Ammonia amendment promotes high rate lactate production and recovery from semi-continuous food waste fermentation

In this study, a reliable approach using ammonia nitrogen was proposed to increase lactate production during semi-continuous food waste (FW) fermentation under mesophilic conditions. Both free ammonia nitrogen (FAN) and ammonium ion (NH₄⁺-N) were present in mesophilic reactors, with a wide FAN/NH₄⁺-N ratio variation due to the intermittent pH control. The investigation of responsible mechanisms revealed that the increased production yield of LA was associated with the acceleration of solubilization, hydrolysis, glycolysis and acidification. The presence of FAN and NH₄⁺-N in proper concentrations increased lactate production by 2.4 folds and recovered lactate production to 24.5 g COD/L from low rate control reactor (9.6 g COD/L) under mesophilic conditions. Furthermore, the microorganisms responsible for LA accumulation (Bavariicoccus, Enterococcus, Bifidobacterium and Corynebacterium) were selectively enriched, and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways associated with carbohydrate transport and LA production were enhanced in nitrogen fed reactors.

The applicability of gene sequencing and MALDI-TOF to identify less common gram-negative rods (Advenella, Castellaniella, Kaistia, Pusillimonas and Sphingobacterium) from environmental isolates

Our aim was to identify less common non-fermenting gram-negative rods during the bioremediation process. Five genera were found: Advenella, Castellaniella, Kaistia, Pusillimonas and Sphingobacterium, for a total of 15 isolates. Therefore, we evaluated the applicability of four methods currently available for bacteria identification: (1) conventional biochemical methods, (2) the VITEK^®-2 system, (3) MALDI-TOF mass spectrometry and (4) 16S rRNA gene sequencing. The biochemical methods and the VITEK^®-2 system were reliable only for the Sphingobacterium isolate and solely at the genus level. Both MALDI-TOF mass spectrometry platforms (Bruker and VITEK^® MS) did not achieve reliable identification results for any of these genera. 16S rRNA gene sequencing identified eight isolates to the species level but not to the subspecies level, when applicable. The remaining seven isolates were reliably identified through 16S rRNA gene sequencing to the genus level only. Our findings suggest that the detection and identification of less common genera (and species) that appeared at certain moments during the bioremediation process can be a challenge to microbiologists considering the most used techniques. In addition, more studies are required to confirm our results.

Microbiota characterization of a Belgian protected designation of origin cheese, Herve cheese, using metagenomic analysis

Herve cheese is a Belgian soft cheese with a washed rind, and is made from raw or pasteurized milk. The specific microbiota of this cheese has never previously been fully explored and the use of raw or pasteurized milk in addition to starters is assumed to affect the microbiota of the rind and the heart. The aim of the study was to analyze the bacterial microbiota of Herve cheese using classical microbiology and a metagenomic approach based on 16S ribosomal DNA pyrosequencing. Using classical microbiology, the total counts of bacteria were comparable for the 11 samples of tested raw and pasteurized milk cheeses, reaching almost 8 log cfu/g. Using the metagenomic approach, 207 different phylotypes were identified. The rind of both the raw and pasteurized milk cheeses was found to be highly diversified. However, 96.3 and 97.9% of the total microbiota of the raw milk and pasteurized cheese rind, respectively, were composed of species present in both types of cheese, such as Corynebacterium casei, Psychrobacter spp., Lactococcus lactis ssp. cremoris, Staphylococcus equorum, Vagococcus salmoninarum, and other species present at levels below 5%. Brevibacterium linens were present at low levels (0.5 and 1.6%, respectively) on the rind of both the raw and the pasteurized milk cheeses, even though this bacterium had been inoculated during the manufacturing process. Interestingly, Psychroflexus casei, also described as giving a red smear to Raclette-type cheese, was identified in small proportions in the composition of the rind of both the raw and pasteurized milk cheeses (0.17 and 0.5%, respectively). In the heart of the cheeses, the common species of bacteria reached more than 99%. The main species identified were Lactococcus lactis ssp. cremoris, Psychrobacter spp., and Staphylococcus equorum ssp. equorum. Interestingly, 93 phylotypes were present only in the raw milk cheeses and 29 only in the pasteurized milk cheeses, showing the high diversity of the microbiota. Corynebacterium casei and Enterococcus faecalis were more prevalent in the raw milk cheeses, whereas Psychrobacter celer was present in the pasteurized milk cheeses. However, this specific microbiota represented a low proportion of the cheese microbiota. This study demonstrated that Herve cheese microbiota is rich and that pasteurized milk cheeses are microbiologically very close to raw milk cheeses, probably due to the similar manufacturing process. The characterization of the microbiota of this particular protected designation of origin cheese was useful in enabling us to gain a better knowledge of the bacteria responsible for the character of this cheese.

Recommended minimal standards for description of new taxa of the genera Bifidobacterium, Lactobacillus and related genera

Minimal standards for the description of new cultivable strains that represent novel genera and species belonging to the genera Bifidobacterium , Lactobacillus and related genera are proposed in accordance with Recommendation 30b of the Bacteriological Code (1990 Revision): the description of novel species should be based on phenotypic, genotypic and ecological characteristics to ensure a rich polyphasic characterization. Concerning genotypic characterization, in addition to DNA G+C content (mol%) data, the description should be based on DNA–DNA hybridization (DDH), 16S rRNA gene sequence similarities and at least two housekeeping gene (e.g. hsp60 and recA) sequence similarities. DDH might not be needed if the 16S rRNA gene sequence similarity to the closest known species is lower than 97 %. This proposal has been endorsed by members of the Subcommittee on the Taxonomy of Bifidobacterium , Lactobacillus and related organisms of the International Committee on the Systematics of Prokaryotes.

Jeotgalibaca dankookensis gen. nov., sp. nov., a member of the family Carnobacteriaceae, isolated from seujeot (Korean traditional food)

A novel, Gram-stain-positive bacterium, designated strain EX-07T, was isolated from seujeot (Korean traditional food). The strain was aerobic, halotolerant and non-motile; it formed cocci that grouped into tetrads and sarcinae or formed irregular conglomerates. Growth occurred at pH 7-9, at 10-37 °C and with up to 9% NaCl. Isolate EX-07T was catalase- and oxidase-negative and used sugars and organic acids as carbon sources. The 16S rRNA gene sequence of the novel strain showed 94.2-94.5% similarity with the type strains of Trichococcus pasteurii, Trichococcus patagoniensis, Trichococcus collinsii, Trichococcus flocculiformis and Trichococcus palustris and only 92.2% with representatives of the genera Bavariicoccus, Carnobacterium and Granulicatella. Sequence similarities based on the groEL gene ranged from 81.3 to 82.8% between the novel isolate and the type strains of all species of the genus Trichococcus, and only 74.2 and 75.3% with type strains of members of the genera Bavariicoccus and Granulicatella, respectively. The G+C content of the genomic DNA was 39.6 mol%. The predominant fatty acids were C16:1ω9c, C18:1ω9c, C16:0 and C14:0. The polar lipid profile was very complex and included phosphatidylethanolamine and several unidentified aminolipids, glycolipids and phospholipids. Based on the genotypic and phenotypic results obtained in this study, it is proposed that isolate EX-07T represents a novel species of a new genus in the family Carnobacteriaceae for which the name Jeotgalibaca dankookensis gen. nov., sp. nov. is proposed. The type strain of Jeotgalibaca dankookensis is EX-07T (=KCCM 90229T=JCM 19215T).

Virgibacillus halotolerans sp. nov., isolated from a dairy product

A Gram-stain-positive, strictly aerobic, rod-shaped and weakly motile bacterium, designated WS 4627T, was isolated from a dairy product sample collected in southern Germany. Spherical to slightly ellipsoidal endospores were formed centrally or subterminally in sometimes slightly swollen sporangia. The isolate was able to grow at 8–35 °C, at pH 6.5–8.5 and with 0.5–16.5 % (w/v) NaCl. The diamino acid of the cell wall was meso-diaminopimelic acid (peptidoglycan type A1γ) and the genomic DNA G+C content was 39.1 mol%. The major menaquinone was MK-7, the cellular fatty acid profile contained major amounts of anteiso-C15 : 0 and anteiso-C17 : 0 and the major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. Strain WS 4627T was most closely related to ‘ Virgibacillus natachei’ FarD (96.5 % 16S rRNA gene sequence similarity) and ‘ Virgibacillus zhanjiangensis’ JSM 079157 (96.0 %). Based on the data presented, strain WS 4627T represents a novel species of the genus Virgibacillus , for which the name Virgibacillus halotolerans sp. nov. is proposed. The type strain is WS 4627T ( = DSM 25060T = LMG 26644T).

Domibacillus robiginosus gen. nov., sp. nov., isolated from a pharmaceutical clean room

A novel red-pigmented bacterial strain, designated WS 4628T, was isolated from a pharmaceutical clean room of a vaccine-producing company and was investigated in a taxonomic study using a polyphasic approach. The strain was Gram-stain-positive, strictly aerobic, motile, catalase-positive and produced spherical to slightly ellipsoidal endospores in rods. The genomic DNA G+C content was 44.1 mol%. The major fatty acids were anteiso-C15 : 0, iso-C15 : 0 and anteiso-C17 : 0 and the predominant quinone was MK-6. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, an unidentified phosphoglycolipid and an unidentified phospholipid. meso-diaminopimelic acid (type A1γ) was present in the cell-wall peptidoglycan and the major whole-cell sugars were glucose and ribose. The closest phylogenetic neighbours were identified as Bacillus badius ATCC 14574T (95.8 % 16S rRNA gene sequence similarity), Bacillus indicus Sd/3T (94.8 %), Jeotgalibacillus alimentarius YKJ-13T (94.8 %) and Bacillus cibi JG-30T (94.8 %). Phylogenetic, physiological, biochemical and morphological differences between strain WS 4628T and its closest relatives in the families Bacillaceae and Planococcaceae suggest that this strain represents a novel species in a new genus in the family Bacillaceae for which the name Domibacillus robiginosus gen. nov., sp. nov. is proposed; the type strain of the type species is WS 4628T ( = DSM 25058T = LMG 26645T).

Lysinibacillus meyeri sp. nov., isolated from a medical practice

A Gram-positive, oxidase- and catalase-positive, strictly aerobic and motile bacterium, designated WS 4626T, was isolated from a medical practice. Spherical endospores were formed terminally in swollen rods. The genomic DNA G+C content was 37.1 mol%. Cells contained iso-C15 : 0, anteiso-C15 : 0, iso-C17 : 1ω10c, anteiso-C17 : 0 and iso-C17 : 0 as the predominant cellular fatty acids and MK-7 and MK-6 as the major isoprenoid quinones. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol, the cell-wall peptidoglycan was type A4α, l-Lys-d-Asp and the major cell-wall sugar was xylose. The closest phylogenetic relatives were Lysinibacillus xylanilyticus XDB9T (96.7 % 16S rRNA gene sequence similarity) and Lysinibacillus odysseyi 34hs-1T (96.5 %). DNA–DNA relatedness between the isolate and L. odysseyi DSM 18869T was very low (6 %). On the basis of the data presented, strain WS 4626T represents a novel species of the genus Lysinibacillus , for which the name Lysinibacillus meyeri sp. nov. is proposed. The type strain is WS 4626T ( = DSM 25057T = LMG 26643T).

Psychroflexus halocasei sp. nov., isolated from a microbial consortium on a cheese

A novel halophilic, Gram-reaction-negative, strictly aerobic, non-motile, rod-shaped and oxidase- and catalase-positive bacterial strain, designated WCC 4520T, was isolated from a semi-hard, Raclette-type cheese. The colonies were yellow–orange; flexirubin-type pigments were not found. The strain hydrolysed gelatin, hippurate, tyrosine and Tweens 20 and 80. Optimal growth was observed with 6–8 % (w/v) NaCl, at pH 7–8 and at 27–30 °C. The genomic DNA G+C content was 33.6 mol%. In phylogenetic analysis based on 16S rRNA gene sequences, strain WCC 4520T appeared to be a member of the family Flavobacteriaceae and the closest phylogenetic neighbours were identified as Psychroflexus gondwanensis DSM 5423T (94.0 % 16S rRNA gene sequence similarity) and Psychroflexus salinarum CCUG 56752T (94.0 %). The predominant cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0, iso-C15 : 1 G and iso-C17 : 0 3-OH. The only detected quinone was MK-6 and the major polar lipids were phosphatidylethanolamine, an unidentified aminolipid and an unidentified polar lipid. Minor polar lipids and traces of polyamines were also detected. On the basis of the data presented, strain WCC 4520T represents a novel species of the genus Psychroflexus , for which the name Psychroflexus halocasei sp. nov. is proposed. The type strain is WCC 4520T ( = LMG 25857T = CCUG 59705T).

Sphingobacterium lactis sp. nov. and Sphingobacterium alimentarium sp. nov., isolated from raw milk and a dairy environment

Four non-fermenting, rod-shaped, Gram-staining-negative bacterial strains, designated WCC 4512T, WS 4555, WCC 4521T and WS 4556, were isolated from raw milk and the dairy environment. Phylogenetic analyses based on 16S rRNA and groEL gene sequences demonstrated the affiliation of the four strains to two distinct clusters within the class Sphingobacteriia , phylum ‘ Bacteroidetes ’. Strains WCC 4512T and WS 4555 showed the highest 16S rRNA gene sequence similarity to the type strain of S. daejeonense (97.3 and 97.2 %, respectively), whereas strains WCC 4521T and WS 4556 were most closely related to S. composti LMG 23401T (97.6 % 16S rRNA gene sequence similarity). The DNA G+C contents of strains WCC 4512T and WCC 4521T were 44.2 and 39.3 mol%, respectively. The major cellular fatty acids and the presence of menaquinone MK-7 as the predominant quinone for both strains WCC 4512T and WCC 4521T supported their affiliation to the genus Sphingobacterium . DNA–DNA hybridization experiments between strain WCC 4512T and S. daejeonense LMG 23402T and between strain WCC 4521T and S. composti LMG 23401T revealed DNA relatedness values of 2 % (repetition, 3 %) and 8 % (repetition, 17 %), respectively. On the basis of phenotypic and genetic properties, as well as phylogenetic distinctiveness, it is suggested that the four strains represent two novel Sphingobacterium species with strain WCC 4512T ( = DSM 22361T = LMG 25272T) as the type strain of Sphingobacterium lactis sp. nov. (WS 4555 is a reference strain of S. lactis) and strain WCC 4521T ( = DSM 22362T = LMG 25273T) as the type strain of Sphingobacterium alimentarium sp. nov. (WS 4556 is a reference strain of S. alimentarium).

Bacillus gottheilii sp. nov., isolated from a pharmaceutical manufacturing site

A novel Gram-staining-positive, rod-shaped, motile, strictly aerobic, endospore-forming bacterium, designated WCC 4585(T), was isolated from a pharmaceutical production line. The organism grew optimally at 30 °C, at pH 8 and in the presence of 0.5 % (w/v) NaCl. Oval endospores were formed subterminally and terminally in swollen sporangia. The cell-wall diamino acid was meso-diaminopimelic acid (type A1γ) and the genomic DNA G+C content was 38.7 mol%. The major menaquinone was MK-7. The cellular fatty acid profile contained major amounts of iso-C15 : 0, anteiso-C15 : 0 and anteiso-C17 : 0, and the cellular phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and aminophospholipid. The isolate was most closely related to Bacillus oceanisediminis H2(T), Bacillus infantis SMC 4352-1(T), Bacillus firmus NCIMB 9366(T), Bacillus circulans ATCC 4513(T) and Bacillus horneckiae DSM 23495(T) with which it shared less than 98.0 % 16S rRNA gene sequence similarity. DNA-DNA relatedness values between strain WCC 4585(T) and five type strains of related species were ≤27 % and sequence similarity values based on groEL sequences were ≤88.7 %. On the basis of the characteristics presented, strain WCC 4585(T) is proposed to represent a novel species, Bacillus gottheilii sp. nov. The type strain is WCC 4585(T)( = DSM 23668(T) = CCUG 59876(T) = LMG 25856(T)).

Bacillus kochii sp. nov., isolated from foods and a pharmaceuticals manufacturing site

Three Gram-staining-positive, strictly aerobic, motile, catalase-positive, endospore-forming rods, designated WCC 4582T, WCC 4581 and WCC 4583, were isolated from two different food sources and a pharmaceuticals production site. The three isolates were highly similar in their 16S rRNA gene sequences (100 % similarity) and groEL sequences (99.2–100 % similarity), Fourier-transform infrared spectroscopic fingerprints and other features tested. The isolates were most closely related to Bacillus horneckiae ; the isolates and the type strain of B. horneckiae shared 97.6 % and 89.6 % 16S rRNA gene and groEL sequence similarities, respectively. The organisms grew optimally at 30 °C, at pH 7 and in the presence of 0.5 % (w/v) NaCl. The cell-wall peptidoglycan of WCC 4582T contained meso-diaminopimelic acid (A1γ) and the genomic DNA G+C content was 36.4 mol%. DNA–DNA relatedness between strain WCC 4582T and B. horneckiae NRRL B-59162T was 17 %. The three isolates are considered to represent a novel species of the genus Bacillus , for which the name Bacillus kochii sp. nov. is proposed. The type strain is WCC 4582T ( = DSM 23667T = CCUG 59877T = LMG 25855T).

Microbial biodiversity, quality and shelf life of microfiltered and pasteurized extended shelf life (ESL) milk from Germany, Austria and Switzerland

Information on factors limiting the shelf life of extended shelf life (ESL) milk produced by microfiltration and subsequent pasteurization is very limited. In this study, three different batches of ESL milk were analyzed at different stages of the production process and during storage at 4 °C, 8 °C and 10 °C in order to evaluate the changes in bacterial cell counts, microbial diversity and enzymatic quality. Additionally, detailed biodiversity analyses of 250 retail ESL milk packages produced by five manufacturers in Germany, Austria and Switzerland were performed at the end of shelf life. It was observed that microfiltration decreased the microbial loads by 5-6 log₁₀ units to lower than 1 CFU/mL. However, bacterial counts at the end of shelf life were extremely variable and ranged between <1 and 8 log₁₀ CFU/mL. 8% of all samples showed spoilage indicated by cell counts higher than 6 log₁₀ CFU/mL. The main spoilage groups of bacteria were Gram-negative post-process recontaminants (Acinetobacter, Chryseobacterium, Psychrobacter, Sphingomonas) and the spore formers Paenibacillus and Bacillus cereus, while other spore formers and Microbacterium spp. did not reach spoilage levels. Paenibacillus spp. and B. cereus apparently influenced enzymatic spoilage, as indicated by increased free fatty acid production, pH 4.6 soluble peptide fractions and off-flavors. In some cases, enzymatic spoilage was observed although microbial counts were well below 6 log₁₀ CFU/mL. Thirteen B. cereus isolates were characterized for their toxin profiles and psychrotolerance. Hbl, nhe, and cytK toxin genes were detected in ten, thirteen, and four isolates, respectively, whereas the ces gene was always absent. Interestingly, only three of the thirteen isolates could be allocated to psychrotolerant genotypes, as indicated by the major cold shock cspA gene signature. Generally, large discrepancies in microbial loads and biodiversity were observed at the end of shelf life, even among packages of the same production batch. We suggest that such unexpected differences may be due to very low cell counts after ESL treatment, causing stochastic variations of initial species distributions in individual packages. This would result in the development of significantly different bacterial populations during cold storage, including the occasional development of high numbers of pathogenic species such as B. cereus or Acinetobacter.

Surface microbial consortia from Livarot, a French smear-ripened cheese

The surface microflora (902 isolates) of Livarot cheeses from three dairies was investigated during ripening. Yeasts were mainly identified by Fourier transform infrared spectroscopy. Geotrichum candidum was the dominating yeast among 10 species. Bacteria were identified using Biotype 100 strips, dereplicated by repetitive extragenic palindromic PCR (rep-PCR); 156 representative strains were identified by either BOX-PCR or (GTG)(5)-PCR, and when appropriate by 16S rDNA sequencing and SDS-PAGE analysis. Gram-positive bacteria accounted for 65% of the isolates and were mainly assigned to the genera Arthrobacter , Brevibacterium , Corynebacterium , and Staphylococcus . New taxa related to the genera Agrococcus and Leucobacter were found. Yeast and Gram-positive bacteria strains deliberately added as smearing agents were sometimes undetected during ripening. Thirty-two percent of the isolates were Gram-negative bacteria, which showed a high level of diversity and mainly included members of the genera Alcaligenes , Hafnia , Proteus , Pseudomonas , and Psychrobacter . Whatever the milk used (pasteurized or unpasteurized), similar levels of biodiversity were observed in the three dairies, all of which had efficient cleaning procedures and good manufacturing practices. It appears that some of the Gram-negative bacteria identified should now be regarded as potentially useful in some cheese technologies. The assessment of their positive versus negative role should be objectively examined.

Species and strain identification of lactic acid bacteria using FTIR spectroscopy and artificial neural networks

Lactic acid bacteria (LAB) are a heterogeneous group of micro-organisms with high relevance for fermented food and beverages as well as human and animal health. Identification of LAB is complicated by species richness, a high degree of heterogeneity between species and the presence of very closely related species at the same time. In the present study we developed identification systems based on FTIR spectra and artificial neural networks (ANNs) for species identification of 92 LAB species out of nine genera and strain identification of probiotic and environmental Enterococcus faecium strains used as additives for animal feed. The reference databases established in this work permit reliable identification of LAB with accuracies of 93.2% at species and 97.1% at strain level for Ec. faecium, demonstrating the excellent suitability of FTIR spectroscopy as a technique applicable for simultaneous species and strain identification.