Agustín Corral-Luna

Genome Sequence of Citrobacter sp. CtB7.12, Isolated from the Gut of the Desert Subterranean Termite Heterotermes aureus

ABSTRACT The draft genome of Citrobacter sp. CtB7.12, isolated from termite gut, is presented here. This organism has been reported as a cellulolytic bacterium, which is biotechnologically important because it can be used as a gene donor for the ethanol and biofuel industries.

Short chain nitrocompounds as a treatment of layer hen manure and litter; effects on in vitro survivability of Salmonella, generic E. coli and nitrogen metabolism.

ABSTRACT The current study was conducted to assess the bactericidal effectiveness of several nitrocompounds against pathogens in layer hen manure and litter. Evidence from an initial study indicated that treatment of layer hen manure with 12 mM nitroethane decreased populations of generic E. coli and total coliforms by 0.7 and 2.2 log10 colony forming units (CFU) g−1, respectively, after 24 h aerobic incubation at ambient temperature when compared to untreated populations. Salmonella concentrations were unaffected by nitroethane in this study. In a follow-up experiment, treatment of 6-month-old layer hen litter (mixed with 0.4 mL water g−1) with 44 mM 2-nitroethanol, 2-nitropropanol or ethyl nitroacetate decreased an inoculated Salmonella typhimurium strain from its initial concentration (3 log10 CFU g−1) by 0.7 to 1.7 log10 CFU g−1 after 6 h incubation at 37°C in covered containers. After 24 h incubation, populations of the inoculated S. Typhmiurium in litter treated with 44 mM 2-nitroethanol, 2-nitropropanol, ethyl nitroacetate or nitroethane were decreased more than 3.2 log10 CFU g−1 compared to populations in untreated control litter. Treatment of litter with 44 mM 2-nitroethanol, 2-nitropropanol, ethyl nitroacetate decreased rates of ammonia accumulation more than 70% compared to untreated controls (0.167 µmol mL−1 h−1) and loses of uric acid (< 1 µmol mL−1) were observed only in litter treated with 44 mM 2-nitropropanol, indicating that some of these nitrocompounds may help prevent loss of nitrogen in treated litter. Results warrant further research to determine if these nitrocompounds can be developed into an environmentally sustainable and safe strategy to eliminate pathogens from poultry litter, while preserving its nitrogen content as a nutritionally valuable crude protein source for ruminants.

Effect of sole or combined administration of nitrate and 3-nitro-1-propionic acid on fermentation and Salmonella survivability in alfalfa-fed rumen cultures in vitro

Ruminal methanogenesis is a digestive inefficiency resulting in the loss of dietary energy consumed by the host and contributing to environmental methane emission. Nitrate is being investigated as a feed supplement to reduce rumen methane emissions but safety and efficacy concerns persist. To assess potential synergies of co-administering sub-toxic amounts of nitrate and 3-nitro-1-propionate (NPA) on fermentation and Salmonella survivability with an alfalfa-based diet, ruminal microbes were cultured with additions of 8 or 16mM nitrate, 4 or 12mM NPA or their combinations. All treatments decreased methanogenesis compared to untreated controls but volatile fatty acid production and fermentation of hexose were also decreased. Nitrate was converted to nitrite, which accumulated to levels inhibitory to digestion. Salmonella populations were enriched in nitrate only-treated cultures but not in cultures co- or solely treated with NPA. These results reveal a need for dose optimization to safely reduce methane production with forage-based diets.

Isolation and characterization of yeasts from fermented apple bagasse as additives for ruminant feeding

Solid-state fermentation can be used to produce feeds for ruminants, which can provide an enriched population of yeasts to improve ruminal fermentation. Fermentation of apple bagasse was performed to obtain a yeast-rich product, with the objective of isolating, identifying, and characterizing yeast strains and testing their capability to enhance in vitro ruminal fermentation of fibrous feeds. Yeasts were isolated from apple bagasse fermented under in vitro conditions, using rumen liquor obtained from cannulated cows and alfalfa as a fibrous substrate. A total of 16 new yeast strains were isolated and identified by biochemical and molecular methods. The strains were designated Levazot, followed by the isolate number. Their fermentative capacity was assessed using an in vitro gas production method. Strain Levazot 15 (Candida norvegensis) showed the greatest increase in gas production (p < 0.05) compared with the yeast-free control and positively affected in vitro ruminal fermentation parameters of alfalfa and oat straw. Based on these results, it was concluded that the Levazot 15 yeast strain could be potentially used as an additive for ruminants consuming high-fiber diets. However, further studies of effects of these additives on rumen digestion, metabolism, and productive performance of ruminants are required.

Draft Genome Sequences for Five Strains of Trabulsiella odontotermitis, Isolated from Heterotermes sp. Termite Gut

ABSTRACT Trabulsiella odontotermitis represents a novel species in the genus Trabulsiella with no complete genome reported yet. Here, we describe the draft genome sequences of five isolates from termites present in the north of Mexico, which have an interesting pool of genes related to cellulose degradation with biotechnological application.

Effects of repeated-low level sodium chlorate administration on ruminal and fecal coliforms in sheep

Abstract The objective of this study was to evaluate the efficacy of oral sodium chlorate administration on reducing total coliform populations in ewes. A 30% sodium chlorate product or a sodium chloride placebo was administered to twelve lactating Dorper X Blackbelly or Pelibuey crossbred ewes averaging 65 kg body weight. The ewes were adapted to diet and management. Ewes were randomly assigned (4/treatment) to one of three treatments which were administered twice daily by oral gavage for five consecutive days: a control (TC) consisting of 3 g sodium chloride/animal/d, a T3 treatment consisting of 1.8 g of sodium chlorate/animal/d, and a T9 treatment consisting of 5.4 g sodium chlorate/animal/d; the latter was intended to approximate a lowest known effective dose. Ruminal samples collected by stomach tube and freshly voided fecal samples were collected daily beginning 3 days before treatment initiation and for 6 days thereafter. Contents were cultured quantitatively to enumerate total coliforms. There were no significant differences in total coliform numbers (log10 cfu/g) in the feces between treatments (P = 0.832). There were differences (P < 0.02) in ruminal coliform counts (log10 cfu/mL) between treatments (4.1, 4.3 and 5.0 log10/mL contents in TC, T3 and T9 Treatments, respectively) which tended to increase from the beginning of treatment until the 5th day of treatment (P < 0.05). Overall, we did not obtain the expected results with oral administration of sodium chloride at the applied doses. By comparing the trends in coliform populations in the rumen contents in all treatments, there was an increase over the days. The opposite trend occurred in the feces, due mainly to differences among rumen contents and feces in ewes administered the T9 treatment (P = 0.06). These results suggest that the low chlorate doses used here were suboptimal for the control of coliforms in the gastrointestinal tract of ewes.