Vanessa Pittet

Complete Genome Sequence of the Beer Spoilage Organism Pediococcus claussenii ATCC BAA-344T

Pediococcus claussenii is a common brewery contaminant. We have sequenced the chromosome and plasmids of the type strain P. claussenii ATCC BAA-344. A ropy variant was chosen for sequencing to obtain genetic information related to growth in beer, as well as exopolysaccharide and possibly biofilm formation by this organism.

Transcriptome Sequence and Plasmid Copy Number Analysis of the Brewery Isolate Pediococcus claussenii ATCC BAA-344T during Growth in Beer

Growth of specific lactic acid bacteria in beer leads to spoiled product and economic loss for the brewing industry. Microbial growth is typically inhibited by the combined stresses found in beer (e.g., ethanol, hops, low pH, minimal nutrients); however, certain bacteria have adapted to grow in this harsh environment. Considering little is known about the mechanisms used by bacteria to grow in and spoil beer, transcriptome sequencing was performed on a variant of the beer-spoilage organism Pediococcus claussenii ATCC BAA-344T (Pc344-358). Illumina sequencing was used to compare the transcript levels in Pc344-358 growing mid-exponentially in beer to those in nutrient-rich MRS broth. Various operons demonstrated high gene expression in beer, several of which are involved in nutrient acquisition and overcoming the inhibitory effects of hop compounds. As well, genes functioning in cell membrane modification and biosynthesis demonstrated significantly higher transcript levels in Pc344-358 growing in beer. Three plasmids had the majority of their genes showing increased transcript levels in beer, whereas the two cryptic plasmids showed slightly decreased gene expression. Follow-up analysis of plasmid copy number in both growth environments revealed similar trends, where more copies of the three non-cryptic plasmids were found in Pc344-358 growing in beer. Transcriptome sequencing also enabled the addition of several genes to the P . claussenii ATCC BAA-344T genome annotation, some of which are putatively transcribed as non-coding RNAs. The sequencing results not only provide the first transcriptome description of a beer-spoilage organism while growing in beer, but they also highlight several targets for future exploration, including genes that may have a role in the general stress response of lactic acid bacteria.

RT-qPCR analysis of putative beer-spoilage gene expression during growth of Lactobacillus brevis BSO 464 and Pediococcus claussenii ATCC BAA-344 T in beer

Lactic acid bacteria (LAB) contamination of beer presents a continual economic threat to brewers. Interestingly, only certain isolates of LAB can grow in the hostile beer environment (e.g., as studied here, Lactobacillus brevis BSO 464 (Lb464) and a non-ropy isolate of Pediococcus claussenii ATCC BAA-344T (Pc344NR)), indicating that significant genetic specialization is required. The genes hitA, horA, horB, horC, and bsrA, which have been proposed to confer beer-spoiling ability to an organism, are suspected of counteracting the antimicrobial effects of hops. However, these genes are not present in the same combination (if at all) across beer-spoiling organisms. As such, we sought to investigate the extent to which these genes participate during Lb464 and Pc344NR mid-logarithmic growth in beer through reverse transcription quantitative PCR analysis. We first determined the optimal reference gene set needed for data normalization and, for each bacterium, established that two genes were needed for accurate assessment of gene expression. Following this, we found that horA expression was induced for Pc344NR, but not for Lb464, during growth in beer. Instead, horC expression was dramatically increased in Lb464 when growing in beer, whereas no change was detected for the other putative beer-spoilage-related genes. This indicates that HorC may be one of the principle mediators enabling growth of Lb464 in beer, whereas in Pc344NR, this may be attributable to HorA. These findings not only reveal that Lb464 and Pc344NR are unique in their beer-specific genetic expression profile but also indicate that a range of genetic specialization exists among beer-spoilage bacteria.

Role of plasmids in Lactobacillus brevis BSO 464 hop tolerance and beer spoilage

ABSTRACT Specific isolates of lactic acid bacteria (LAB) can grow in the harsh beer environment, thus posing a threat to brew quality and the economic success of breweries worldwide. Plasmid-localized genes, such as horA, horC, and hitA, have been suggested to confer hop tolerance, a trait required for LAB survival in beer. The presence and expression of these genes among LAB, however, do not universally correlate with the ability to grow in beer. Genome sequencing of the virulent beer spoilage organism Lactobacillus brevis BSO 464 revealed the presence of eight plasmids, with plasmids 1, 2, and 3 containing horA, horC, and hitA, respectively. To investigate the roles that these and the other five plasmids play in L. brevis BSO 464 growth in beer, plasmid curing with novobiocin was used to derive 10 plasmid variants. Multiplex PCRs were utilized to determine the presence or absence of each plasmid, and how plasmid loss affected hop tolerance and growth in degassed (noncarbonated) beer was assessed. Loss of three of the eight plasmids was found to affect hop tolerance and growth in beer. Loss of plasmid 2 (horC and 28 other genes) had the most dramatic effect, with loss of plasmid 4 (120 genes) and plasmid 8 (47 genes) having significant, but smaller, impacts. These results support the contention that genes on mobile genetic elements are essential for bacterial growth in beer and that beer spoilage ability is not dependent solely on the three previously described hop tolerance genes or on the chromosome of a beer spoilage LAB isolate.

Genome Sequence of Lactobacillus rhamnosus ATCC 8530

Lactobacillus rhamnosus is found in the human gastrointestinal tract and is important for probiotics. We became interested in L. rhamnosus isolate ATCC 8530 in relation to beer spoilage and hops resistance. We report here the genome sequence of this isolate, along with a brief comparison to other available L. rhamnosus genome sequences.

Reclassification of Paralactobacillus selangorensis Leisner et al. 2000 as Lactobacillus selangorensis comb. nov.

The taxonomic status of Paralactobacillus selangorensis is described and, based on evidence presented, transfer of the species to the genus Lactobacillus with the name Lactobacillus selangorensis comb. nov. is proposed. This reclassification is supported by multilocus sequence analysis of the 16S rRNA gene and portions of the cpn60, pheS and rpoA genes. Mode of cell division and existing phenotypic information also show that P. selangorensis cannot be differentiated from the genus Lactobacillus. The type strain of Lactobacillus selangorensis comb. nov. is ATCC BAA-66(T) (=LMG 17710(T) =CIP 106482(T)).

Key Aspects for Successful Design and Implementation of Passive Water Treatment Systems

Introduction Water treatment has been implemented for decades to treat water supplies as well as “wastewater” from a variety of sources. Noteworthy are successes treating challenging contaminated waters, including industrial sources, mining influenced waters, and oil and gas produced waters. Passive water treatment is a process of simultaneously or sequentially mitigating contaminants and/or acidity and physicochemical properties in a man-made system. This is achieved by capitalizing on biological, geochemical, and coupled biogeochemical reactions, followed by the physical removal and sequestration of constituents. In its truest form, a passive water treatment system (PWTS) does not require power or chemicals after construction and can be designed as a sustainable system lasting for decades or longer with minimal intervention or maintenance. For waters that contain constituents of concern that are not amenable to treatment by naturally occurring biological, physical, or chemical pathways (e.g. sodium, chl...

Genome Sequence of Rapid Beer-Spoiling Isolate Lactobacillus brevis BSO 464

ABSTRACT The genome of brewery-isolate Lactobacillus brevis BSO 464 was sequenced and assembly produced a chromosome and eight plasmids. This bacterium tolerates dissolved CO2/pressure and can rapidly spoil packaged beer. This genome is useful for analyzing the genetics associated with beer spoilage by lactic acid bacteria.