 0.02; pantotenic acid, 0.01; NH4Cl, 1, and supplemented with 0.1% yeast extract and 0.5% larch wood xylan (MM-LX medium) or 0.5% corn stover bran

Isolation and identification of xylan-degrading bacteria

Among all the isolates, one strain SDMCC050309 showed maximal hydrolysis zone in the plates containing larch wood xylan, suggesting it was a xylanase producer (data not shown). To identify the strain, 16S rDNA gene was amplified and sequenced. A neighbor-joining phylogenetic tree based on this sequence was constructed as shown in Fig. 1. Based on the morphological and physiological characteristics, combined with the 16S rRNA gene sequence (shared 99% sequence identity with P. panacisoli DSM

Discussion

LAB and lignocellulosic biomass-degrading microbes are naturally adhered to the plant surface (Kadivar & Stapleton, 2003). During the ensiling process, they co-exist in forage crops to carry out the fermentation. Although LAB dominate the fermentation in well-processed silage, producing the low pH conditions that to stop the growth and metabolism of other microorganisms, there are diverse microbial activities in the initial period of ensiling (Dunièrea, Sindoub, Chaucheyras-Durand, Chevallier,

Conclusion

During the ensiling process, LAB and other microorganisms co-exist in forage crops to carry out the fermentation. However, the knowledge about the association of lignocellulosic biomass-degrading microbes with the LAB is still limited. Two xylanases produced by P. panacisoli SDMCC050309 were identified and characterized. Their hydrolysis products XOS could act as carbon source for promoting the growth of L. brevis SDMCC050297 and L. parafarraginis SDMCC050300 to generate high level of acetic

Acknowledgements

This study was funded by Public Service Sectors (Agriculture) Special and Scientific Research Projects (201503134), National Natural Science Foundation of China (31471715), and National Science Foundation for Young Scientists of China (31400077).

References (45)

  • G.O. Ribeiro et al.

    Effect of fibrolytic enzymes added to a Andropogon gayanus grass silage- concentrate diet on rumen fermentation batch cultures and the artificial rumen (Rusitec)

    Animal

    (2015)
  • C.R. Santos et al.

    Molecular mechanisms associated with xylan degradation by Xanthomonas plant pathogens

    Journal of Biological Chemistry

    (2014)
  • D. Shallom et al.

    Microbial hemicellulases

    Current Opinion in Microbiology

    (2003)
  • J. Wang et al.

    In vitro fermentation of xylooligosaccharides from wheat bran insoluble dietary fiber by Bifidobacteria

    Carbohydrate Polymers

    (2010)
  • Q. Yan et al.

    Properties of a xylanase from Streptomyces matensis being suitable for xylooligosaccharides production

    Journal of Molecular Catalysis B: Enzymatic

    (2009)
  • X. Yang et al.

    Bioconversion of corn straw by coupling ensiling and solid-state fermentation

    Bioresource Technology

    (2001)
  • Y.X. Ye et al.

    A β-xylosidase hyper-production Penicillium oxalicum mutant enhanced ethanol production from alkali-pretreated corn stover

    Bioresource Technology

    (2017)
  • E. Di Marco et al.

    Raw sugarcane bagasse as carbon source for xylanase production by Paenibacillus species: A potential degrader of agricultural wastes

    Environmental Science and Pollution Research

    (2017)
  • M. Dubois et al.

    Colorimetric method for determination of sugars and related substances

    Analytical Chemistry

    (1956)
  • L. Dunièrea et al.

    Silage processing and strategies to prevent persistence of undesirable microorganisms

    Animal Feed Science and Technology

    (2013)
  • P. Falck et al.

    Xylooligosaccharides from hardwood and cereal xylans produced by a thermostable xylanase as carbon source for Lactobacillus brevis and Biofodobacterium adolescentis

    Journal of Agricultural and Food Chemistry

    (2013)
  • E. Francisco et al.

    Lactobacillus plantarum effects on silage fermentation and in vitro microbial yield

    Animal Feed Science and Technology

    (2013)
  • Cited by (16)

    • Peptide transporter-related protein 2 plays an important role in glutathione transport of Streptococcus thermophilus

      2021, Journal of Dairy Science
      Citation Excerpt :

      The peptide transporter-related protein coding genes were inactivated using an efficient and widely adopted approach in Strep. thermophilus with slight modifications (Maguin et al., 1996; Baccigalupi et al., 2000; Gopal et al., 2005; Xu et al., 2018). An internal fragment of peptide transporter-related protein coding genes was amplified using the genomic DNA of Strep.

    • Low-sugar yogurt making by the co-cultivation of Lactobacillus plantarum WCFS1 with yogurt starter cultures

      2020, Journal of Dairy Science
      Citation Excerpt :

      The content of residual sugars and metabolites in the cultures were determined by HPLC as described previously (Xu et al., 2017). All the molecular manipulations in this study were performed as described previously (Xu et al., 2018). Ex Taq polymerase, restriction enzymes, and T4 DNA ligase were used according to manual protocols (TaKaRa, Tokyo, Japan).

    • Development of strong lactose/galactose-inducible expression system for Lactobacillus plantarum by optimizing promoter

      2019, Biochemical Engineering Journal
      Citation Excerpt :

      The primers used in this study are listed in Table S2. All the molecular manipulations were performed as described previously [20]. Ex Taq polymerase, restriction enzymes and T4 DNA ligase were used according to manual protocol (TaKaRa, Tokyo, Japan).

    • Endoglucanase improve the growth of homofermentative Lactobacillus spp. in ensilages

      2019, Journal of Biotechnology
      Citation Excerpt :

      Paenibacillus panacisoli was often distributed in organic matter-rich environment, suggesting their great potential in sustainable biotechnology (Grady et al., 2016). P. panacisoli SDMCC050309, previously isolated from corn stover silages, could produce multiple lignocellulosic biomass-degrading enzymes (Xu et al., 2018). In this study, two endoglucanases were identified from the cultures of P. panacisoli SDMCC050309, and used as examples to study the effects on the growth of four silage inoculants: homofermentative L. plantarum CGMCC6888 and L. farciminis CCTCC AB2016237, and heterofermentative L. brevis SDMCC050297 and L. parafarraginis SDMCC050300.

    View all citing articles on Scopus
    View full text