据最近一篇发表于Proceedings of the National Academy of Sciences杂志的研究报告，科学家在研究枯草芽孢杆菌(Bacillus subtilis)时发现，细菌在受胁迫的环境中，整个细菌群落能够通过权衡，从而采取不同的策略生存下去。
据作者介绍，细菌在胁迫环境下，能够通过开启和关闭的某些基因来维持生存的方式，不仅可以揭示生物系统间相互作用的复杂性，还有助于经济学家以及政治科学家建立类似的数学模型来描述人类做决策的复杂过程。
自然界中，细菌一般是群居生活的，一个小小的细菌群落中细菌的总数就有可能超过地球上所有人口的100倍。许多细菌对多种极端环境（如饥饿，毒性和放射性）的应答往往是形成孢子，当环境得到改善后，孢子可以通过出芽形成正常的细菌。枯草芽孢杆菌可在10小时内完成该过程，整个过程大约需要500个基因的参与。
细菌在形成孢子的过程中，其最终产物并不一定全都是孢子，在某些情况下可以进入到另一种被称之为“competence”的状态中。在这种状态，细菌只是细胞膜发生改变，使其能够轻易地从死亡的母细胞中吸收营养物质，像这样，细菌即使遇到不良环境中，也可不通过形成孢子的形式安然度过危险期。这种状态的优势在于，当环境好转，细菌能够后迅速恢复到正常功能，但这种状态的劣势在于，一旦环境变得更恶劣，那么细菌将面临更大的死亡危险。
因此，细菌在面临不利环境时，究竟要以哪种状态生存的选择类似于一个著名的博弈论问题——囚徒困境(Prisoner's Dilemma)。而且对整个细菌群落来说，这种博弈显得更为复杂。每一个细菌必须做出决策——要么形成孢子，要么进入“competence”状态。研究人员发现，当细菌遭遇不利的周围环境时，会及时发出化学信号通知其它细菌，以让其做好相应的准备。（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS December 7, 2009, doi: 10.1073/pnas.0912185106
Deciding fate in adverse times: Sporulation and competence in Bacillus subtilis
Daniel Schultza, Peter G. Wolynesa,1, Eshel Ben Jacoba,b,1,2 and José N. Onuchica,1,2
aCenter for Theoretical Biological Physics, University of California at San Diego, La Jolla, CA 92093-0374; and
bSchool of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv, Israel
Bacteria serve as the central arena for understanding how gene networks and proteins process information and control cellular behaviors. Recently, much effort has been devoted to the investigation of specific bacteria gene circuits as functioning modules. The next challenge is the integrative modeling of complex cellular networks composed of many such modules. A tractable integrative model of the sophisticated decision-making signal transduction system that determines the fate between sporulation and competence is presented. This model provides an understanding of how information is sensed and processed to reach an “informative” decision in the context of cell state and signals from other cells. The competence module (ComK dynamics) is modeled as a stochastic switch whose transition rate is controlled by a quorum-sensing unit. The sporulation module (Spo0A dynamics) is modeled as a timer whose clock rate is adjusted by a stress-sensing unit. The interplay between these modules is mediated via the Rap assessment system, which gates the sensing units, and the AbrB–Rok decision module, which creates an opportunity for competence within a specific window of the sporulation timer. The timer is regulated via a special repressilator-like inhibition of Spo0A* by Spo0E, which is itself inhibited by AbrB. For some stress and input signals, this repressilator can generate a frustration state with large variations (fluctuations or oscillations) in Spo0A* and AbrB concentrations, which might serve an important role in generating cell variability. This integrative framework is a starting point that can be extended to include transition into cannibalism and the role of colony organization.
