Effects of modifications to retain protozoa in continuous-culture fermenters on ruminal fermentation, microbial populations, and microbial biomass assessed by two different methods.

Cabeza Luna, I. and Carro Travieso, Maria Dolores and Fernández Yepes, J. and Molina Alcaide, Eduarda (2018). Effects of modifications to retain protozoa in continuous-culture fermenters on ruminal fermentation, microbial populations, and microbial biomass assessed by two different methods.. "Animal Feed Science and Technology" (n. 240); pp. 117-127. ISSN 0377-8401. https://doi.org/10.1016/j.anifeedsci.2018.04.004.

Description

Title: Effects of modifications to retain protozoa in continuous-culture fermenters on ruminal fermentation, microbial populations, and microbial biomass assessed by two different methods.
Author/s:
  • Cabeza Luna, I.
  • Carro Travieso, Maria Dolores
  • Fernández Yepes, J.
  • Molina Alcaide, Eduarda
Item Type: Article
Título de Revista/Publicación: Animal Feed Science and Technology
Date: June 2018
ISSN: 0377-8401
Subjects:
Freetext Keywords: Continuous-culture fermenters; Filter; Microbial DNA; Protozoa; Rumen fermentation; Sponge
Faculty: E.T.S. de Ingeniería Agronómica, Alimentaria y de Biosistemas (UPM)
Department: Producción Agraria
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

An important limitation of continuous-culture fermenters is their inability of maintaining microbial populations similar to those observed in the rumen, especially protozoa numbers, which usually decrease markedly or even disappear. Two approaches (a polyurethane-sponge (SP) and a filter system (FIL) for additionally retaining protozoa were tested in continuous culture system already designed to retain protozoa (Muetzel et al., 2009), and their effects on microbial populations, fermentation parameters and microbial biomass were assessed. Two 14-day incubation runs were carried out with 6 fermenters, and in each run two fermenters were randomly assigned to each of the experimental treatments (control, SP and FIL). Total protozoa numbers assessed by microscopic counting were 1.7 and 2.1 times greater in SP and FIL fermenters than in control ones on day 14, although differences did not reach the significance level (P = 0.855). Protozoal DNA concentration on day 14 were 1.6 and 1.4 times greater in SP and FIL fermenters, respectively, than in control ones, but differences were not significant (P = 0.524). Results from protozoal DNA concentrations determined in each fermenter on the different sampling days (n = 48) were positively correlated (P < 0.001) with the numbers of total (r = 0.826), entodiniomorphid (r = 0.824) and holotrich (r = 0.675) protozoa determined by microscopic counting, indicating that both methods are valid to assess protozoa populations. The proportion of holotrich in FILfermenters was relatively constant over the incubation period (ranging from 10.5 to 13.3% of total protozoa), but decreased with time in control (from 10.9% at day 2 to 6.7% at day 14) and SP (from 10.9 to 6.9%) fermenters. Neither the bacterial DNA concentration nor the relative abundance of fungal and archaeal DNA were influenced by any of the modifications tested, but values changed over the sampling period (days 10–14). Bacterial DNA concentration increased (P < 0.001) from day 10 to 14 in all fermenters, whereas the relative abundance of fungal and archaeal DNA decreased (P < 0.001). The tested modifications did not affect (P > 0.05) fermentation parameters, which reached a steady-state after 6 days of incubation. Values of microbial biomass determined using purine bases as a microbial marker were significantly correlated with the amount of bacterial plus protozoal DNA (r = 0.794; P = 0.002; n = 12) in each fermenter. In conclusion, the two tested modifications increased the protozoa numbers in continuous-culture fermenters, and the FIL allowed maintaining a proportion of holotrich protozoa similar to that in the ruminal fluid used as inoculum.

Funding Projects

TypeCodeAcronymLeaderTitle
Government of SpainAGL2011-22628UnspecifiedUnspecifiedEstudio de la microbiota en sistemas in vitro de simulación de la fermentación ruminal (cultivos no renovados, fermentadores rusitec y fermentadores de flujo continuo)

More information

Item ID: 54800
DC Identifier: http://oa.upm.es/54800/
OAI Identifier: oai:oa.upm.es:54800
DOI: 10.1016/j.anifeedsci.2018.04.004
Official URL: https://www.sciencedirect.com/science/article/pii/S0377840118300403?via%3Dihub
Deposited by: Memoria Investigacion
Deposited on: 08 May 2019 12:49
Last Modified: 01 Jul 2019 22:30
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