Paenibacillus

Paenibacillus is a genus of

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  A colony generated by the chiral morphotype bacteria of P. dendritiformis: The colony diameter is 5 cm and the colors indicate the bacterial density (bright yellow for high density). The branches are curly with well-defined handedness.
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  A colony generated by P. vortex sp. bacteria: The colony diameter is 5 cm and the colors indicate the bacterial density (bright yellow for high density). The bright dots are the vortices described in the text.
• 
  A colony generated by the branching (tip splitting) morphotype bacteria of P. dendritiformis: The colony diameter is 6 cm and the colors indicate the bacterial density (darker shade for higher density).

Importance

Interest in Paenibacillus spp. has been rapidly growing since many were shown to be important^[23][24][25] for agriculture and horticulture (e.g. P. polymyxa), industrial (e.g. P. amylolyticus), and medical applications (e.g. P. peoriate). These bacteria produce various extracellular enzymes such as polysaccharide-degrading enzymes and proteases, which can catalyze a wide variety of synthetic reactions in fields ranging from cosmetics to biofuel production. Various Paenibacillus spp. also produce antimicrobial substances that affect a wide spectrum of micro-organisms^[26][27][28] such as fungi, soil bacteria, plant pathogenic bacteria, and even important anaerobic pathogens such as Clostridium botulinum.

More specifically, several Paenibacillus species serve as efficient

Candidatus Paenibacillus glabratella causes white nodules and high mortality of Biomphalaria glabrata freshwater snails.^[33] This is potentially important because Biomphalaria glabrata is an intermediate host of schistosomiasis.^[33]

A major challenge in the dairy industry is reducing premature spoilage of fluid milk caused by microbes.^[34] Paenibacillus is often isolated from both raw and pasteurized fluid milk. The most predominant Paenibacillus species isolated is Paenibacillus odorifer. Species in the Paenibacillus genus can sporulate to survive the pasteurization of milk and are subsequently able to germinate in refrigerated milk, despite the low temperatures. Many bacterial genera have a cold shock response, which involves the production of cold shock proteins that help the cell facilitate global translation recovery.^[34] Little is currently known about the cold shock response in Paenibacillus compared to other species, but it has been shown that Paenibacillus species contain many genetic elements associated with the cold shock response.^[35] Paenibacillus odorifer was demonstrated to carry multiple copies of these cold shock associated genetics elements.^[34]

Pattern formation, self-organization, and social behaviors

Several Paenibacillus species can form complex patterns on semisolid surfaces. Development of such complex colonies require self-organization and cooperative behavior of individual cells while employing sophisticated chemical communication called quorum sensing.^{[13][14][18][20][21][36][37][38]} Pattern formation and self-organization in microbial systems is an intriguing phenomenon and reflects social behaviors of bacteria^[37][39] that might provide insights into the evolutionary development of the collective action of cells in higher organisms.^{[13][37][40][41][42][43][44]}

Pattern forming in P. vortex

One of the most fascinating pattern forming Paenibacillus species is P. vortex, self-lubricating,

An additional intriguing pattern forming Paenibacillus species is P. dendritiformis, which generates two different morphotypes[13]^{[14][18][19][20][21]} – the branching (or tip-splitting) morphotype and the chiral morphotype that is marked by curly branches with well-defined handedness (see pictures).

These two pattern-forming Paenibacillus strains exhibit many distinct physiological and genetic traits, including