The world of silage inoculants has long featured Lactobacillus plantarum as the poster child for lactic acid fermentation. For decades, many assumed it was purely “homofermentative,” meaning it would convert sugars exclusively into lactic acid—a strong acid that quickly lowers pH. In practice, however, L. plantarum is facultatively heterofermentative: it can produce different end products if conditions change (like when pentoses or other non-hexose substrates become predominant).
In older or lower-sugar forages, its aggressive acid production was enough to safeguard silage from spoilage. But modern grass systems—often high in residual sugars, heavily buffered by protein and minerals, and prone to weather extremes—test the limits of any single-strain approach. Farmers and consultants today must appreciate that the so-called “homofermentative” L. plantarum is not always the panacea it was once hailed to be.
Misapprehension of L. plantarum as Homofermentative
The confusion arises because L. plantarum typically follows a homofermentative pathway when fermenting hexoses (glucose, fructose). That is where the notion of “little to no dry matter (DM) loss” once took root. But many silages, especially highly fertilised grass or multi-cut systems, do not present a simple diet of hexose sugars.
Worse yet, in modern high-sugar forages, an overabundance of lactic acid can become a spoilage risk at feed-out. If oxygen seeps in (due to suboptimal sealing or during daily feed-out), lactate-assimilating yeasts quickly thrive on that lactic acid “fuel,” driving up silage temperature and triggering the dreaded cascade of aerobic spoilage. In other words, a big lactic acid “win” during the anaerobic phase can become the Achilles’ heel once air is introduced.
Unsuitability in Modern Circumstances
Over time, it’s become clear that single-strain L. plantarum inoculants—especially if promoted as “purely homofermentative”—may falter under present-day conditions. Modern ryegrass and other forage species, bred for higher sugar and higher digestibility, present a fermentation scenario quite unlike the older, lower-sugar crops from decades past. Add to that frequent or late slurry applications, unpredictable weather windows, and the need to cut younger grasses for peak nutritional value, and the silo environment is more variable—and often more buffered—than ever.
Where L. plantarum was once automatically lauded for “fast pH drop,” we now see that it can stumble if buffering impedes that pH decline or if oxygen infiltration allows competing microbes to flourish early. It may produce large volumes of lactic acid, but the silage can become susceptible to intense yeast activity at feed-out. In essence, modern circumstances expose the shortfalls of older “one-strain-fits-all” inoculants.
The Rise of L. buchneri and Oxygen Scavenging Silage Inoculants
Enter next-generation silage inoculants featuring heterofermentative strains such as Lactiplantibacillus buchneri. Rather than a sole focus on lactic acid, L. buchneri produces moderate amounts of acetic acid, which strongly inhibits yeast and mould growth. Under older formulations, however, there was a catch: traditional L. buchneri strains often took four to six weeks to generate sufficient acetic acid, meaning they didn’t address the early or mid-silage risks.
Improved L. buchneri strains are now available with more immediate activity or balanced acetic acid production. Even more promising is pairing L. buchneri strain LB1819 with an oxygen-scavenging Lactococcus lactis—for example, L. lactis O224. By consuming residual oxygen and producing lactic acid early, L. lactis O224 can create an environment in which the L. buchneri (and any other co-inoculated LAB) outcompete spoilage microbes from day one, instead of waiting weeks. The result is a silage that is less prone to hidden heating or DM losses during storage, while still reaping the long-term benefits of an acetic-acid-based defence against yeasts when you open the clamp.
SiloSolve® FC is the only silage inoculant with a patented combination of L. buchneri LB1819 and L. lactis O224.
Developed by Novonesis (formerly Chr. Hansen), a global biotech leader, it’s backed by €4.5 million in research, peer-reviewed studies, and real-world trials.
Benefits of a Balanced Approach
When homofermentative and heterofermentative strains are intelligently combined, farmers can achieve:
– Rapid early pH drop (preserving proteins, curtailing clostridia)
– Moderate levels of acetic acid for robust aerobic stability at feed-out
– Lower ethanol production compared to L. plantarum gone rogue under suboptimal conditions (high ethanol in L.plantarum silages is also a product of yeast growth and fermentation already during ensiling).
– Less risk of runaway lactic acid fuelling lactate-assimilating yeasts
It’s this synergy—rather than any single-strain magic—that truly meets the demands of modern, high-quality forage ensiling.
Clostridia and “Strains Matter” L. lactis SR3.54
While lactic and acetic acid strategies are central to controlling spoilage yeasts and moulds, another spectre looms large in wet or high-protein forages: clostridia. These bacteria can devastate silage by producing butyric acid, degrading protein into ammonia, and creating toxic end products. Some older L. plantarum strains performed well against clostridia if enough hexose sugars were present to drive the pH down swiftly, but that’s not a given in all high-risk forages.
This is where specialised Lactococcus lactis strains like SR3.54 (patented in SiloSolve® MC) come to the fore. Meticulously researched for their anti-clostridial properties, they combine fast growth with targeted bacteriocin production, effectively knocking back clostridia before they can gain a foothold. Trial data shows that L. lactis SR3.54 can rival (and sometimes exceed) chemical agents in controlling clostridia, all while avoiding some of the handling and safety concerns posed by acids or salt-based preservatives. It is the quintessential example that not all “LAB” are alike, and that “strain” can be more significant than the broad species label.
Conclusion: Embracing Tailored Silage Inoculants for Today’s Crops
The silage industry has evolved beyond simplistic messaging about L. plantarum being a “homofermentative panacea.” In reality, L. plantarum is facultatively heterofermentative and can present real downsides—particularly in modern high-sugar, high-buffering conditions where lactic acid overproduction can breed aerobic instability. On the other hand, select L. buchneri strains, especially when paired with oxygen-scavenging Lactococcus lactis like O224, can deliver a safer, more stable fermentation that resists yeast spoilage. For high-clostridia-risk forages, L. lactis SR3.54 exemplifies a specialised strain that squares off against these formidable spoilage organisms.
Ultimately, “strains matter” is far more than a catchphrase; it is a fundamental principle in modern silage inoculant design. By recognising each strain’s specific metabolic pathways, growth patterns, and antagonisms against pathogens, farmers can build inoculant programs that proactively address the real challenges of current-day forage production. That’s a far cry from hoping “old technology” might still suffice. Instead, it signals a future where scientifically validated, targeted inoculants preserve more DM, capture more nutrients, and yield safer, more stable silages—regardless of the myriad stressors nature and our agronomic intensification throw their way.
