Microbial Diversity Profiling of Polysaccharide (gum)-Producing Bacteria Isolated from a South African Sugarcane Processing Factory

Microbiome Analysis of Sugarcane Juices and Biofilms from Louisiana Raw Sugar Factories

“…However, Lactobacillales do not appear as an abundant taxon in amplicon-sequencing results of the sugarcane rhizosphere ( 19 – 21 ), which suggests that they may become enriched during the delay between harvesting and milling. Our finding that Weissella or Lactobacillus were more abundant than Leuconostoc in certain samples, such as MJ-Fact1-Oct and Biofilm1-Fact3-Dec support recent commentary that these bacteria may play a larger role in EPS production than previously thought ( 12 ). A survey of the fungi present using the ITS1 marker region showed a large diversity of taxa in juices, but notably revealed that biofilms are predominantly Saccharomyces .…”

“…Lactobacillales , which are the most abundant bacteria in isolation-based studies ( 11 – 14 ), were similarly the most abundant in the 16S V4 data set in this study. However, Lactobacillales do not appear as an abundant taxon in amplicon-sequencing results of the sugarcane rhizosphere ( 19 – 21 ), which suggests that they may become enriched during the delay between harvesting and milling.…”

“…The amplicon sequencing data revealed many taxa that were previously unreported from sugarcane factories. To explore whether these other taxa are likely to produce dextrans or levans like other previously reported bacteria, BLAST searches were used to query genomes deposited in the NCBI RefSeq database for the 12 most abundant bacterial genera and any other genera found in recent culture-based studies ( 11 – 14 ) ( Fig. 3 ).…”

“…As a culture-independent method, amplicon-based sequencing was able to reveal a much greater diversity of bacteria present in raw sugar factories in comparison to isolation-based studies carried out from raw sugar factory samples, including an isolation study that was carried out with some of the same samples that were extracted for amplicon-based sequencing ( 11 – 14 ) ( Table 1 ). One limitation of amplicon-based sequencing is the inability to reveal phenotypic differences arising from species- or strain-level diversity.…”

“…Historically, sucrose degradation and dextran formation in factories has been mostly attributed to the lactic acid bacterium species Leuconostoc mesenteroides ( 9 , 10 ). However, recent studies have isolated diverse bacteria from sugarcane factories that can also produce EPS from sucrose in addition to Leuconostoc , such as Bacillus , Gluconobacter , Lactobacillus , Streptococcus , and Weissella ( 11 – 14 ). These results suggest that raw sugar factories may be exposed to diverse microbes, which also contribute to sugarcane juice deterioration.…”